bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF EPINEPHRINE AND COMPETITION BETWEEN MALES ON THE IN VITRO METABOLISM OF RABBIT TESTIS
Authors: Ewing L. L. , Noble D. J. , Ebner K. E.
Published: April 2011

An investigation was conducted to test the effect of stress for periods of 3, 5, and 10 days on metabolic activity in vitro, testis weight and morphology and protein, ribonucleic acid (RNA), deoxyribonucleic, acid (DNA) and cholesterol content of the testis. The two stressors (epinephrine injection and competition between males) caused an increased oxygen uptake in vitro in both testis and kidney cortex slices. This was associated with decreased glucose uptake and no change in lactic acid production in both tissues. There was no significant change in protein, RNA, DNA, and cholesterol content of testis due to stress within the 10 day period. Also, the stressors did not alter significantly testis weight, percent dry matter, or morphology. These data indicate that stress for 10 days does not have any significant effect on testis morphology and size but does cause significant alterations in metabolic activity of testis and kidney cortex slices.
EXCRETION OF CATECHOL AMINES BY WHITE RATS IN THE COLD
Authors: Smith Lorraine C. , Dugal L.-P.
Published: April 2011

Exposure of white rats to 2 °C for 20 weeks caused an immediate and sustained increase in the excretion of catechol amines as compared to controls kept at 23 °C. Adrenaline excretion increased approximately three to four times while noradrenaline excretion increased about eight times. There were no marked differences between Wistar and Sprague–Dawley rats in the amounts of adrenaline and noradrenaline excreted at 23 °C or 2 °C. 'Old' rats kept in activity cages excreted much more of the catechol amines both at 23 °C and 2 °C than did the other rats and they showed a peak for adrenaline excretion after 1 week and for noradrenaline excretion after 3 to 4 weeks in the cold.
A DYNAMIC ANALYSIS OF THE MECHANISMS INVOLVED IN ACUTE ACTIVATION OF THE PITUITARY–ADRENOCORTICAL COLD
Authors: Jonec Viliam
Published: April 2011

The participation of the psychic or the somatic component in an acute cold exposure of rats was followed more exactly than before by means of a simple device—the "microclimator"—which allows immediate temperature changes in the experimental environment to be made without altering any of its remaining parameters. Changes in adrenocortical response were followed dynamically in the course of 1 to 6 repetitions of individual stimuli by means of three indicators measured simultaneously (left adrenal ascorbic acid, right adrenal corticosterone, and peripheral plasma corticosterone). A marked dissociation in the adrenal response to psychic stress was found according to adrenal ascorbic acid depletion and (or) corticosterone changes in plasma and the adrenal. In addition, a favorable adaptation effect of the psychic component on the complex acute cold exposure was found in the responses of the adrenal cortex to single as well as repeated exposures.
ACUTE AND CHRONIC EFFECTS OF THE INSECTICIDE ENDRIN ON RENAL FUNCTION AND RENAL HEMODYNAMICS
Authors: Reins D. A. , Holmes D. D. , Hinshaw L. B.
Published: April 2011

Variable effects of chlorinated hydrocarbon insecticides on the kidney have been reported. The purpose of the present study was to determine the acute and chronic effects of the insecticide endrin on renal function and hemodynamics in dogs. Dogs were exposed to endrin acutely by intravenous infusion, and chronically by intramuscular injection. In acute experiments, dogs developed systemic hypertension and increased renal vascular resistance attributable to a sympatho-adrenal action. Acute effects of endrin were predominantly afferent arteriolar vasoconstriction as evidenced by decreases in renal blood flow, glomerular filtration rate, and urine flow. Phentolamine and phenoxybenzamine increased renal blood flow after endrin, providing evidence for humorally induced renal vasoconstriction due to adrenergic agents. Adrenalectomy partially offset the marked drop in renal blood flow after endrin although systemic hypertension and bradycardia were unaffected. Results from renal denervation experiments were variable. Changes in renal function in chronic studies were minimal and appeared to be due to secondary alterations in systemic hemodynamics. Results from this investigation provide no evidence for renal failure attributable to the direct effects of endrin.
HEXAFLUORODIETHYL ETHER (INDOKLON) CONVULSIONS IN CORPUS-CALLOTOMIZED WHITE RATS
Authors: Butler H. R. , Manax S. J. , Stavraky G. W.
Published: April 2011

The convulsant threshold of 24 corpus-callotomized Sprague–Dawley rats exposed to Indoklon vapor once a week was found to be significantly lower than that of 24 sham-operated controls in the second, third, and fourth exposures; the sensitivity of both groups of animals increased progressively and levelled out at the fifth exposure. Repetition of the experiment after 3 weeks of rest, with exposures spaced at 48-hour intervals, further lowered the convulsant threshold of the animals, both groups exhibiting a similar, and possibly maximal, sensitivity to Indoklon at the second exposure. When in another series, 60 corpus-callotomized rats and 60 sham-operated controls were injected intraperitoneally with CD10 of Indoklon at weekly intervals, the susceptibility of both groups to convulsions again increased rapidly during the first four injections; at the second injection, the corpus-callotomized rats were significantly more sensitive to Indoklon than the controls. During the fifth to eighth injection, the convulsibility of the animals reached a plateau, 62.2% to 78.5% of the rats convulsing; the difference between the two groups at this stage became less marked, though the convulsions in corpus-callotomized animals continued to be of longer duration than in the controls. Repetition of the injections, spaced at 48-hour intervals, after 3 months of rest, demonstrated a continuing high and equal sensitivity of the two groups of rats to Indoklon with some depression setting in during the second half of a series of 12 injections.
ON THE RELATIONSHIP BETWEEN TESTICULAR BLOOD FLOW AND SECRETION OF TESTOSTERONE IN ANESTHETIZED DOGS STIMULATED WITH HUMAN CHORIONIC GONADOTROPHIN
Authors: Eik-Nes Kristen B.
Published: April 2011

