bluuebunny/crossref_metadata_2025 huggingface dataset:
Insulin biosynthesis: Effects of carbohydrates and related compounds
Authors: Lin B. J. , Haist R. E.
Published: April 2011

Incorporation of tritium-labeled leucine into proinsulin and insulin was used to indicate proinsulin synthesis and insulin formation. In these experiments the incorporation of labeled leucine into proinsulin and that into insulin were closely related. This incorporation was stimulated by addition of glucose and mannose but not by fructose. The glucose- and mannose-stimulated incorporation was inhibited by mannoheptulose. Inhibition by mannoheptulose was not relieved by addition of pyruvate. Pyruvate, with the addition of small amounts of fumarate and glutamate, failed to stimulate proinsulin and insulin synthesis even though insulin secretion was stimulated by tolbutamide or ribose. It was concluded that neither free glucose, nor pyruvate derived from glucose, acts as a signal to initiate biosynthesis. Possibly some more immediate metabolite of glucose or some enzyme or cofactor associated with its metabolism may be involved. Ribose and xylitol failed to stimulate the biosynthesis of proinsulin, and insulin. This, taken together with the reported stimulating effect of ribose and xylitol on insulin secretion, supports, for the islets, the postulate of Krass and LaBella for posterior pituitary hormones, that the pentose phosphate pathway is concerned with hormone storage and secretion rather than with hormone synthesis.
Oscillatory behavior of the sympathetic system induced by picrotoxin
Authors: Polosa Canio , Rosenberg Paul , Mannard Allan , Wolkove Norman , Wyszogrodski Issie
Published: April 2011

In cats anesthetized with sodium pentobarbital, paralyzed with gallamine, atropinized, and artificially ventilated, an intravenous injection of picrotoxin (dose between 2 and 5 mg/kg) consistently induced sustained oscillations of arterial blood pressure (BP). Because of their form, and regularity of repetition (range: 0.3 to 4 cycles/min), these oscillations can be considered analogous to vasomotor waves (Mayer waves), which are known to occur in conditions such as hemorrhage, metabolic acidosis, and cerebral ischemia. The BP oscillations characteristic of picrotoxin intoxication have the following properties: (i) they are generated in the CNS since they are abolished by ventral root block; (ii) they are accompanied in most cases by oscillations of the nictitating membrane tension of the same frequency; and (iii) they occur in animals with complete transection of the spinal cord at a cervical level and in those with sectioned ninth and tenth nerves; hence they are not dependent upon afferent impulse traffic arising in baro- and chemo-receptors. Furthermore, nictitating membrane tension oscillation has been seen when BP was maintained stable. The latter observations indicate that for maintaining the oscillation in the sympathetic system the concomitant hemodynamic changes are not essential. It would appear that the oscillation is the result of epileptiform activity of sympathetic neurons. Perhaps some types of spontaneously occurring vasomotor waves have a similar origin.
Effects of Mn++ on 45Ca content and potassium-induced contraction of the aortic strip
Authors: Shibata Shoji
Published: April 2011

Pretreatment with Mn++ at 5 and 1 mM for 30 min prevented the increased 45Ca uptake of rabbit aortic strip observed during the potassium-induced contraction (40 mM) without significantly reducing the magnitude of the contraction and decreased 45Ca content of unstimulated muscle. Addition of Mn++ was found to restore the contractile response to potassium after this had been lost in Ca-free media.
In vitro ACTH assay: Influence of strain on responsiveness of rat adrenals
Authors: Kraicer J. , Morris A. , Gosbee J. L. , Conrad R. G. , Brown R. J.
Published: April 2011

We compared adrenals from rats obtained from six suppliers in the in vitro ACTH assay. The slope of the response of one strain (Canadian Breeding Laboratories, Sprague–Dawley) was consistently greater and the adrenals were consistently more sensitive than those from the other strains tested.
The role of insulin in the synthesis of fetal glycogen
Authors: Manns J. G. , Brockman R. P.
Published: April 2011

