bluuebunny/crossref_metadata_2025 huggingface dataset:
BIOCHEMISTRY OF BROWN FAT AND LIVER OF HIBERNATING GOLDEN-MANTLED GROUND SQUIRRELS (CITELLUS LATERALIS)
Authors: Chaffee R. R. J. , Pengelley E. T. , Allen J. R. , Smith R. E.
Published: April 2011

Studies were made on the effects of cold acclimation culminating in hibernation on the weight and mitochondrial nitrogen content and enzymatic activity of brown fat and liver of ground squirrels (Citellus lateralis). The hibernating animals were living at a room temperature of 2 ± 1 °C, the controls at 24 ± 2 °C. The body and liver weights of the hibernating animals were both 20% lower than those of the controls, but the brown fat of the hibernators was 40% greater in absolute weight and its ratio to body weight was double that of the controls. Respiration rates of liver and interscapular brown fat mitochondria from both control and hibernating squirrels were determined with various substrates. Oxidation of α-glycerophosphate and glutamate by brown fat mitochondria from hibernating animals was 47% and 36% higher, respectively, than control values. Liver mitochondria from hibernating animals were 50% higher in oxidation of succinate than were control mitochondria, but 34% lower in oxidation of α-glycerophosphate. The increased oxidative activity of brown fat, together with the increased ratio of brown fat weight to body weight, indicates that the thermogenic capability of brown fat is enhanced in the process of preparation for hibernation.
PROPERTIES AND CLASSIFICATION OF THE SOLUBLE ESTERASES OF HUMAN BRAIN
Authors: Ecobichon D. J.
Published: April 2011

Water-soluble proteins and enzymes of human brain were separated by vertical zone electrophoresis in starch gel. Fifteen bands of esterase activity were detected in brain. Various substrates and inhibitors were used in efforts to identify enzymes in addition to a comparison of the esterase pattern with patterns obtained from other human tissues. One zone, composed of four bands of acetylesterase activity, was found to be common to all the tissues investigated with the exception of serum. Two bands of cholinesterase and two bands of A-esterase activity were identified. The remaining bands, which were aliesterases possessing broad overlapping substrate specificity and inhibitor sensitivity, were electrophoretically different from those of other tissues. Observations on alkaline phosphatase, acid phosphatase, and lactate dehydrogenase were recorded for comparison with the data on esterases.
PHARMACOLOGICAL REACTIVITY OF DYSTROPHIC MUSCLE
Authors: Beaulnes A. , Bois P. , Carle R.
Published: April 2011

The effects of curarizing drugs, anticholinesterases, and musculotropic substances were studied on the phrenic nerve – diaphragm preparation of the hereditarily dystrophic mouse and of the rat treated with N,N-dimethyl-p-phenylenediamine (PPD), a cytotoxic substance producing dystrophic-like lesions. Both species showed an increased resistance to the neuromuscular blocking activity of d-tubocurarine. Gallamine was also less potent in the dystrophic mouse than in its normal littermate. Both species showed an increased sensitivity to the initial stimulant effect of succinylcholine; on the other hand, the depressant effect of succinylcholine was less intense in PPD-treated rats but unaltered in the dystrophic mouse. The response to neostigmine and physostigmine was decreased in the PPD-treated rat but enhanced in the dystrophic mouse. Musculotropic drugs (chlorpromazine, tetrodotoxin, xanthine derivatives, and veratrine) produced similar effects in normal and dystrophic mice. Two hypotheses are suggested to explain these changes in sensitivity in the dystrophic mouse diaphragm: (a) an increased production of an acetylcholine-like material, and (b) an increase in the number of acetylcholine-sensitive sites on the cell membrane. The changes in drug reactivity of the PPD-treated rat are considered to be due to a functional denervation caused by the cytotoxic properties of PPD.
COMBINED EFFECTS OF ALDOSTERONE, VASOPRESSIN, AND CORTICOSTERONE ON SALT AND WATER DISTRIBUTION IN THE NEUROHYPOPHYSECTOMIZED ADRENALECTOMIZED RAT
Authors: Friedman Sydney M. , Gustafson Brigid , Hamilton Dorothy
Published: April 2011

The interaction of aldosterone, vasopressin, and corticosterone on salt and water distribution was examined in the neurohypophysectomized adrenalctomized rat by use of conventional partition methods. When aldosterone and vasopressin are given in combination, they act in opposition and sodium is gained or lost depending on which is dominant. Similarly, the desalting effect of corticosterone can blunt or even reverse the sodium-accumulating effect of aldosterone. When all three hormones are given together the salt-losing effects of vasopressin and corticosterone are not additive. Instead, the administration of a modest amount of vasopressin in the presence of aldosterone and corticosterone results in a combination which favors, in the muscle, significant sodium accumulation and potassium loss. These findings indicate that the result obtained on administration of any one of these three hormones to the intact animal depends on the homeostatically adjusted levels of the other two.
DEOXYRIBONUCLEIC ACID LABELLING AFTER TRITIATED THYMIDINE INJECTION
Authors: Brière N. , Isler H.
Published: April 2011

Young rats were injected with thymidine-3H and the level of radioactivity in their blood was measured by a highly sensitive radioautographic technique. Radioactivity (10−6 μcurie/ml) was still detected in serum 7 days after injection. To determine whether the blood of these rats contained deoxyribonucleic acid (DNA) precursors, the sera, taken at various time intervals after injection, were introduced into tissue culture chambers. By radioautography of these cultures, it was found that they contained cells with labelled nuclei, even when exposed to sera taken 30 hours after injection. The presence of nuclear precursors in these sera probably indicates a reutilization of DNA from other cells.
PROPRANOLOL (INDERAL) IN EXPERIMENTALLY-INDUCED CARDIAC ARRHYTHMIAS
Authors: Lucchesi B. R. , Whitsitt L. S. , Brown N. L.
Published: April 2011