The concentration of testosterone has been measured in spermatic vein blood from the left testis in 25 anesthetized dogs, stimulated with human chorionic gonadotrophin and infused with arterial blood via the left spermatic artery at different rates. The secretion of testosterone varied with the rate at which arterial blood was infused and at a constant infusion rate of 3.81 ml/min, animals weighing from 19 to 23 kg produced testosterone at a constant rate over 90 minutes. Infusion rates lower than this decreased the secretion of testosterone, and if arterial blood was infused at a rate of 0.76 ml/min for the first 30 minutes of experimentation, the capacity of the infused testis to secrete testosterone in the ensuing 60 minutes was impaired even in animals given large doses of human chorionic gonadotrophin via the left spermatic artery. A relationship between the arterial blood flow to the testis and its ability to secrete testosterone under the influence of human chorionic gonadotrophin is thus established.
BIOGENIC AMINES AND FECUNDITY OF TRIBOLIUM CONFUSUM DUVAL (COLEOPTERA)
Authors: Leblanc J. , Villeneuve J. L. , Lemonde A.
Published: April 2011

Aminoguanidine, a histaminase inhibitor, was found to increase fecundity of Tribolium confusum (Coleoptera) when added as a supplement to the basal diet in concentrations of 0.01 and 0.5%. On the other hand alpha-methyl dopa, a decarboxylase inhibitor, had no effect on larval development except at a concentration of 1% where it was shown to be highly toxic. No catechol amines were found in adults of this species, but histamine was always detected and reached higher levels in insects fed higher concentrations of aminoguanidine. These results suggest a possible role for histamine in insect reproduction.
THE EFFECT OF COLD EXPOSURE ON PLASMA AND LIVER CHOLESTEROL LEVELS IN RATS FED VARIOUS DIETS
Authors: Wood J. D.
Published: April 2011

Plasma and liver cholesterol levels were compared in male Wistar rats kept at environmental temperatures of 2 °C and 23 °C on various dietary regimens. Cold exposure had little or no effect on the tissue cholesterol levels provided the diet contained appreciable amounts of choline and inositol, the only statistically significant change observed being a small difference in the liver cholesterol concentration in rats maintained on a cholesterol-free diet. A choline- and inositol-deficient diet produced a hypocholesterolemic effect in rats at 23 °C but this effect was counteracted by exposing the rats to a cold environment. The possible significance of this observation with regard to the biochemical defect in "choline deficient" fatty livers is discussed.
SOME EFFECTS OF PHLORIZIN AND PHLORETIN ON RENAL AMINO ACID REABSORPTION IN THE DOG
Authors: Webber William A.
Published: April 2011

The effects of phlorizin and phloretin on amino acid reabsorption were studied using clearance techniques in dogs. At endogenous plasma amino acid concentrations no effects were demonstrable. At elevated amino acid levels phlorizin depressed the reabsorption of L-aspartic acid and L-lysine. Phloretin depressed the reabsorption of L-aspartic acid but had a slight enhancing effect on that of L-lysine. No definite effects were observed on L-alanine or glycine reabsorption. These results are not predictable from the observations of other workers that in the in vitro rat kidney cortex phlorizin increases amino acid concentrating ability while phloretin depresses it. Our results are not, however, incompatible with the in vitro observations since it is theoretically possible for an agent to enhance the concentrating ability of kidney cortex, and either depress or increase tubular reabsorption, depending on whether the predominant site of action is on the luminal or basal side of the proximal tubular cells.
THE DEPOSITION OF AEROSOLS IN THE RESPIRATORY TRACT: I. MATHEMATICAL ANALYSIS AND COMPARISON WITH EXPERIMENTAL DATA
Authors: Beeckmans J. M.
Published: April 2011

The deposition of aerosol in the human respiratory tract was calculated as a function of the particle size and particle density of the aerosol, the manner of breathing, and various parameters which control the degree of mixing of inspired air with the dead space air and with the lung air. The computations were performed on an electronic computer, which allowed a full analysis of the effects of the various parameters. Agreement between the computed total deposition curves, and published experimental data was very satisfactory. The computed curves exhibited the minimum in total deposition previously established experimentally, in the region of 0.3 μ. The maximum in the alveolar deposition curve was about 1 μ for particles of unit density, confirming the results of Brown, Cook, Ney, and Hatch for nose breathing. Its position was a function of the density of the aerosol particles, but was relatively insensitive to the tidal volume and other breathing parameters. The opposite held in regard to the value of the maximum, which was totally uninfluenced by the particle density, but was affected by the breathing parameters.
STUDIES ON THE MECHANISM OF EXPERIMENTAL SOFT-TISSUE CALCIFICATION
Authors: Gabbiani G. , Tuchweber B.
Published: April 2011

Sodium phosphate increases, while calcium acetate inhibits, the calcium precipitation normally induced by calcergy in the rat. Presumably, phosphates play the leading role in the production of this type of calcification.
EFFECTS OF SPINAL SECTION AND RENAL DENERVATION ON THE RENAL RESPONSE TO BLOOD VOLUME EXPANSION
Authors: Pearce J. W. , Sonnenberg H.
Published: April 2011