Experiments were performed on 21-day-old rat fetuses to determine the effect of insulin or insulin antibodies on the incorporation of 14C-glucose into liver and muscle glycogen. Radioactive glucose was infused for 4 h into the maternal circulation; experiments were done on unanesthetized animals. Fetuses injected with insulin incorporated more 14C-glucose into liver glycogen than littermate controls; fetuses injected with insulin antibody incorporated less than their controls. The results suggest that insulin has a regulatory effect on the synthesis of fetal liver glycogen.
Effects of dopamine on the liver before and following administration of endotoxin
Authors: Shanbour Linda L. , Hinshaw Lerner B.
Published: April 2011

These studies were conducted to determine the effects of dopamine on the canine liver before and following endotoxin administration. Isolated, denervated livers were perfused via arterial and venous inflow vessels at constant rates by donor dogs. Weights were continuously recorded throughout the experiments. There were marked reductions in liver weight with dopamine infusion before endotoxin administration and continued reductions at slower rates following endotoxin. The mechanism of liver shrinkage is postulated to be primarily due to sinusoidal contractions independent of changes in liver venous resistances. Dopamine markedly increased hepatic artery pressures; thus hepatic artery resistances increased since the flows were constant. In the donor animal, dopamine elevated systemic arterial pressure, pulse pressure, and heart rates.
Effect of high- and low-bulk diets on the thyroxine turnover rate in rats with acute and chronic exposure to different temperatures
Authors: Héroux O. , Petrovic V. M.
Published: April 2011

Thyroid activity was estimated from thyroxine (T4) turnover rate values by using the single injection isotope dilution technique in rats acclimated to 28 °C and 6 °C and fed either a high-bulk diet (Master Laboratory Cubes (MLC)) or a low-bulk thyroxine-free diet (T4F). In cold-acclimated rats, whether fed MLC or T4F, the metabolic clearance rate of thyroxine was faster than in the 28 °C control rats. The plasma thyroxine level was unchanged after cold acclimation in rats fed MLC but was significantly lower in the T4F-fed rats. The product of the metabolic clearance rate and the plasma thyroxine level or the thyroxine turnover rate was significantly higher after cold acclimation in rats fed the commercial chow diet (MLC) than in rats fed the semipurified T4F diet. This result demonstrates that the increased thyroxine turnover rate, previously observed in cold-acclimated rats, can be taken as another example of a diet-dependent change similar to the thyroid hypertrophy, higher resting metabolic rate, and greater fecal excretion of thyroxine, which have all been shown to be diet-dependent and unnecessary once cold acclimation is established.
Transmembrane potential and force of contraction of the normal and potassium-deficient human atrial tissue in vitro
Authors: Prasad Kailash
Published: April 2011

The characteristics of the simultaneously recorded action potential (AP) and contraction of isolated atrial tissue of human heart were studied in normal and in potassium-free solutions. Two types of action potentials associated with characteristic contractions were observed. Pacemaker types of action potentials with two humps in the plateau were observed in spontaneously beating atria and they were associated with triple contractions. A non-pacemaker type of action potential was found in quiescent fibers when the preparation was driven electrically; this resulted in single peak contraction. The sizes of the resting and action potentials of pacemaker cells were lower, while those of action potential duration in all types of cells were higher than those reported in other mammals. When spontaneously beating atrial pieces were exposed to a potassium-free solution there was a shortening of the action potential plateau and lengthening of the terminal phase of repolarization associated with the development of the first hump into a slow spike. The shortening of the action potential plateau associated with an increase in the force of contraction was also observed in electrically stimulated muscles in KCl-free solution.
Exercise tolerance of cold-acclimated rats: Serum and liver enzymes and histological changes
Authors: Dieter M. P. , Altland P. D. , Highman B.
Published: April 2011