Propranolol (Inderal), a new, potent, non-carcinogenic beta adrenergic receptor antagonist has been shown to possess antiarrhythmic activity when tested against experimentally induced cardiac arrhythmias. The potent beta adrenergic receptor inhibition produced by propranolol leads to a prevention of those cardiac arrhythmias resulting from a combination of a sensitizing agent and a sympathomimetic amine. Methylchloroform–adrenaline and U-0882–isoproterenol arrhythmias were prevented by previous administration of propranolol at a dose sufficient to produce beta adrenergic receptor blockade.Propranolol has been shown to be capable of reversing ventricular tachycardia associated with ouabain intoxication in the anesthetized dog. The agent exerts an effect upon the ouabain-induced ventricular automatic focus and abolishes the activity of the abnormal pacemaker. The mechanism, although unknown, is not believed to be associated with the ability of propranolol to produce beta adrenergic receptor blockade.
IDENTIFICATION OF ACETYLCHOLINE, HISTAMINE, AND 5-HYDROXYTRYPTAMINE IN GIRARDINIA HETEROPHYLLA (DECNE.)
Authors: Saxena Pramod R. , Tangri K. K. , Bhargava K. P.
Published: April 2011

The stinging nettle Girardinia heterophylla (Decne.) was investigated for the presence of pharmacologically active substances which could account for the typical inflammatory reaction this plant is known to produce. The extracts of the plant were tested on the biological test objects and later subjected to chromatography. The acetone-extracted material of the plant showed the presence of acetylcholine and 5-hydroxytryptamine, and histamine was found in the acid-treated extract. The occurrence of a histamine liberator was not indicated.
WATER INTAKE OF RATS IMMEDIATELY AFTER EXPOSURE TO A COLD ENVIRONMENT
Authors: Fregly Melvin J. , Waters Irving W.
Published: April 2011

Rats exposed to air at 6 °C for 1, 3, 6, 10, and 12 days manifested an apparent "thirst" upon return to a warm (26 °C) environment. Drinking began within 80 minutes and continued for at least 24 hours after removal from the cold. Up to 10% of the 24-hour fluid intake was ingested within one-half hour after removal from the cold. During exposure to cold for 1 to 3 days, water intake either remained unchanged or decreased compared with values obtained before cold exposure, while food intake increased within 24 hours. The relationship between simultaneous daily intake of food and water was altered significantly by cold such that less water was ingested for a given food intake during exposure to cold than before exposure. A state of dehydration relative to controls may be present in cold-exposed rats as suggested by their decreased water intake for a given food intake and by increases in both osmolality and chloride concentration of serum. The increased water intake immediately after removal from the cold may be a manifestation of the relative dehydration. However, persistence of an increased water intake up to 24 hours after removal from the cold is unexplained.
THE CONTRACTILE RESPONSE OF THE UTERUS TO COCAINE
Authors: Daniel E. E. , Wolowyk M.
Published: April 2011

Cocaine-induced contractures of rabbit uterine segments were analyzed. Similar responses were produced by other local anesthetics, but potency in producing contractures was unrelated to that in producing local anesthesia. Contractures were not produced by potentiation of endogenous catecholamines or by any mechanism related to stimulation of α-adrenergic receptors or oxytocin receptors. Receptors for serotonin and acetylcholine were also not involved. Depolarization of the uterine muscle cells prevented cocaine-induced contractures. They were calcium-dependent and disappeared more rapidly than responses to acetylcholine or noradrenaline in a calcium-free medium. They were restored both by strontium and by calcium, but more slowly than were acetylcholine responses. It is proposed that cocaine causes labilization of calcium loosely bound in the membrane in rabbit uterine segments and that this leads to contracture.
STUDIES ON ELECTRICALLY INDUCED THROMBOSIS AND RELATED PHENOMENA
Authors: Cowan C. R. , Monkhouse Frank C.
Published: April 2011

Microampere currents applied with metal electrodes to the mesenteric vessels of mice caused thrombosis, accompanied by electrolyte dissociation and gas formation. When the products of dissociation were removed, clumping, constriction, or thrombosis did not occur. When glass–starch electrodes were used, currents up to 200 μA, applied for 30 minutes, were without effect. Changing to platinum electrodes and applying 50-μA currents caused, in less than 30 seconds, constriction at the negative pole, clumping, and thrombosis, without constriction at the positive pole. Measurements showed an increase in pH at the negative pole and a decrease at the positive pole. When saline solutions with increased or decreased pH were applied to the vessels, constriction and thrombus formation occurred similar to those produced by electrical current. Experiments were done on heparinized blood in vitro with a U-tube designed to contain the products of electrolysis at each pole. With platinum electrodes a coagulum formed at the positive pole and pH changes occurred at both poles. With glass–starch electrodes these changes did not occur.
THE ACUTE RECTAL TOXICITY OF ACETYLSALICYLIC ACID
Authors: Coldwell Blake B. , Boyd Eldon M.
Published: April 2011

The LD50 ± S.E. of acetylsalicylic acid administered rectally to male albino rats was found to be 0.79 ± 0.027 g/kg, which is significantly less than the oral LD50. The minimal dose producing toxic symptoms was about 0.20 g/kg. The most significant toxic signs were ataxia, drowsiness, dyspnea, pallor, diarrhea, and anorexia. The immediate cause of death was respiratory failure preceded by coma or clonic convulsions. Loss in body weight, inhibition of food intake, and interval until death were dose-dependent. The drug caused diuresis and aciduria but no significant changes in colonic temperature, or in urinary glucose or protein. Death at 4 to 9 hours was associated with extensive capillary–venous congestion and at 24 hours and over with degenerative changes in the kidneys and liver. Congestive and hemorrhagic ulcers appeared in the pyloric stomach at 4 hours, reached a peak at 24 hours, and thereafter began to heal. Local reaction in the colon and cecum was limited to mild inflammation. Significant loss of weight and a gain in water level occurred in most organs.
OSTEOLYSIS IN THE FROG: THE EFFECTS OF PARATHORMONE
Authors: Bélanger L. F. , Drouin P.
Published: April 2011