Expansion of the blood volume with "artificial blood" infusion, previously shown to cause diuresis and natriuresis in anaesthetized dogs, failed to produce this renal response in chronic high-spinal dogs. This observation was considered best explained as the result of interruption of nervous pathways essential to a reflex mechanism. In other dogs, unilateral renal denervation did not significantly alter the time course of response or the magnitude of the diuresis, but did result in a reduced natriuresis. As there was no qualitative difference between the responses of the innervated and denervated kidneys in each animal, it is concluded that renal motor nerve supply is not involved in the effector limb of the reflex, which must then be humoral. Bilateral renal denervation led to a marked reduction in natriuretic response to infusion and, while not reducing the diuretic response, significantly delayed the maximum increase in urine flow. These effects, like those of spinal section, are attributed to the loss of sensory pathways. The hypothesis is advanced that receptors of extracellular fluid volume with spinal afferent pathways exist in the kidney and also in some extrarenal site, and that their activity is necessary to facilitate response of central nervous centers to increased discharge of receptors of intravascular volume.
THE EFFECTS OF CONTINUOUS INFUSION OF ETHANOL INTO THE PORTAL SYSTEM OF THE RAT
Authors: Kaneko M. , Rappaport A. M. , Lucas C. C.
Published: April 2011

A technique for the continuous infusion of 10% v/v ethanol in physiological saline into the portal vein of rats for periods up to 4 weeks is described.Measured amounts of pure alcohol were thus delivered directly to the liver cells by the portal blood continuously for weeks, providing up to 10% of total calories but avoiding inebriation. In the livers of well-nourished rats no histological abnormality attributable to prolonged exposure to alcohol was noted.
PROSTAGLANDINS IN BRAIN AND THE RELEASE OF PROSTAGLANDIN-LIKE COMPOUNDS FROM THE CAT CEREBELLAR CORTEX
Authors: Coceani F. , Wolfe L. S.
Published: April 2011

A water-soluble lipid material resistant to acid and alkali treatment was found in perfusates and extracts of brain tissue, which induced contraction of the 'slow type' on the isolated rat stomach fundus. The material isolated from brain tissue extracts behaved in solvent partition systems like the prostaglandin compounds and could be purified by silicic acid and thin-layer chromatography. The smooth-muscle-stimulating activity is likely due to the trihydroxyprostaglandin compounds.
FAILURE OF THE METHOD OF PARALLEL BIOASSAY TO IDENTIFY ACETYLCHOLINE IN MIXTURES OF SUBSTANCES WITH ACETYLCHOLINE-LIKE ACTIVITY
Authors: Hosein E. A. , Koh Teow Yan
Published: April 2011

The method of parallel bioassay used on the sensitized frog rectus, the dorsal muscle of the leech, the guinea pig ileum, and the cat's blood pressure has been studied to determine whether this method permits the identification of acetylcholine in mixtures of substances which possess acetylcholine-like activity. It was found that the method cannot identify acetylcholine in such mixtures, and in addition, the data obtained indicated that the method also failed to identify other substances with similar pharmacological activity, which were present in the mixtures. It was concluded that the method of parallel bioassay cannot be used to identify acetylcholine in extracts unless it is shown by other means that acetylcholine is the only active substance present in the material being assayed.
A TETRACYCLINE-BASED EVALUATION OF THE RELATIVE PREVALENCE AND INCIDENCE OF FORMATION OF SECONDARY OSTEONS IN HUMAN CORTICAL BONE
Authors: Takahashi Hideaki , Frost Harold M.
Published: April 2011

In mineralized sections of 160 adult human bones, the relative prevalence of three major kinds of secondary osteons was compared with the relative incidence with which they were formed, the latter with the aid of bones that had been marked in vivo with tetracycline antibiotics. Relative prevalence and incidence were similar, implying that the biological lifetimes of the three osteon types are similar. Unremodeled secondary osteons were about 90% of the total osteon population, and also of the labelled-bone forming sites. Each of the 822 tetracycline-labelled foci of bone formation that were found inside the cortices of various bones belonged to one of the three osteon types that were studied, and no other kinds of labelled sites were observed. This implies that osteonal remodeling is the major mode of osteoblastic activity inside of cortical bone.
ALPHA-2-MACROGLOBULIN AND THE QUESTION OF A PROTEIN CARRIER FOR INSULIN IN HUMAN SERUM
Authors: Geerling Herbert , Sirek Otakar V.
Published: April 2011

Blood serum from presumably normal individuals was investigated for its insulin-I131 binding capacity by Immunoelectrophoresis and subsequent radioautography, by immunoprecipitation in the test tube, and by preparative ultracentrifugation.Binding of radioactive insulin to alpha-2-macrogiobulin was demonstrated by immunoelectrophoresis, but the fact that radioactivity was present also in a number of other protein precipitates weakened the argument for a specific insulin carrier in blood. Nonspecific trapping of radioactive material may have occurred in the course of formation of protein precipitates in agar gel because immunoprecipitates produced in the test tube with the same polyvalent antiserum did not contain appreciable amounts of radioactivity.Results of experiments in the preparative ultracentrifuge indicated that neither multiple dilutions nor addition of pure human alpha-2-macroglobulin to serum produced measurable differences in the distribution of radioactivity following incubation and spinning with a constant amount of insulin-I131.The results of these studies do not lend support to the concept of alpha-2-macroglobulin being a specific protein carrier of insulin in blood.
DEPRESSED DIURESIS CAUSED BY ETHANOL AFTER A WATER LOAD IN RATS
Authors: Chaudhury R. R. , Chaudhury M. Roy , Lu F. C.
Published: April 2011

Ethanol at 5% and 10% depresses the absorption and excretion of a water load in rats. This depression of diuresis is probably caused by the ethanol-induced acidity, since it was not observed when the gastric acidity was neutralized by administration of aluminium hydroxide concomitant with the ethanol.
RESTORATION OF HEPATIC AND MAMMARY GLAND HEXOSEMONOPHOSPHATE SHUNT ACTIVITY IN THE ADRENALECTOMIZED LACTATING RAT BY ADRENAL CORTICOIDS
Authors: Willmer J. S. , Foster T. S.
Published: April 2011