Cold-acclimated rats were able to tolerate 5 h exercise, but one-third of them died during 9 h exercise. Neither period of exercise resulted in the death of unacclimatized animals. The parameters measured after 5 h exercise revealed no substantial differences between the unacclimated and cold-acclimated groups. Nine hours exercise resulted in significantly greater elevations in serum glutamic pyruvic transaminase, lactic dehydrogenase, and malic dehydrogenase in cold-acclimated rats. Except for serum glutamic pyruvic transaminase, the activities returned to control levels within 2 days. The tissue enzyme changes after 9 h exercise of cold-acclimated rats were generally less than in unacclimated rats. Liver lactic dehydrogenase and α-glycerophosphate dehydrogenase activity in unacclimated rats rose significantly above that of cold-acclimated rats 2–3 days after exercise. The decreases in hepatic glycogen and blood glucose after exercise were greater in cold-acclimated rats, and restoration of blood glucose levels occurred more slowly. These biochemical changes were not correlated with a greater rise in plasma corticosterone or a higher incidence of fatty visceral changes or muscle necrosis in cold-acclimated rats. In general, the homeostatic mechanisms available to singularly stressed rats appear to be exhausted in dually stressed ones. The loss of tissue enzymes to the serum and failure of tissue enzymes to respond to exercise stimulation undoubtedly contributed to the reduced exercise tolerance of cold-acclimated rats.
Evaporative cooling in the rat: Effects of hypothalamic lesions and chorda tympani damage
Authors: Stricker Edward M. , Hainsworth F. Reed
Published: April 2011

Previous studies have demonstrated the importance of saliva spreading for evaporative cooling by rats in the heat. In particular, submaxillary–sublingual salivary gland function must be unimpaired for the rat to regulate its body temperature at ambient temperatures above 38 °C. The present study investigated some of the neural components of this thermoregulatory effector system. Bilateral destruction of the chorda tympani, the parasympathetic innervation of the submaxillary–sublingual glands, severely impaired the rat's tolerance of high ambient temperatures. Rats with bilateral electrolytic lesions in the anterior or lateral hypothalamus, placed without chorda tympani damage, also showed pronounced deficits in salivary evaporative water loss and impaired thermal tolerances during heat stress. Other heat loss mechanisms, such as peripheral vasodilatation, may also have been disrupted. These results support previous reports of thermoregulatory deficits in rats following hypothalamic lesions.
Evaporative cooling in the rat: Effects of dehydration
Authors: Stricker Edward M. , Hainsworth F. Reed
Published: April 2011

Previous investigations demonstrated that the water loss of rats associated with increased salivary evaporation during heat stress is derived from both intracellular and intravascular sources. The present studies indicate that sufficient dehydration of either fluid compartment will impair temperature regulation. Salivary excretion from all dehydrated rats was virtually abolished at ambient temperatures below 38–40 °C, but temperature regulation was still possible if a large temperature gradient existed between the animals and the environment. Above these ambient temperatures, where increased evaporation is essential to survival, the rate of evaporative water loss returned to normal. However, body water reservoirs in dehydrated rats were rapidly depleted, salivary evaporation could not be maintained, and survival times were shortened. In contrast, access to drinking water significantly increased thermal tolerance. These results emphasize the importance of adequate body fluid hydration for evaporative cooling through saliva spreading by rats in the heat. In addition, they indicate that allocation of body water for evaporation takes precedence over conflicting demands for water conservation during heat stress.
Studies with fluorescein-conjugated antisera to growth hormones. III. Localization and inhibition studies with antisera to porcine growth hormone
Authors: Nayak R. , McGarry Eleanor E. , Beck J. C.
Published: April 2011

Fluorescein-conjugated antisera to porcine growth hormone localize in acidophils of rat, pig, beef, sheep, and dog pituitaries. Using AT – PAS – orange G stain, two types of acidophils could be distinguished in pig, beef, sheep, and dog pituitaries. Localization of anti-porcine growth hormone was confined to only one acidophil cell type in pituitaries of these species.
Metabolic interrelations of glucose and lactate in unanesthetized normal and diabetic dogs
Authors: Forbath N. , Hetenyi Jr. G.
Published: April 2011