Tadpoles of Rana catesbeiana treated intraperitoneally with doses of 18 to 54 units of mammalian parathyroid extract (Para-Thor-Mone, Lilly) underwent osteolysis as characterized by loss of mineral salt and organic matrix around mature osteocytes, metachromatic changes in the matrix, and production of protease. At the same time, the mature epiphyseal cartilage was lost in part, presumably through local proteolytic activity. The collagenase resorption of the tail was accelerated by 40% in 3 days.
FURTHER STUDIES OF THE PHARMACOLOGY OF THE PYLORIC REGION: ANALYSIS OF THE EFFECTS OF INTRA-ARTERIAL HISTAMINE, SEROTONIN, PHENYLDIGUANIDE, MORPHINE, AND OTHER DRUGS ON THE ANTRUM AND DUODENAL BULB
Authors: Daniel E. E.
Published: April 2011

The actions of drugs on the antrum and duodenum of the dog were analyzed by the use primarily of intra-arterial injections into the gastroepiploic artery while the electrical and contractile activity of these regions was recorded. Histamine (0.1 to 5 μg) usually caused excitation of second potentials (antrum) or fast spikes (duodenum), and contractions (both) and other effects similar to those produced by acetylcholine, though usually delayed in onset and more prolonged. Its effects were diminished or prevented by atropine, nicotine, and hexamethonium as well as by antihistaminics such as antazoline, cyproheptadine, and phenoxybenzamine. In the duodenum, histamine excitation was usually preceded by inhibition, and most antihistaminics also depressed responses to serotonin (5-HT), acetylcholine, or both. Low doses of serotonin (0.1 to 1 μg) most frequently caused excitation of the antrum and duodenum similar to that evoked by acetylcholine. This response was sometimes prolonged. These effects in the antrum were diminished or prevented by atropine, nicotine, methysergide, and bromolysergic acid (BOL), and less effectively antagonized by hexamethonium, morphine, and pronethalol. Phenoxybenzamine did not prevent excitation of the antrum by low doses of 5-HT, but tachyphylaxis following high doses of 5-HT (5 to 100 μg) or of phenyldiguanide (25 to 500 μg) did prevent such responses. Several of these agents also inhibited excitation of the duodenum induced by 5-HT and cross tachyphylaxis between 5-HT and phenyldiguanide was also observed. It was suggested that low doses of 5-HT, like phenyldiguanide, acted at a preganglionic site in the antrum and duodenum different from that at which histamine acts, presumably the non-medullated mucosal mechanoreceptors, and ultimately caused release of acetylcholine from postganglionic fibers. Phenyldiguanide in small doses (2 to 25 μg) acted like 5-HT to excite the antrum and duodenum. Analysis of its action with antagonists yielded results similar to those with 5-HT, and the occurrence of cross tachyphylaxis with 5-HT suggested a common site of action. Morphine (10 to 1000 μg) usually inhibited electrical and contractile activity in the antrum and stimulated these activities in the duodenum. The same results were obtained with intravenous injection (0.1 to 0.35 mg/kg). It. diminished responses to histamine, 5-HT, phenyldiguanide, and to a lesser extent, acetylcholine.
SEASONAL CHANGES IN THE PHYSIOLOGICAL RESPONSE OF MAN TO AN ACUTE COLD STRESS
Authors: Girling F.
Published: April 2011

Eight male human subjects, resting supine, and wearing swim trunks only, were exposed to an ambient temperature of 8.5 °C for 1 hour in the first week of each month from February 1964 to January 1965 inclusive. Skin, rectal, and air temperatures were measured with thermistor probes. Percentage oxygen in expired air and minute ventilation were measured, and heat production was calculated by Weir's method. Electrical activity from the muscles of all four limbs was measured to determine shivering response. Control values of resting respiration and heat production were obtained under comfortably warm conditions and showed marked seasonal variation, with minimum values in spring and maximum values in later summer. In the response to acute cold exposure, marked seasonal changes were found also which were superimposed on the seasonal changes in control values. The response to cold exposure indicated maximum acclimatization to cold in the spring and minimum in later summer. These results are discussed in terms of three modes of response to the cold stress: (i) insulative cooling, (ii) shivering thermogenesis, and (iii) nonshivering thermogenesis. The degree of acclimatization and temperature of exposure may determine the individual mode of response.
EFFECTS OF BREATHING GASES CONTAINING OXYGEN AND CARBON DIOXIDE AT 1 AND 3 ATMOSPHERES PRESSURE ON BLOOD FLOW AND OXYGENATION OF TUMORS
Authors: Kruuv Jack , Inch W. Rodger , McCredie John A.
Published: April 2011

Mice with established, immunologically compatible tumors were allowed to breathe air, O2, or 5% CO2 and 95% O2 at 1 and 3 atmospheres pressure. Tumor blood flow was determined by using the thermal circulation index, and oxygenation was measured polarographically. Pure oxygen at 1 atmosphere had no significant effect on blood flow within the tumor and in normal skin, but inhalation at 3 atmospheres decreased flow within both tissues. The addition of 5% CO2 to the oxygen increased flow at both pressures. Oxygenation was often improved in anoxic areas within the tumor on breathing 100% O2 at 1 atmosphere and in almost all animals at 3 atmospheres; the addition of 5% CO2 at either pressure usually further improved the oxygenation, but sometimes had the opposite effect at 3 atmospheres. The application of these results to the use of hyperbaric O2 in radiotherapy is discussed.
THE RELATIVE INFLUENCE OF NERVOUS CONTROL AND OF LOCAL WARMING ON ARTERIOLAR MUSCLE DURING INDIRECT VASODILATATION
Authors: Gaskell Peter , Hoeppner David L.
Published: April 2011