A comparison of the ability of various steroids to maintain normal levels of mammary gland and liver hexosemonophosphate shunt enzymes, and to promote normal growth rates in the litters of adrenalectomized rats, showed the glucocorticoids, hydrocortisone, cortisone, and corticosterone to be most effective. Deoxycorticosterone was effective at a high dose level, but 11-deoxy-17-hydroxy-corticosterone and progesterone had very little influence upon hepatic glucose-6-phosphate dehydrogenase. Combinations of deoxycorticosterone with a glucocorticoid were no more effective than the latter alone. A postoperative delay of up to 10 days apparently did not cause changes which impaired the ability of the animals to react to hydrocortisone or cortisone; increased enzyme levels and litter weights were demonstrable under these conditions.
EFFECTS OF AMINO ACIDS ON RENAL GLUCOSE REABSORPTION IN THE DOG
Authors: Webber William A. , Campbell John L.
Published: April 2011

The effects of intravenous amino acids on maximal renal tubular reabsorption of glucose were studied in dogs by clearance techniques. L-Lysine, glycine, and L-alanine caused a significant depression of glucose reabsorption whereas L-aspartic acid and L-leucine did not. These results support other evidence that there is a relationship between the transport mechanisms for a variety of substances such as simple sugars, amino acids, and phosphate in the kidney. The effects, however, are probably not competitive but may depend on some indirect action on net transport such as altered membrane permeability or intracellular osmotic pressure. Incidentally, it was noted that L-aspartic acid, L-lysine, glycine, and L-alanine infused along with glucose resulted in significantly less elevation in plasma glucose concentration than that observed when the same amount of glucose was infused alone. The effects of amino acids on plasma glucose confirm earlier reports that mixtures of amino acids depress elevated blood sugar levels. These effects were found to occur with basic, acidic, and neutral amino acids. The method of action of amino acids in influencing plasma glucose has not been determined, but it may be similar to known effects of leucine, which is thought to induce hypoglycemia, particularly in sensitive individuals, by increasing insulin output.
THE EFFECTS OF ESTROGEN AND ANDROGEN ON OSMOTIC FRAGILITY AND FATTY ACID COMPOSITION OF ERYTHROCYTES IN THE CHICKEN
Authors: March B. E. , Coates V. , Biely Jacob
Published: April 2011

Breed and sex differences were observed in erythrocyte counts in the chicken. A difference in osmotic fragility of erythrocytes was found between chickens of the New Hampshire and White Leghorn breeds. Erythrocytes from mature males were more susceptible to osmotic hemolysis than were erythrocytes from mature females. Lipids extracted from ghosts of erythrocytes from mature females or from males treated with diethylstilbestrol contained a higher proportion of oleic to stearic acid than did those from male birds. Incubation of erythrocytes in plasma derived from birds of the opposite sex increased the osmotic stability of ceils from males and decreased the stability of cells from females in comparison with the stability of erythrocytes incubated in autologous plasma.
RESPONSE OF ISOLATED LIVER TO ENDOTOXIN
Authors: Hinshaw Lerner B. , Reins Dale A. , Hill Ronald J.
Published: April 2011

The present investigation was carried out to study the vascular responses of the canine liver to endotoxin. Isolated denervated livers were continuously weighed and perfused via arterial and venous inflow vessels. Significant increases in hepatic artery and portal vein pressures, resistances, and organ weights were observed after endotoxin. Vascular responses were not blocked by phentolamine or duplicated by injections of suspected vasoactive agents. Responses to endotoxin and 48/80 were not blocked by phenoxybenzamine, although the vasoconstriction resulting from epinephrine and histamine administration was obliterated. The liver vascular response to endotoxin was duplicated by increasing hepatic vein pressure by partial outflow obstruction. Evidence points to the intrahepatic venous system as the primary site of endotoxin action with a subsequent myogenic response in the hepatic arterial segment.
INHIBITION BY CORTISOL OF ACTH RELEASE FROM ANTERIOR PITUITARY TISSUE IN VITRO
Authors: Pollock John J. , LaBella Frank S.
Published: April 2011

The central basophilic region of bovine anterior pituitary glands was incubated for 30 minutes with varying concentrations of cortisol. Dialyzed incubation medium was subsequently assayed for ACTH activity by measuring the increased production of steroids from bovine adrenal cortex slices. Inhibition of ACTH release was evident with 5.5 × 10−11 M cortisol, but was more pronounced and consistent with 5.5 × 10−8 M or higher. Concentrations of 5.5 × 10−6and 5.5 × 10−5 M were generally less effective in causing inhibition of ACTH release than were concentrations of 5.5 × 10−8and 5.5 × 10−7 M.
THE INFLUENCE OF SYMPATHOMIMETIC AMINES, MONOAMINE OXIDASE INHIBITORS, AND ANTIHYPERTENSIVES UPON THE ENERGY METABOLISM IN THE RAT HEART
Authors: Hilliard W. G. , Oliver W. T. , Petten G. R. Van
Published: April 2011