Uniformly labelled 14C-glucose infusions were given to normal and pancreatectomized dogs. Plasma glucose and lactate specific activities were measured by appropriate methods. In normal dogs 14–28% of plasma lactate was found to originate from circulating glucose, and in diabetic dogs 11–18%. This fraction was markedly increased in normal but not significantly so in diabetic dogs during a 2-h infusion of a 6.7–11 mg/kg min glucose load. Uniformly labelled 14C-L(+)-lactate and glucose-6-3H were infused simultaneously for 5 h in normal and pancreatectomized dogs. The glucose turnover rate and incorporation of lactate carbon into glucose were calculated. Of the utilized lactate carbon, 41–49% was incorporated into plasma glucose. The recycling rate of glucose carbon via lactate was estimated to be 3–8% of the glucose turnover rate in the normal dog in the postabsorptive state. The absolute rate of gluconeogenesis from lactate was found to be increased in diabetes.
The effect of bilateral nephrectomy on the production and distribution of muramidase (lysozyme) in the rat
Authors: Keeler R.
Published: April 2011

After bilateral nephrectomy total body muramidase in the rat increased by more than 50%. The mean rate of increase was 340 μg/h per 100 g. Skin and bone showed the greatest increase. Although the lungs contain a high level of muramidase there was no significant change in the level of enzyme activity after nephrectomy. Rats with sectioned ureters or with a uretero–venous anastomosis did not develop high plasma levels of muramidase. The response to nephrectomy is therefore not a response to uremia. Pretreatment of the animals with cortisone or DL-ethionine had no effect on the enzyme response to nephrectomy. This was taken to indicate that the response was not to antigenic material and did not depend upon hepatic synthesis of the enzyme. Pretreatment with the cytotoxic agent cyclophosphamide reduced the plasma and total body level of muramidase and blocked the response to nephrectomy. Direct measurement demonstrated a large increase in the rate of muramidase production by bone marrow. Since the in vitro inactivation of muramidase by kidney tissue could not be demonstrated, it is concluded that nephrectomy causes an increase in the rate of enzyme production rather than a failure of catabolism. Renal tissue might normally exert an inhibitory influence upon muramidase formation.
Cardiac output: Rapid estimation from indicator dilution curves using a new Nomogram
Authors: Olley P. M. , Kidd B. S. L. , Zelin S.
Published: April 2011

Estimation of the cardiac output from dye dilution curves using Hamilton's method is time consuming when many curves require analysis. We have designed a Nomogram based on the treatment of the dilution curve as a series of three parabolas followed by an exponential decay. The results obtained from this Nomogram have been compared with those obtained by Hamilton's method and given a correlation coefficient of 0.998.
The effect of destruction of the bundle of His or the atrioventricular node on cyclopropane–adrenaline cardiac arrhythmias
Authors: Sasyniuk Betty I. , Dresel Peter E.
Published: April 2011

Destruction of the bundle of His abolished bigeminal rhythms produced by adrenaline in thiopentone–cyclopropane anesthetized dogs. Bigeminal rhythms were still elicited, however, after selective destruction of the A–V node. Destruction of the bundle of His did not prevent multifocal arrhythmias but did increase the dose of adrenaline required to induce them. Multifocal arrhythmias produced after destruction of the bundle of His were abolished by injections of acetylcholine into the left anterior descending, but not the circumflex coronary artery, results opposite to those obtained in normal hearts.
Seasonal observations on the plasma, red cell, and blood volumes of two turtle species native to Ontario
Authors: Semple Robert E. , Sigsworth Dale , Stitt John T.
Published: April 2011