The relative importance of the inhibition of vasoconstrictor nerves and of concomitant local warming in the production of indirect vasodilatation was investigated in terms of the decrease in critical opening pressure (COP) of digital vessels during body heating. The COP of vessels in a finger of each hand was measured when both hands were kept at about 21 °C during body heating in control experiments and when one of the hands was allowed to warm in air in test experiments. In eight control experiments the COP's of vessels in both fingers fell together. In 25 test experiments they fell together in both fingers until the hand in air began to warm. The COP then fell more rapidly and farther in the finger which warmed. In the test experiments the difference between the reductions in COP in the two fingers was attributed to the effect of local warming. The total reduction in the hand which was prevented from warming was ascribed to inhibition of neurogenic smooth muscle tone. On the average, local warming reduced the COP by 1.3 mm Hg for each increase of 1 °C. Warming occurred when the COP was reduced to about 25 to 35 mm Hg. However, much higher values of COP can exist in the constricted subject. Therefore the initial smooth muscle constricting force may have to be greatly reduced by inhibition of vasoconstrictor nerves before appreciable warming occurs. Then local warming may play an important role in determining the degree of vasodilatation that occurs.
CERTAIN BLOOD CONSTITUENTS OF A LIZARD DURING HIBERNATION AND ACTIVITY
Authors: Zain-ul-Abedin M. , Katorski B.
Published: April 2011

Blood glucose, plasma nonesterified fatty acids (NEFA), plasma esterified fatty acids (EFA), plasma protein, and blood nonprotein nitrogen (NPN) were measured in a lizard, Uromastix hardwickii, both during activity and hibernation. In hibernating lizards the blood glucose and plasma protein levels were unaltered, plasma NEFA and EFA almost doubled, and the NPN of the protein-free filtrate prepared with trichloroacetic acid was decreased by 15%, whereas that determined on the zinc sulfate – sodium hydroxide filtrate was unaltered. These findings are discussed in relation to possible energy sources during hibernation and the transport of lipids to abdominal fat: pads.
THE EFFECTS OF NEW DIURETICS ON NET ION MOVEMENTS IN SODIUM-RICH SMOOTH MUSCLES
Authors: Daniel E. E.
Published: April 2011

The effects of furosemide, ethacrynic acid, triamterene, and an aldosterone antagonist (Su-11927) were studied on recovery of electrolyte gradients by Na-rich pieces from rabbit uteri and aortas. In sufficient concentration furosemide and ethacrynic acid appeared to inhibit Na extrusion. Only furosemide inhibited K uptake as well. A small concentration of ethacrynic acid (0.1 μg/ml) increased Na extrusion from Na-rich uterine pieces but did not increase K uptake. Thus K gain and Na extrusion were not always reciprocally related. Triamterene and Su-11927 altered recovery of electrolyte gradients, but convincing evidence for inhibition of Na active transport was not obtained. Whether inhibition of Na extrusion without inhibition of K uptake, as by ethacrynic acid, could be considered convincing evidence of inhibition of active transport was discussed.
HYPERTENSION FOLLOWING SUBCUTANEOUS AND INTRAPERITONEAL INJECTIONS OF POLYVINYL ALCOHOL AND THE EFFECT OF ALDOSTERONE
Authors: Hall C. E. , Hall O.
Published: April 2011

Rats given subcutaneous or intraperitoneal injections of polyvinyl alcohol (PVA) for a month developed hypertension after discontinuance of injections. Aldosterone given for a week terminally to severely hypertensive animals neither exacerbated hypertension nor induced the eclamptic manifestations previously noted to occur after more prolonged subcutaneous PVA administration. It is concluded that eclamptic manifestations are not due to increased levels of endogenous salt-retaining steroids. Possible reasons are considered for the customary inability of rats given PVA intraperitoneally to develop hypertension during the course of injections although they readily do so thereafter.Intraperitoneal PVA administration caused the formation of medial and intimal foam cells in cardiac arteries, and an abundant display of giant cells in various organs and tissues. In contradistinction to the earlier findings in animals killed immediately after a course of injections, there was in this study, in which the rats were killed only when a considerable time had elapsed after PVA treatment, no substantial difference in the severity of hepatosplenomegaly between intraperitoneally and subcutaneously injected rats.
MUSCLE RELAXANT ACTIVITY OF CHLORDIAZEPOXIDE AND DIAZEPAM
Authors: Hamilton John T.
Published: April 2011

The effect of chlordiazepoxide and diazepam was studied upon the reflex and non-reflex contractions of the tibialis anterior muscle of the cat (anesthetized with chloralose). Results were obtained which indicate that, under these conditions, the primary muscle relaxant activity is central rather than peripheral. Evidence is presented which suggests that these agents more readily inhibit the contractions due to rapid (60 per minute) rather than slow (12 per minute) rates of reflex stimulation. Experiments on the isolated rat phrenic nerve – diaphragm preparation indicate that these compounds are capable of producing a dose-related inhibition of both directly and indirectly elicited contractions. With this preparation, no rate dependence was observed. An interesting feature was that diazepam was about five times as active as chlordiazepoxide, which is identical with the ratio of activity reported for muscle relaxant activity as tested by the inclined-screen test and anti-strychnine activity in mice, and gross muscular relaxation and spinal reflex blocking activity in cats.
A COMPARISON OF THE EFFECT OF DIETARY FAT AND CARBOHYDRATE ON FREE AMINO ACIDS IN THEBLOOD PLASMA OF CHICKS
Authors: Shao Tsang-Cheng , Hill D. C.
Published: April 2011