This investigation was undertaken to determine the effects of three classes of catecholamine-releasing drugs on cardiac energy metabolism. The levels of adenosine monophosphate (AMP), adenosine diphosphate (ADP), adenosine triphosphate (ATP), inorganic phosphate (IP), and phosphocreatine (CP) of the rat heart were measured. The sympathomimetic amines tyramine, ephedrine, methylamphetamine, and (+)- and (−)-amphetamine caused significant decreases in CP. Tyramine and (+)- and (−)-amphetamine also significantly depressed ATP. Of the antihypertensive drugs investigated, bretylium and guanethidine decreased the amount of CP present, and the latter compound also significantly decreased ATP. The administration of reserpine was without significant effect on cardiac high-energy phosphate levels. Among the monoamine oxidase inhibitors, tranylcypromine significantly lowered ATP and CP, whereas pheniprazine produced no significant changes. This study showed that those drugs which have been reported to release cardiac catecholamines also reduced cardiac levels of CP and ATP. The hypothesis is advanced that this effect is due to increased utilization of energy by two mechanisms: (a) stimulation of the active recapture mechanism for adrenergic neurotransmitters, and (b) the positive inotropic and chronotropic responses of the heart to the drug-released catecholamines. In either case, the observed decreases in the levels of ATP and CP in the heart are effects of sympathomimetic amines which have been heretofore unreported.
GLYCEMIA AND CONSECUTIVE PASSIVE TRANSFERS OF AN ANAPHYLACTOID REACTION INDUCING FACTOR IN RATS
Authors: Adamkiewicz V. W. , Sacra P. J.
Published: April 2011

Intravenous injection of a shock dose of dextran (12 mg/100 g body weight) into Sprague–Dawley rats sensitized 8 days previously (with 30 mg/rat intraperitoneally) caused, within 1 hour, an anaphylactoid reaction as well as the appearance in serum of an anaphylactoid reaction inducing factor that was shown to be different from the original dextran. Hypoglycemic rats (insulin–Zn, 2 units/100 g) produced enough of this factor to enable its passive transfer in serum (0.5 ml/100 g intravenously), at hourly intervals, through three consecutive groups of hypoglycemic rats, each time causing anaphylactoid reaction. Hyperglycemic rats (having received 8 millimoles D-glucose/100 g per os, or with alloxan diabetes) produced less of the factor, so that it could be transferred to only one group of hypoglycemic rats. Production of the factor, therefore, is inhibited in the presence of high blood sugars. When transferred to hyperglycemic rats the factor produced no anaphylactoid reaction, but on further transfer to hypoglycemic rats, it produced the reaction. Production of an anaphylactoid reaction by the factor is therefore reversibly inhibited in the presence of high blood sugars.
THE EFFECT OF CORONARY VASODILATATION (DIPYRIDAMOLE-INDUCED) ON THE MYOCARDIAL DISTRIBUTION OF TRITIATED WATER
Authors: Palmer Wilfred H. , Fam Wadie M. , McGregor Maurice
Published: April 2011

The uptake of tritiated water in the left ventricle has been studied during constantly increasing concentrations of tritium in two groups of normal dogs, one of which received dipyridamole intravenously while the other acted as control. Dipyridamole administration was associated with a 1.6 times greater coronary flow and an appropriate reduction in arterial coronary sinus oxygen difference. As judged by the concentrations of indicator in different myocardial samples the perfusion of the myocardium of the normal dog is relatively homogeneous. No differences were detected between the inner and outer half of the ventricular wall or between the apical region and the free wall of the left ventricle. Comparison of myocardial and coronary sinus concentrations of tritium indicated that the increased coronary flow following dipyridamole was the result of an increase in the effective capillary flow rather than a shunting through diffusion-limited pathways, such as would occur in functional or anatomical arterio–venous shunts.
EFFECTS OF PERFUSION MEDIA ON THE Ca++ AND Mg++ CONTENT OF RAT LIVER
Authors: Hickie R. A. , Kalant H.
Published: April 2011

Normal adult male rats were injected with 45CaCl2 intraperitoneally, and radioactivity in whole blood and liver was assayed at intervals of 10 minutes to 48 hours; the results showed rapid equilibration of 45Ca in the liver. In different animals, hepatic perfusion was carried out 4 hours after intraperitoneal injection of 45CaCl2. Portal perfusion with 100 ml of Krebs–Ringer phosphate (KRP) solution removed over 90% of the 45Ca from the liver, and addition of 0.5% EDTA to the solution did not alter the amount removed, although it resulted in earlier 45Ca washout. In other groups of rats, Ca++ and Mg++ concentrations were measured by atomic absorption spectrophotometry in samples of unperfused liver, and livers perfused with various media. Perfusion with KRP had little effect, but KRP + EDTA removed 60% of the Ca++ and 10% of the Mg++, whereas Ca++- and Mg++-free KRP removed 76% of the liver Ca++ but only 4% of the Mg++. It is concluded that tissue Ca++ is extremely loosely bound, and that EDTA effects on cell adhesion and permeability are due primarily to removal of tissue Ca++.
THE EFFECT OF LOCAL COOLING ON THE SENSITIVITY TO NORADRENALINE OF VESSELS IN THE FEET
Authors: Gaskell Peter , Bray Garth M.
Published: April 2011

Local cold markedly reduces the rate of blood flow in the extremities. Experiments were performed to see whether it also increased the sensitivity of vascular smooth muscle to noradrenaline in terms of a reduced threshold dose. Rate of blood flow in the feet was measured by venous occlusion plethysmography. The plethysmographs were filled with water at 21 °C for the left foot and 34 °C for the right. Noradrenaline in doses of 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 μg/minute were infused intravenously for periods of 5 to 7 minutes. Rate of flow during noradrenaline infusion was expressed as a percentage of the rate just before noradrenaline. Fifteen experiments on 13 subjects were performed but not all doses were administered in each experiment. The mean of the percentage flow rates for all infusions at a given dose of noradrenaline was not less than 100% for either foot until 0.8 μg/minute was administered, when flow was reduced in both warm and cool feet. Thus, cooled vessels were not shown to be more sensitive than warm vessels. Noradrenaline infused at 3.2 μg/minute caused a significantly greater reduction in flow rate in the cool than in the warm feet but this is not interpreted as a greater reactivity of the cooler vessels to the drug.
CHANGES IN THE SENSITIVITY OF X-IRRADIATED MICE TO BACTERIAL ENDOTOXIN
Authors: Vittorio P. V. , Watkins E. A. , Dziubalo-Blehm S.
Published: April 2011