Two turtle species, Graptemys geographica and Chelydra serpentina were studied. The animals were obtained in the Kingston, Ontario area and maintained in the lake from which most of them had been taken. T-1824 and 51Cr were used to determine plasma and erythrocyte volumes respectively. In vitro and in vivo tests established that these methods were satisfactory, but mixing times in these poikilotherms were longer than mixing times in mammals. In G. geographica, plasma volume showed seasonal variations. The mean plasma volume in winter was 77.8 ml/kg, a volume significantly lower than the summer mean of 106.7 ml/kg. There was no significant seasonal variation in red cell volume; the mean for all seasons was 18.1 ml/kg. In this species lower plasma volumes resulted in significantly lower blood volumes during the winter. Evidence is presented in support of the concept that in G. geographica, in winter, an appreciable volume of plasma is sequestered and not available to the general circulation. In C. serpentina plasma volume was significantly lower than in the other species but there were no significant seasonal variations. For all seasons mean plasma volume was 65.7 ml/kg and mean erythrocyte volume was 18.5 ml/kg.
Data on serum tocopherol levels in a selected group of Canadians
Authors: Hoppner K. , Phillips W. E. J. , Murray T. K. , Campbell J. S.
Published: April 2011

A survey of serum tocopherol levels of 125 subjects, staff and patients, at an Ottawa hospital was conducted. The mean serum tocopherol level for all subjects was 1.29 ± 0.34 mg/100 ml with a range of 0.70 to 2.5 mg/100 ml. No significant differences were observed between mean serum tocopherol levels of patients and staff members, smokers and nonsmokers, and men and women. Serum tocopherol levels of subjects 25 years old and younger were significantly lower than those over 25 years of age. No values were found in the deficiency range below 0.5 mg/100 ml.
Renin inactivation by human plasma
Authors: Regoli D.
Published: April 2011

To study the inactivation of renin by human plasma, human angiotensinogen was partially purified by the method of Haas et al. (1966) and human renin was separated from angiotensinases by passing the kidney extract through a carboxymethyl cellulose column (CMC). Partially purified human angiotensinogen is almost free of angiotensinase activity when used in diluted solutions and for short periods of incubation. In concentrated solution, a residual angiotensinase activity is observed, which belongs probably to angiotensinase B. CMC chromatography of kidney extracts separates renin from angiotensinases and gives a recovery higher than 50% for renin. The renin obtained with this method is stable at 0° for 24 h, while when incubated in the presence of human plasma at 37 °C for 2 or 4 h, its activity decreases significantly. The renin-inactivating factor present in human plasma destroys rat renin, while it does not modify the activity of hog renin. The renin inactivation is prevented when plasma is treated with EDTA (20 mM) or acidified at pH 3.0 for 30 min before incubation. The renin inactivating system, present in human plasma, is different from renal angiotensinases and may be an enzyme.
Biophysical analysis of the mechanical properties of the sarcolemma
Authors: Fields R. Wayne , Faber J. Job
Published: April 2011

This paper attempts to explain the complex mechanical properties of the sarcolemma of single muscle fibers. Previously published measurements on retraction zones of frog semitendinosus fibers were used as a basis for computation. A somewhat slack system of helical fibers in the sarcolemma can adequately account for the observations. It explains the shape of the tension–elongation curves of sarcolemma and its anisotropy. It permits the drastic transfiguration from normal shape to retraction zone shape in the absence of undue stresses. The angle of the helices was calculated to be 55° in the muscle fiber at rest length. This is also the angle permitting maximal volume of the muscle fiber. The Young's modulus of the fiber system was calculated to be in approximate agreement with the modulus published for collagen. With the single additional assumption that muscle fiber volume has a certain value within the range permitted by the measurements, the helical system can be shown to limit muscle fiber length between 70% and 140% of its rest length. The proposed helical fiber system is thus found to have properties that make it a likely candidate for the parallel elastic element of muscle.
Studies on the mechanism of experimental congestive heart failure in dogs
Authors: Belleau L. , Mion H. , Simard S. , Granger P. , Bertranou E. , Nowaczynski W. , Boucher R. , Genest J.
Published: April 2011