As previously reported, an increased concentration of plasma free amino acids, particularly lysine and threonine, was found when chicks were fasted for 24 hours. This increase was suppressed where a nonprotein diet was fed. Dextrose as the chief energy source in the nonprotein diet was more effective than shortening or lard in this respect. However, the degree to which the two energy sources differed was less where birds were adapted to the utilization of fat by feeding a diet rich in fat for a considerable time before making the comparison. Insulin administration to fasted chicks was found to lower plasma amino acid levels. The possible influence of interrelationships among dextrose, fat, and insulin on plasma amino acid levels is discussed.
ACETANILIDE AS A POTENT INHIBITOR OF METHANOL METABOLISM IN MICE
Authors: Hassan A. , Elghamry M. I. , Abdel-Hamid F. M.
Published: April 2011

The effect of acetanilide on the in vivo oxidation of methanol, ethanol, and formate in mice was investigated by using 14C-iabelled substrates and measuring the production of 14C-labelled carbon dioxide in the expired air. The intraperitoneal administration of acetanilide (100 mg/kg body weight) strongly inhibited the oxidation of methanol. When acetanilide was administered 20 minutes before the injection of methanol, degradation of the alcohol during the first 6 hours following its administration was inhibited 42–73%. Under similar conditions, the metabolism of formic acid was reduced to a much smaller extent (about 12%). On the other hand, the drug was without effect on the oxidation of ethanol. It was concluded that methanol and ethanol are metabolized in mice by two different enzymic systems. If it is assumed that methanol is oxidized in the mouse by a catalase–peroxide system, then the mechanism whereby acetanilide inhibits methanol degradation probably involves reduction of the peroxide pool, rather than inhibition of catalase. Acetanilide (100 mg/kg) partially protects mice against lethal doses of methanol, provided that the drug is given 20–60 minutes before methanol is administered.
BLOOD TRANSAMINASE ACTIVITIES IN VITAMIN B6 DEFICIENCY: EFFECT OF DEPLETION AND REPLETION ON THE ERYTHROCYTE ENZYMES
Authors: Cheney M. C. , Sabry Z. I. , Beaton G. H.
Published: April 2011

To assess the usefulness of the erythrocyte transaminases, glutamic–oxaloacetic and glutamic–pyruvic, in the evaluation of vitamin B6 nutritional status, the response of these enzymes to repletion following 1, 4, and 10 weeks of vitamin B6 depletion was compared with that of the plasma and liver transaminases in the rat. The responses of the erythrocyte enzymes reflected the state of vitamin B6 nutrition most accurately and, unlike the plasma and liver transaminases, were not affected by other factors. Repletion produced a rapid response in the erythrocyte enzymes; however, restoration of control levels appeared to depend on red cell turnover, particularly after prolonged depletion periods. This finding suggests that the apoenzyme, as well as the coenzyme, is depleted during vitamin B6 deficiency.
METABOLIC ADJUSTMENTS TO LOW TEMPERATURES IN NEW ZEALAND WHITE RABBITS
Authors: Heroux O.
Published: April 2011

Characteristics of cold acclimation in shaved New Zealand white adult rabbits kept individually at 6 °C for 3–5 weeks were (i) a 40% increase in food consumption, (ii) maintenance of body weight, (iii) a 45% increase in resting metabolism measured at 28 °C, (iv) an almost complete disappearance of shivering, (v) increased cold resistance, (vi) failure to cut off increased heat production when abruptly returned to 28 °C, and (vii) a maximum increase of 41% in oxygen consumption after noradrenaline infusion at 28 °C of doses varying between 1.18 and 9.44 μg/kg per min. Rats acclimated to 6 °C showed a maximum increase of 113% in their oxygen consumption when infused with similar doses of noradrenaline varying between 1.34 and 10.72 μg/kg per min. The conclusion is reached that in rabbits which usually rely on thick fur for protection against cold, the primary metabolic adjustments in these animals when they are shaved are a rise in basal metabolism and an increase of the same order in noradrenaline sensitivity.
THE FATE OF DIMETHYL SULFOXIDE APPLIED TO THE SKIN OF THE RAT
Authors: McDermot H. L. , Finkbeiner A. J. , Zanette B.
Published: April 2011

Dimethyl sulfoxide (DMSO) applied to the skin of the rat has been shown to be more than 90% absorbed with evaporative losses of less than 1%. Following absorption, it was found in the following selected tissues: brain, muscle, kidney, lung, liver, heart, and blood. Peak concentrations in all the tissues were found 1.5 to 2 h after administration of DMSO. The highest concentration was observed in the kidney. Approximately 85% of the applied dose was excreted unchanged in the urine in 24 h.
ACUTE AND CHRONIC INFLUENCE OF DIAZOXIDE ON ADRENAL-REGENERATION HYPERTENSION
Authors: Hall C. E. , Holland O. B. , Hall O.
Published: April 2011

The antihypertensive activity of diazoxide was evaluated in rats with regenerating adrenal glands. The drug was given chronically in the drinking fluid, and also by subcutaneous injection at two intervals during the experiment. For a brief period diazoxide in the drinking fluid was replaced by hydrochlorothiazide. Diazoxide caused detectable sodium retention, despite which it reduced the intensity of hypertension and reduced the incidence, severity, and extent of the accompanying vascular lesions. The substitution of hydrochlorothiazide for diazoxide, or the subcutaneous administration of diazoxide to rats that were then consuming it in the drinking fluid, usually further depressed the blood pressure. It may thus be concluded that maximal blood pressure lowering effects of diazoxide were not achieved by oral ingestion, and that while the drug does afford a significant degree of protection against adrenal-regeneration hypertension it is less effective in this respect than hydrochlorothiazide, possibly because diazoxide causes sodium retention whereas hydrochlorothiazide promotes saluresis.
ROLE OF ACETYLCHOLINE IN CENTRAL VASOMOTOR REGULATION
Authors: Sinha J. N. , Dhawan K. N. , Chandra O. , Gupta G. P.
Published: April 2011