When endotoxin was injected into mice 4 to 24 hours after X-irradiation the LD50/3 was increased from 500 μg (non-irradiated control) to 715 μg and 825 μg respectively. Administration of different doses of X-irradiation showed that increasing the dose from 200 to 600 R caused a linear increase in the endotoxin LD50 of mice and it was in the order of 100 μg per 200 R. From 800 R to 1400 R there was a decrease in the endotoxin LD50 of mice, but only the 1400-R dose produced a lower LD50 than that in the non-irradiated control. Since whole-body counter studies with 51Cr-labelled endotoxin showed that X-irradiation did not change endotoxin excretion, increased endotoxin LD50 values 4 and 24 hours after X-irradiation were not due to increased rates of endotoxin excretion.
EFFECT OF FORCED RESTRAINT ON HEART PHOSPHOLIPIDS
Authors: Prioreschi P. , Peterman E.
Published: April 2011

The cardiac level of phospholipids and their fatty acid composition were measured in the rat after different periods of forced restraint and different periods of rest. After 4 minutes of forced immobilization the level of heart cardiolipin decreased by about 75%. When the animal was immobilized for 24 hours the concentration of cardiolipin in the heart returned to normal after less than 96 hours of rest. The concentration of sphingomyelin was also decreased by forced restraint whereas phosphatidyl ethanolamine decreased only in the resting period after immobilization. The significance of these findings in the pathogenesis of experimental cardiac necroses is discussed.
THE INFLUENCE OF METHIMAZOLE ON THE CATECHOLAMINE EXCRETION OF COLD-STRESSED RATS
Authors: Johnson G. E. , Flattery K. V. , Schönbaum E.
Published: April 2011

The exposure of the albino rat to a cold environment (4 °C) results in both an increased urinary excretion of noradrenaline and an increased thyroid activity. Failure of the animal to secrete adequate amounts of noradrenaline or, in its absence, adrenaline, results in hypothermia and death. The influence of thyroid activity on the secretion of catecholamines and the maintenance of metabolic rate and body temperature in cold-stressed rats was investigated. Cold-acclimated rats kept at 4° were fed the antithyroid drug methimazole (0.1% in the drinking water) for 3 weeks. The excretion of free adrenaline and noradrenaline doubled. A parallel increase in normetanephrine excretion suggested an increased catecholamine secretion. Both body temperature and metabolic rate dropped on the third week. A similar experiment done on normal rats placed at 27° showed that methimazole failed to alter catecholamine excretion in the warm environment. It is postulated that the increase in secretion of adrenaline and noradrenaline at 4° resulted from a decrease in the intrinsic metabolic activity of the catecholamines and is a compensatory mechanism for maintenance of heat production.
ANTAGONIZING ACTION OF CHLORPROMAZINE, DIBENAMINE, AND PHENOXYBENZAMINE ON POTASSIUM-INDUCED CONTRACTION
Authors: Shibata Shoji , Carrier Jr. Oliver
Published: April 2011

When rabbit aortic strips were incubated for 1 hour in Ringer's solution containing 10−5 M chlorpromazine, 10−4 M Dibenamine, or 10−4 M phenoxybenzamine, or 2 hours in calcium-free Ringer's solution, they failed to respond to high potassium (10–80 mM). With increasing external calcium this inhibitory action on the potassium-induced contraction decreased. Incubation in solutions containing 10−4 M phentolamine, dihydroergotamine, yohimbine, azapetine, pronethanol, dichloroisoproterenol, or MJ 1998 did not inhibit the response to potassium. The responses to angiotensin (5 × 10−7 M) were not antagonized by any of the blocking agents. It was found that the three agents blocking the potassium-induced contraction inhibited calcium-45 uptake during these contractions; however, they did not inhibit the calcium-45 uptake of unstimulated muscle. The other agents tested failed to decrease the calcium-45 influx during potassium contraction. There were no tissue electrolyte changes found after treatment of the aortas with any of the agents. The results suggest that the inhibition observed was mediated by a decrease in calcium movement rather than a decrease in potassium movement into the intracellular space.
ON THE CONTRACTILE RESPONSE OF THE ISOLATED RAT UTERUS TO PROSTAGLANDIN E1
Authors: Paton D. M. , Daniel E. E.
Published: April 2011

The mechanism of action of prostaglandin E1 (PGE1) on rat uterine horns was analyzed. Contractile responses to PGE1 were not due to either release of known neurotransmitters or an interaction with their receptors. Responses could still be elicited in depolarized preparations. PGE1 contractions were Ca++-dependent; the drug appeared to require and utilize Ca++ from the superficial, loosely bound fraction. Anoxia markedly reduced responses to PGE1. Acetylcholine and PGE1 had the following properties in common: (a) neither was potentiated by elimination of external glucose or by lowering of the external K+ concentration, (b) both were still effective in depolarized horns, and (c) pretreatment with adrenaline or 2,4-dinitrophenol and iodoacetic acid reduced responses to both. It is concluded that PGE1 acts on a specific receptor. The receptor–drug interaction may or may not result in subsequent membrane depolarization. Contraction results from an action on the superficial loosely bound calcium fraction, and the processes leading up to this Ca++ release are markedly oxygen-dependent.
AMINO ACID EXCRETION PATTERNS IN DEVELOPING RATS
Authors: Webber William A.
Published: April 2011