Congestive heart failure was produced in nine dogs following surgical removal of the tricuspid valve. Six dogs developed ascites with or without peripheral edema, and four dogs remained ascites-free for 5, 6, and 11 weeks (one dog in this latter group did later develop ascites 14 weeks following operation; it was therefore studied twice and included in both groups). Systolic aortic pressure, sodium balance, right atrial pressure, glomerular filtration rate, sodium para-aminohippurate clearance, plasma aldosterone, norepinephrine, renin activity, and antidiuretic hormone levels were measured in each dog before surgery and during the experimental period of the steady state of edema in the dogs of group A, and at 5, 6, and 11 weeks in the four dogs of group B. Right atrial pressure increased considerably and glomerular filtration rate and sodium para-aminohippurate clearance decreased markedly in each dog. The most significant and important findings were (1) normal sodium balance in the dogs of group B without ascites, whereas four of the six dogs with ascites had a markedly positive sodium balance; (2) increased antidiuretic hormone activity levels in all dogs with congestive heart failure and ascites in contrast with the absence of any change in the dogs without ascites. The changes in plasma aldosterone, norepinephrine, and renin activity levels were not consistent. It is suggested that the antidiuretic hormone may play a role in the formation of ascites and edema in dogs with congestive heart failure following total removal of the tricuspid valve.
A method for determination of renin activity in dog's plasma and renal tissue
Authors: Granger P. , Boucher R. , Genest J.
Published: April 2011

A procedure based on that of Boucher et al. (Can. J. Physiol. Pharmacol. 45, 881 (1967)) for the microdetermination of plasma renin activity in the rat is described for the measurement of the same parameter in 1 ml of dog plasma. This procedure permits serial determinations and uses homologous substrate with incubation with Dowex 50W-X2 (NH4+) at pH 5.5 for 12 h. The results are expressed as nanograms of angiotensin formed per milliliter of plasma after 12 h of incubation. The mean plasma renin activity in healthy dogs was 1.04 ng/ml per h, ± 1.03 S.D., with a range of 0–3.3 ng. This procedure was applied to the measurement of renin activity in renal tissue.
Renin activity and norepinephrine, cation, and water contents of cardiovascular tissue of dogs with congestive heart failure and ascites
Authors: Hayduk K. , Brecht H. M. , Vladutiu A. , Simard S. , Rojo-Ortega J. M. , Belleau L. , Boucher R. , Genest J.
Published: April 2011

Six dogs with congestive heart failure and ascites were studied for (a) renin, norepinephrine, water, sodium, potassium, calcium, and magnesium contents in cardiovascular tissues; (b) plasma renin activity and renin substrate; (c) renal renin activity, juxtaglomerular index, and glucose-6-phosphate dehydrogenase activity in macula densa cells, and α-glycero-6-phosphate dehydrogenase activity in macula densa cells and juxtaglomerular bodies. The most important findings were: (a) a significant decrease in renal renin activity and in the juxtaglomerular index coinciding with increased activities of glucose-6-phosphate and α-glycero-6-phosphate dehydrogenases in macula densa cells when compared with normal renal tissue; (b) a highly significant increase in norepinephrine content in branches of mesenteric veins combined with a decrease in norepinephrine content in most arteries studied; (c) a significant increase in the sodium content of most arteries studied, without any change in water content.
Extrahepatic factors in the early hypotensive response to bacterial endotoxin
Authors: Blattberg Benjamin , Levy Matthew N.
Published: April 2011

Experiments were designed to determine the relative importance of hepatic and extrahepatic factors in the arterial hypotension observed shortly after the injection of bacterial endotoxin. In one series of experiments, the increase in portal venous pressure, ordinarily evoked by endotoxin, was markedly attenuated by means of a servo-controlled pump. Despite the absence of an appreciable rise in portal venous pressure, arterial pressure progressively fell 50 mm Hg, below the control level, during the first 30 min after endotoxin. In a second series of experiments, a comparison was made between dogs in which the hepatic circulation was either bypassed or included in the circulation. With the liver excluded, arterial pressure declined 40 mm Hg, below control, in the first 15 min after endotoxin. The fall in arterial pressure in both series is believed to be attributable to venous pooling in regions other than the hepatoportal vascular bed.
Effect of feeding cod liver oil on the fate of radiotocopherol in sheep
Authors: Hidiroglou M. , Jenkins K. J. , Lessard J. R. , Borowsky E.
Published: April 2011