The present study was undertaken to investigate the role of acetylcholine in central vasomotor regulation in dogs. Both acetylcholine and carbachol produced a pressor response on intracerebroventricular (i.c.v.) administration. This response was completely blocked by pretreatment with i.c.v. atropine. Administration of hemicholinium into the lateral cerebral ventricle as well as its topical application to the floor of the fourth ventricle depressed the responsiveness of the medullary vasomotor center. Furthermore, choline, a precursor of acetylcholine, reversed the effects of hemicholinium. It is concluded that acetylcholine has an excitatory role in the medullary vasomotor center.
THE INCORPORATION OF PALMITATE-1-14C BY RAT LUNG IN VITRO
Authors: Naimark A. , Klass D.
Published: April 2011

The incorporation of palmitate-1-14C into various lipid fractions was studied in rat lung in vitro. Most of the radioactivity was found in phospholipid, although in terms of decreasing specific activity the lipids were ranked: free fatty acid (FFA), glycerides, phospholipid. In addition to the usual glycerophosphatides, rat lung contained a substance with some of the chromatographic characteristics of phosphatidyl dimethylethanolamine. In terms of decreasing specific activities the phospholipids were ranked: phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl dimethylethanolamine, phosphatidyl serine plus phosphatidyl inositol, sphingomyelin plus lysophosphatidyl choline. Inhibition of oxidative energy production by hypoxia, cyanide, or low temperature markedly depressed the esterification of palmitate-1-14C. Less marked depression was observed in the absence of exogenous glucose. In all cases the decreased incorporation was associated with an increase in the total and specific radioactivity in tissue FFA. It is concluded that energy-independent exchange reactions are probably of little importance in the incorporation of FFA into esterified lipids of lung tissue. Under conditions of metabolic inhibition the penetration of labelled FFA into the tissue FFA pool does not appear to limit esterification.
EFFECTS OF INORGANIC ANIONS ON THE CONTRACTILITY OF VASCULAR SMOOTH MUSCLE
Authors: Jhamandas K. H. , Nash C. W.
Published: April 2011

Contractile responses of isolated loops of rabbit aorta tissues were first recorded in normal Krebs solution and subsequently in a modified Krebs medium in which chloride ions were substituted with equivalent amounts of one of the foreign anions, Br−, NO3−, I−, SCN−, or SO42−. With potassium sulfate or noradrenaline as the stimulating agent, responses of the tissues exposed to these anions for 1 minute and for 16 minutes were recorded. Potassium-induced contractions were potentiated in the presence of Br−, NO3−, I−, and SCN− ions but were depressed in the presence of SO42− ions. Responses to noradrenaline after 1-minute exposures were depressed in the presence of all the foreign anions whereas those induced after 16-minute exposures were potentiated by Br− and NO2− ions but were still depressed by I−, SCN−, and SO42− ions. The alterations in contractility produced by foreign anions have been attributed to their influence on the binding, release, and rebinding of calcium ions. The differences between responses induced by K2SO4 and noradrenaline in the presence of foreign anions can be related to the utilization of calcium from different binding sites in the cell membrane.
SEMIPERMEABLE AQUEOUS MICROCAPSULES: IV. NONTHROMBOGENIC MICROCAPSULES WITH HEPARIN-COMPLEXED MEMBRANES
Authors: Chang Thomas M. S. , Johnson Linda J. , Ransome Oscar J.
Published: April 2011

Stable nonthrombogenic microcapsules of 4 to 200 μ mean diameter consisting of a protein or detoxifying agent enclosed within thin semipermeable benzal-konium–heparin complexed polymer membranes were prepared. Such microcapsules did not cause clot formation in a nonthrombogenic extracorporeal shunt chamber when perfused for several hours by circulating blood which had normal clotting time. The enclosed enzyme retained its catalytic activity.
COMPARATIVE EFFECTS OF ALDOSTERONE AND HEAT ACCLIMATIZATION ON OXIDATIVE ENZYMES IN RAT TISSUES
Authors: Bedrak E. , Samoiloff V.
Published: April 2011

The activities of several oxidative enzymes of liver, kidney, heart, and muscle tissue were compared in groups of rats treated with aldosterone, exposed to heat stress, and acclimatized to a hot environment. A single intraperitoneal injection of 2 μg D-aldosterone monoacetate/g body weight caused an increase in the activity of liver succinoxidase after 3 h and in kidney and heart succinoxidase after 8 h. Similarly, the activity of cytochrome oxidase was enhanced 8 h after a single injection of the mineralocorticoid. Repeated administration of 2 μg D-aldosterone monoacetate/g body weight for 16 days (chronic aldosterone) elicited a significant decrease (P < 0.05) in liver succinoxidase similar to that in heat stress (P < 0.05) and in acclimatization to a hot environment (P < 0.05). On the other hand, the activity of the succinoxidase of kidney, heart, and muscle tissues was slightly stimulated by the chronic aldosterone treatment, by heat stress, and by heat acclimatization. Although the activity of cytochrome oxidase of the liver and kidney was decreased by the chronic aldosterone treatment, heat stress, and heat acclimatization, there was a slight increase in the activity in that of heart and muscle. Most treatments elicited a marked rise in the activity of kidney xanthine oxidase (P < 0.01), whereas the enzyme activity of liver, heart, and muscle was relatively unaffected.
EFFECTS OF CHRONIC INTAKE OF ETHANOL ON RATE OF ETHANOL METABOLISM: II. INFLUENCE OF SEX AND OF SCHEDULE OF ETHANOL ADMINISTRATION
Authors: Khanna J. M. , Kalant H. , Bustos G.
Published: April 2011