Amino acid excretion patterns were studied in rats 2 to 12 weeks old. In general there was a decline in amino acid excretion over this period which paralleled that reported in human infants by other workers. The decrease was most marked for certain amino acids (glycine, histidine, and arginine). These changes in excretion are not explicable in terms of changes in plasma amino acid concentrations, nor is it likely that they result from differences in filtered load. They may reflect a progressive development of transport mechanisms for some amino acids over the period studied, in which case similar changes in the concentrating ability of rat kidney cortex slices would be predicted. Other possible explanations which are less readily tested include changes in permeability of the tubular cell membranes and differences in the glomerular filtering capacity relative to the amount of tubular tissue which has developed.
A MICROMETHOD FOR MEASUREMENT OF RENIN IN THE PLASMA AND KIDNEY OF RATS
Authors: Boucher R. , Ménard J. , Genest J.
Published: April 2011

A new micromethod for the measurement of renin activity and substrate in 0.1 ml of rat plasma and in 1 mg of rat renal tissue is described. In the procedure a rat substrate free of renin prepared from previously nephrectomized animals is used. Incubation is carried out in the presence of Dowex resin 50W-X2 (NH4+) for 12 hours, at pH 6.5, with an excess of rat substrate. Angiotensin formed during incubation is measured by a pressor assay in the rat. The reproducibility of the procedure was excellent. Recovery of angiotensin in amounts from 10 to 500 mμg was 77%. This method permits repeated measurements of renin activity in rats during acute experiments and in any physiological procedure. It can readily be adapted to other species.
CHANGES IN ADENOHYPOPHYSEAL CYTOLOGY AND NUCLEIC ACID CONTENT IN THE RAT 32 DAYS AFTER BILATERAL ADRENALECTOMY AND THE CHRONIC INJECTION OF CORTISOL
Authors: Kraicer Jacob , Herlant Marc , Duclos Pierre
Published: April 2011

Control, adrenalectomized, and cortisol-treated rats were maintained under rigidly controlled conditions, and the adenohypophyses were examined histologically with two staining procedures which differentiate six distinct cell types. Only one cell type demonstrated cytological evidence of increased synthetic activity 32 days after adrenalectomy (the changes were, however, minimal) and decreased synthetic activity following the chronic injection of cortisol. This cell type, which we designate as the corticotroph, would be classed as a chromophobe (no stainable granules) with use of standard histological techniques, but is, in fact, as Herlant's Tetrachrome demonstrates, a distinct acidophilic cell type different from the prolactin cell and the somatotroph. The determination of adenohypophyseal DNA and RNA revealed no evidence of increased protein synthetic activity following bilateral adrenalectomy, but did reveal evidence of decreased protein synthetic activity following the chronic injection of cortisol.
EFFECT OF SODIUM PYROPHOSPHATE ON EXPERIMENTAL SOFT-TISSUE CALCIFICATION AND HYPERCALCEMIA
Authors: Tuchweber B. , Gabbiani G.
Published: April 2011

Sodium pyrophosphate inhibited the cutaneous calcification induced by various metallic compounds in normal rats and in those treated with dihydrotachysterol (DHT). It also caused a. transient decrease in total serum calcium in normal rats and rats treated with calcium acetate, DHT, and parathyroid extract.
FACILITATION AND SPATIAL SUMMATION IN NEURONS CONCERNED WITH EPILEPTIFORM AFTERDISCHARGE IN THE ISOLATED CEREBRAL CORTEX OF THE CAT
Authors: Sanders H. D. , Pinsky C.
Published: April 2011

The relationships between epileptiform afterdischarges (EAD) and surface-positive burst responses recorded from neuronally isolated slabs of cerebral cortex were studied in 23 cats. The results suggest that a specific population of neurons participating in an EAD are facilitated by the afterdischarge activity. In their facilitated condition they can respond to weak electrical stimuli which had been ineffective previous to the EAD. The response of the activated neurons resembles the epileptiform bursts recorded toward the end of an afterdischarge; continued application of the weak stimuli at rates of from 0.5 to 2.0 per second can sustain the epileptiform activity for periods of up to 20 min. The initial epileptiform afterdischarge activity, and the sustained epileptiform bursts which can be evoked by the weak stimuli, are transmitted across an isolated cortical slab by a system of neurons which is distinct and separate from the neuronal networks which transmit the surface-positive burst response across the same slab.
A reappraisal of vascular effects of hexamethonium
Authors: Lewis J. A. , Deshmankar B. S.
Published: April 2011

The paper is a study of the contrasting effects of peripheral vasomotion on "ganglionic blockade" versus catecholamine depletion. Displacement plethysmography was reported on ambient temperature in 19 subjects, and digital flow at a constant temperature of 72° with similar clothing and in the horizontal position in 10 subjects. At the conclusion of the plethysmography a crude sweating test was applied to hand and foot in 10 cases. Ganglionic blockade with hexamethonium intravenously, independent of its blood pressure lowering effect, resulted in a slight to moderate decrease in the flow in the index finger and a moderate to significant increase in the flow in the great toe. Normal sweating of the hand and abolition of sweating in the foot was first incidentally observed by noting the moist hand and the warm dry foot during the course of preliminary studies and confirmed by sweating. Catecholamine depletion by guanethidine or bethanidine showed no change in the peripheral vasomotion unless the brachial blood pressure was lowered. It was then found that there was almost always an increased flow in both finger and toe, though usually greater in the toe than the finger. These observations suggest that there is a difference in response between the sympathetic ganglion supply to the upper extremity and that to the lower extremity, as reflected in both vasomotion and sweating.
Inhibition of thiourea-induced hemolysis by plasma
Authors: Walker Brian L.
Published: April 2011