The metabolism of a single dose of 3H-DL-α-tocopherol was studied in 16 sheep fed a dystrophy-producing hay alone or supplemented with cod liver oil. During the experimental period, which lasted for 5 days after the radioisotope dosing, radioactivity was higher in the rumen liquor of cod liver oil fed sheep than in those which received only hay. Significantly lower levels of radioactivity were found in the non-saponifiable material of various tissues of cod liver oil fed sheep than in the corresponding tissues of the unsupplemented animals. By means of column chromatography, thin layer chromatography, and radioautography the bulk of liver radioactivity was identified as unchanged α-tocopherol. Possible reasons for the difference in tissue radioactivity levels between cod liver oil fed and unsupplemented sheep are discussed.
Determination of pancreatic amylase activity by a radial diffusion assay
Authors: Bélanger André , Perreault Jean , Couture Yvon , Dunnigan Jacques
Published: April 2011

A technique for assay of amylase content in homogenates of rat pancreas is described. It is based on the measurement of the diameter of a "reaction zone" resulting from the action of the enzyme diffusing through a gel containing the substrate. The method is used to evaluate the amylase content of the pancreas of rats stimulated by feeding and by insulin-hypoglycemia. The results are compared with those obtained by a classic amyloclastic method, using the optical density of the starch-iodine complex.
Dissociation of the downhill calcium movements from sodium and potassium movements in rat uterus
Authors: Batra S. C. , Daniel E. E.
Published: April 2011

The effects of iodoacetic acid (IAA), IAA and 2,4-dinitrophenol (DNP), and ethacrynic acid (ETCA) (each 10−3 M) on Na, K, Ca, and water movements in rat uterus were studied. All these compounds caused tissues to gain Na, Ca, and water and lose K. The ratio of K loss to Na gain was much lower with ETCA as compared with IAA or IAA and DNP. Net Ca movements showed a definite lag compared with those of Na and K in every case. The gain in tissue water after IAA or IAA and DNP was greater than that after ETCA, which also occurred much later. The loss of K except with ETCA was initially greater than the Na and Ca gained in exchange for it. Subsequently in IAA or IAA and DNP the Na and Ca gained, unaccompanied by bathing solution, was in excess of K loss, as it was from the beginning with ETCA. These results suggested a different metabolic dependence and (or) a different transport mechanism controlling Ca distribution from that controlling Na and K distribution. Furthermore, the mechanism controlling H2O distribution seems to be partially independent of net sodium gain. The data also suggest that binding and unbinding of cations may be involved in controlling ion distribution in the rat uterus.
Effect of metabolic inhibition on the cation binding and exchange in the rat uterus
Authors: Batra S. C. , Daniel E. E.
Published: April 2011

The metabolic inhibitor iodoacetate (IAA) at a concentration of 10−3 M caused Na and Ca gain and K and Mg loss from rat uteri. Ethacrynic acid (ETCA) also at 10−3 M has similar effects except on Mg. The residual cation contents (bound cation) of the washed particulates from homogenized normal or inhibited rat uteri were similar. Both types of particulates contained a larger proportion of tissue Ca and Mg than of tissue Na or K. Particulate material from IAA-inhibited tissues bound less K and more Ca than controls and exchanged more K for Na than controls. In unwashed particulate material there was more Na and Ca and less K and Mg in IAA-treated compared with similar material from controls. Though they were in the right direction the above differences did not account for the altered ion contents of metabolically inhibited intact cells. Our studies of passive ion binding did reveal at least three types of binding sites: those from which cations could be removed by washing, those from which they could be removed by ion exchange (Na, K, Ca, or Mg) or EDTA (Ca and Mg), and those from which they could not be removed by either of these procedures.
Tissue-level bone formation rates in chronic renal failure, measured by means of tetracycline bone labeling
Authors: Hitt O. , Jaworski Z. F. , Shimizu A. G. , Frost H. M.
Published: April 2011