Groups of adult Wistar rats were treated for up to 2 months with ethanol in a total daily dose of 9–12 g/kg, according to one of three different schedules of administration: (a) gavage, with a gradual stepwise increase in dosage, plus additional ethanol in the drinking water; (b) inclusion of ethanol in a liquid diet, with 36% of the calories as ethanol; (c) gavage with large intoxicating doses from the beginning of the experiment. Control animals received equicaloric amounts of sucrose in place of ethanol. Both male and female rats were used in schedule a, but only males in b and c. All three groups showed significant increases in liver alcohol dehydrogenase activity, and males and females responded alike. The increase was smallest and the variations greatest on schedule c. Liver lactic dehydrogenase activity was not affected, except for a decline during the first 2 weeks on schedule c, when the animals lost weight. When pair-feeding was used (schedule b), there was identical weight gain by the alcohol and control groups.
DELAY OR INHIBITION OF CONVULSIONS BY INTRAPERITONEAL INJECTIONS OF DIVERSE SUBSTANCES
Authors: DeFeudis F. V. , Elliott K. A. C.
Published: April 2011

Prior intraperitoneal injections, into mice or rats, of strong solutions of γ-aminobutyric acid, DL-alanine, other amino acids, succinate, or sucrose tend to postpone or prevent convulsions and death caused by the administration of oxygen at high pressure, picrotoxin, or pentylenetetrazol. Sodium chloride solution was not as consistently effective. Protection against strychnine was not obvious. Injections of urea solutions or plain water were not effective. Intraperitoneal injections of the "protective" solutions cause increased osmolarity of the serum and dehydration of the brain; the latter effect may be partly responsible for the elevation of seizure thresholds.
BICYCLE ERGOMETER MEASUREMENT OF MAXIMAL OXYGEN UPTAKE IN CHILDREN
Authors: Cumming Gordon R. , Friesen Werner
Published: April 2011

Seven to 15 maximal exercise tests on a cycle ergometer were done on twenty boys, 11 to 15 years of age, until the work load was sufficiently high that it could not be sustained for 3 min. The mean maximal pulse rate was 202 beats/min, and the mean maximal oxygen uptake was 53.8 ml/kg per min. A plateau of the oxygen uptake curve occurred in only 7 of the 20 subjects, whereas the pulse rate reached a plateau in 13 subjects. On the basis of the pulse rate – work load straight line relationship for submaximal exercise, the intensity of the load that the subjects were able to complete was such that a mean predicted pulse rate of 247 beats/min would have resulted. This information can be utilized to obtain maximal oxygen uptake from a single test in children.
MODIFICATION OF HEXOBARBITAL METABOLISM BY MORRIS HEPATOMA 5123tc
Authors: Hickie R. A. , Kalant H.
Published: April 2011

Slices of the Morris 5123tc "minimum-deviation" hepatoma fail to metabolize hexobarbital in vitro; slices of non-tumorous liver from the host rats metabolize it at a lower rate than liver slices from normal animals. A corresponding in vivo difference is indicated by a prolonged hexobarbital sleeping time in tumor-bearing rats. The prolongation begins only when the hepatoma becomes large enough to show areas of necrosis or ulceration, and increases steadily with further tumor growth. Surgical removal of the tumor restores the sleeping time to normal. Since the tumor is implanted subcutaneously and does not invade the liver, it is suggested that a diffusible product of tumor necrosis is responsible for the impairment of hexobarbital metabolism in the host liver.
THE SILENT PERIOD OF SYMPATHETIC PREGANGLIONIC NEURONS
Authors: Polosa Canio
Published: April 2011

The behavior of single sympathetic preganglionic neurons, during and after repetitive antidromic driving, was studied with extracellular microelectrodes in the cat's spinal cord. It was found that repetitive antidromic excitation of spontaneously active units could produce a subsequent, long-lasting inactivity or "silent period". A similar silent period could be produced by antidromic excitation of units in the acutely isolated and deafferentated, upper thoracic, spinal cord. It occurred whenever the neuron soma had been involved in high-frequency activity. It is concluded that the silent period of sympathetic preganglionic neurons is generated in the spinal cord and is due to accumulation of post-activation depression by the cell bodies of the affected units.
Effect of angiotensin on the response to noradrenaline and sympathetic nerve stimulation, and on 3H-noradrenaline uptake in cat mesenteric blood vessels
Authors: Panisset Jean-Claude , Bourdois Pierre
Published: April 2011

The effect of angiotensin on the response to postganglionic sympathetic stimulation was studied in isolated and perfused cat mesenteric blood vessels. Angiotensin perfusion enhanced the vasoconstrictor response to sympathetic nerve stimulation and shifted to the left the dose–response curve of noradrenaline; this potentiating effect persisted even after a return to an angiotensin-free perfusion medium. In chronically denervated preparations, angiotensin increased the effect of noradrenaline, but no persistence of this effect was observed after a return to angiotensin-free medium. The effect of angiotensin was also studied on the uptake of 3H-noradrenaline by measuring the amount of radioactive amine disappearing from the perfusion medium during its passage through the mesenteric blood vessels or by assaying the accumulated radioactive amine in the tissue after perfusion. Angiotensin significantly inhibited the uptake of 3H-noradrenaline measured by these two methods. It is suggested that angiotensin increases the vasoconstrictor responses to noradrenaline administration as well as to sympathetic nerve stimulation (a) by an inhibitory effect on noradrenaline uptake by nerve endings, and (b) by a facilitation of noradrenaline action directly on the smooth muscle cells.
The hyperpolarizing effect of hydrogen ions on transmembrane potential in frog skeletal muscle
Authors: Mainwood G. W. , Lee S. L.
Published: April 2011