The relative rates of hemolysis of rat erythrocytes in isotonic thiourea were determined using whole blood and washed cells. Washing the erythrocytes with isotonic saline increased the rate of hemolysis relative to that observed for cells in whole blood. The addition of plasma to the washed cells reduced the hemolysis rate again. These observations are believed to indicate the presence in the plasma of a component capable of protecting the erythrocyte against thiourea-induced hemolysis. Nutritional studies suggest a relationship between this component and dietary unsaturated fatty acids.
A microelectrophoresis method for heparin
Authors: Jaques L. B. , Balueux R. E. , Dietrich C. P. , Kavanagh L. W.
Published: April 2011

A microelectrophoresis procedure on agarose for heparin and related compounds and a simple electrophoretic chamber are described. The method permits simultaneous identification and measurement. Identification is made by migration of the sample relative to that of reference heparin. International Heparin Standard, a number of commercial heparins, and whale and dog heparin were found to have two components on microelectrophoresis. Leo heparin contained only one component and was used as the reference material Migration rates relative to Leo heparin were: hyaluronic acid, 0.70; chondroitin sulfate A/C, 0.87; chondroitin sulfate B, 0.866; heparinoid-G31150, 0.94; dextran sulfate, 1.06; International Standard heparin, 0.89–1.01; commercial heparins, 0.89–1.01; dog heparin, 0.90; whale heparin, 0.85. For quantitation, heparin is applied to the slide by micropipette and the optical density of the stained spot measured by densitometer. This is converted to international units from the curve obtained for optical density with varying amounts of International Heparin Standard. Microelectrophoretic equivalents (expressed in terms of international heparin units) were found to be, for Leo heparin, 0.99 units = 1.00 international unit; for commercial heparins, values were between 84 and 134 international units/mg. Heparin after injection can be demonstrated by this method in perfusion fluid, tissue, blood, and urine.
Quantitative determination of insulin output following an intravenous glucose tolerance test in the dog
Authors: Rappaport A. M. , Davidson J. K. , Kawamura T. , Lin B. J. , Zelin S. , Henderson J. , Haist R. E.
Published: April 2011

Nine dogs had 50 to 70% of their pancreas removed. The uncinate process with intact pancreatic branches of the inferior pancreaticoduodenal artery and vein was completely isolated. Blood was continuously collected from the superior pancreaticoduodenal vein, whose duodenal branches were clamped off as was also the inferior pancreaticoduodenal vein. The volume of blood collected was measured, timed, and analyzed for the concentration of plasma insulin activity by the mouse hemidiaphragm bioassay and by immunoassay. Mean fasting values were 11.4 ± 2.4 milliunits (bioassay) and 12.1 ± 3.8 milliunits (immunoassay) per kg body weight per h in native plasma respectively. The high amounts obtained by both methods are similar and match the daily insulin requirements per kilogram body weight of the depancreatized dog or man. Tolerance to glucose was decreased in four dogs because of their deprivation of endogenous insulin during the experiment. Insulin secretion rose in the first 5 min but showed a delayed greater peak around 1 h after the glucose injection. The total inflow of blood into the pancreatic remnant was determined with an electromagnetic flowmeter. After the injection of glucose the blood flow increased twofold, and corresponded in time to the peaks of insulin output. The outflow from the superior pancreaticoduodenal vein increased two to four times when its duodenal branch was unclamped, because of the increased inflow of intestinal blood. Five control dogs did not receive glucose. Their blood insulin levels did not rise. In these the pancreatic blood flow decreased gradually with a progressive loss of blood through continuous sampling, for 2 h.
Anorexigenic effects of adrenaline, amphetamine, and FMS 1A
Authors: Russek M. , Stevenson J. A. F. , Mogenson G. J.
Published: April 2011

Adrenaline 0.15 mg/kg, amphetamine 2 mg/kg, and urinary anorexigen (FMS 1A) 60 mg/kg, administered by intraperitoneal injection (i.p.), produced approximately the same average decrease in the food intake of rats fed for 1 h daily. Noradrenaline 0.15 mg/kg produced a much smaller decrease in food intake, and isotonic saline produced no significant change. Repetition of injections of adrenaline and amphetamine every second day revealed some variation of the anorexigenic effect, but no extinction of it was apparent during 10 injections. No conditioning of the anorexia to a saline injection was observed either. In rats fed ad libitum, only FMS 1A had a prolonged anorexigenic effect which was still apparent after 48 h. Adrenaline and amphetamine had only a small effect on the 24-h food consumption, but adrenaline injected just before the beginning of the dark period reduced by 90% the food consumption of the following hour although the intake for the next 23 h was approximately normal. This indicates that the immediate effect of adrenaline on the rats fed ad libitium was less in hungry than in recently fed rats.
The effect of intraperitoneal injections of hyperosmotic solutions on convulsions induced by drugs and hyperbaric oxygen
Authors: Wood J. D. , Watson W. J.
Published: April 2011

Intraperitoneal injections of gamma-aminobutyric acid (GABA), glucose, or urea (25 mmoles/kg) prior to exposure to hyperbaric oxygen all delayed the onset of convulsions, although there were large differences in the degree of protection. GABA was the most protective agent, and at lower dosage levels (10 mmoles/kg) was the only agent to delay appreciably the onset of convulsions. An anticonvulsant effect of both GABA and glucose was observed with thiosemicarbazide but not with picrotoxin or pentylenetetrazol. Brain dehydration did not appear to play an important role in the anticonvulsant action.