The transmembrane potential of frog sartorius fibers in normal Ringer's solution is increased by a few millivolts following a fall in pH of the external medium. The same result is observed in either a bicarbonate–CO2 or a phosphate buffer system. The hyperpolarizing response is still observed when sodium in the Ringer solution is replaced by choline. Immediately after increasing the external potassium from 2.5 to 10 meq/l this effect is reversed. On changing the external potassium back to 2.5 meq/l the effect returns and is considerably enhanced. Chloride loading by presoaking muscles in isotonic KCl and transferring to sucrose causes a reversal of membrane potential and leads to an exaggerated pH effect. These observations, together with the fact that transmembrane conductance falls at a lower pH, suggest that hydrogen ions act mainly by lowering PCl. When ECl > Em, hydrogen ions will increase transmembrane potential. This effect may form the basis of a local control mechanism by which cell activity and local metabolic conditions regulate transmembrane potential.
A comparison of the amino acid concentrating ability of the kidney cortex of newborn and mature rats
Authors: Webber W. A. , Cairns J. A.
Published: April 2011

It has frequently been demonstrated that there are multiple mechanisms for amino acid transport and that these function to maintain a favorable intracellular level of amino acids within cells. In some instances they also make possible the transport of amino acids from one face of a cell layer to the other. In general, developing tissues have a higher concentrating ability than mature tissues. In the kidney, however, it has been observed that the ability to reabsorb amino acids may be less effective in developing than in mature organisms. Studies were carried out to determine whether the newborn rat kidney cortex differed from mature cortex in its ability to concentrate a representative group of amino acids. In general, the patterns observed for the concentrative uptake of glycine, L-leucine, α-aminoisobutyric acid, L-aspartic acid, and L-lysine were the same. In all cases uptake was initially more rapid in the mature tissue, but the concentration ratios ultimately reached were higher in the newborn tissues. It is concluded that, as in other developing tissues, newborn rat kidney cortex has a high concentrating ability and might therefore be expected to reabsorb amino acids at least as effectively as mature cortex. However the observation that uptake is relatively slow initially suggests that although the ability to establish a gradient at equilibrium is high the capacity of the system is relatively low and this may account for the apparent low capacity of the immature kidney to reabsorb amino acids.
Heat tolerance of the resting and exercising rat
Authors: Robinson Sumner M. , Blatt William F. , Teplitz Carl
Published: April 2011

Exercising and non-exercising Sprague–Dawley rats were exposed to ambient temperatures between 35 °C and 60 °C, in 5 °C increments. Tympanic and (or) intraperitoneal temperatures were used as indices of body temperature. Mean survival times were 156 min (45 °C) to 21.8 min (60 °C) for the non-exercising rats and 94.8 min (40 °C) to 15.1 min (60 °C) for the exercising groups. It would appear that the treadmill exercise (32 ft/min for alternate 5-min periods throughout the heat exposure) approximated a 5 °C ambient heat load in that the survival times of non-exercising rats were equivalent to the times of exercising rats exposed at a 5 °C lower ambient temperature. Tympanic temperatures recorded at death showed a progressive increase, from 43.8 °C at 40 °C ambient (exercising) to 47.1 °C and 46.9 °C for non-exercising and exercising rats at 60 °C. Circulatory collapse following marked increases in cardiac rate and blood pressure was documented for non-exercising rats at 45 °C ambient.
Metabolism of inorganic selenium in rumen bacteria
Authors: Hidiroglou M. , Heaney D. P. , Jenkins K. J.
Published: April 2011

In vitro and in vivo experiments demonstrated that rumen bacteria were capable of metabolizing inorganic 75Se and incorporating the element into the microbial protein. The fixation of 75Se into bacteria in vitro was inversely proportional to the previous dietary intake of selenium by the host sheep. In sheep fed a purified diet low in selenium and vitamin E, selenium supplementation caused a marked alteration of the rumen microorganisms. Characterization of the 75Se-containing compounds in the rumen bacteria protein hydrolysates revealed the presence of 75Se-selenomethionine and 75Se-selenomethionine selenoxide.
The chronic oral toxicity of paracetamol at the range of the LD50 (100 days) in albino rats
Authors: Boyd Eldon M. , Hogan Susan E.
Published: April 2011

The LD50 (100 days) ± S.E. (oral dose of paracetamol which killed 50% of young male albino rats when given daily for 100 days) was found to be 0.77 ± 0.02 g/kg per day. The maximal LD0 (100 days) was estimated to be 0.4 g/kg per day, and the minimal LD100 (100 days) 1.1 g/kg per day. Signs of toxicity at the LD0 (100 days) were hyperreflexia, aciduria, hypertrophy of the cardiac stomach, atrophy of the testes, minor degrees of hepatic necrosis and nephritis, and augmented susceptibility to infection. Signs at the LD50 (100 days) were listlessness, pallor, inhibition of growth, diuresis, aciduria, a stress reaction, testicular atrophy, hepatic necrosis, tubular and calyxial nephritis, augmented susceptibility to infection, dehydration, and capillary–venous congestion of many body organs. Doses at and above the minimal LD100 (100 days) produced a toxicity syndrome which included in addition anorexia, hypothermia, hyporeflexia, prostration, and degenerative changes in several body organs. The abrupt withdrawal of paracetamol in survivors at 100 days was followed by a minor abstinence syndrome, with recovery within 2 weeks apart from residual testicular atrophy.