In 16 patients entering a renal dialysis program and given tetracycline bone labels prior to 11th rib biopsy, tissue-level bone formation rates measured by quantitive histological analysis fell below normal in each case and on both the haversian and cortical–endosteal bone surfaces, averaging one-third of normal. On both envelopes there were increases in the relative and absolute amounts of osteoid seam perimeter in a unit amount of bone as well as in the total volume of osteoid in a unit amount of bone.
Correlation between the activity of liver enzymes and the LD50 of parathion in the rat
Authors: Alary J.-G. , Brodeur J.
Published: April 2011

A study was undertaken to investigate a possible correlation between the acute LD50 of parathion, in weanling and adult male and female rats, and the activity of the liver enzymes involved in the in vitro metabolism of parathion and its toxic oxygen analogue, paraoxon. A close relationship was found in adult male and female rats, as well as in adult females pretreated with phenobarbital, between the LD50 and the rate of in vitro degradation of parathion by the liver under experimental conditions in which both oxidative and hydrolytic metabolism occur. On the same basis, immature rats appeared to be more sensitive to parathion than was to be expected from the ability of their livers to metabolize parathion in vitro. It is concluded that the rate of in vitro degradation of parathion by the liver is a satisfactory index of the in vivo toxicity of parathion in adult rats, but not in immature animals.
The Effect of Nicotinic Acid, 5-Methylpyrazole-3-carboxylic Acid (U-19425), and Dibutyryl Cyclic AMP on Renal Gluconeogenesis
Authors: Issekutz Andrew
Published: April 2011

The effects of nicotinic acid, 5-methylpyrazole-3-carboxylic acid (U-19425), and dibutyryl (DB-) cyclic AMP on gluconeogenesis from lactate, oxalacetate, and glycerol were studied in kidney cortex slices. DB-cyclic AMP stimulated glucose formation from lactate (+67%), but not from oxalacetate or glycerol. Nicotinic acid and U-19425 inhibited gluconeogenesis from all three substrates by 30–63%. DB-cyclic AMP stimulated gluconeogenesis from lactate in the presence of either inhibitor. DB-cyclic AMP abolished the inhibition by either drug on glucose formation from oxalacetate or glycerol. It is concluded that nicotinic acid and U-19425 may inhibit gluconeogenesis by decreasing the cyclic AMP level within the cells, and that a minimal concentration of cyclic AMP may be functional above the triose phosphate level.
Maintenance of the Ionic Composition of the Incubated Artery
Authors: Palatý Vladimír , Gustafson Brigid K. , Friedman Sydney M.
Published: April 2011

The ionic composition of the incubated rat tail artery, comparable but not identical to that of the freshly dissected tissue, can be maintained over a period of at least 5 h under aerobic conditions in the absence of utilizable exogenous substrate. A sufficient supply of exogenous glucose must be provided for the maintenance of this ionic composition under anaerobic conditions. The changes in the content of individual ions and water brought about by iodoacetate poisoning can be prevented more or less completely by addition of a utilizable noncarbohydrate substrate such as pyruvate or butyrate to the incubation medium. Abolition of the transmembrane ionic gradients caused by 2,4-dinitrophenol or oligomycin can be partially-prevented by exogenous glucose. The ionic composition of the artery is little affected by fluoroacetate inhibition even in the absence of utilizable exogenous substrate. The content of magnesium is decreased by 2-deoxy-D-glucose, although the content of other ions remains unchanged. Metabolic energy seems to be required to prevent the tissue calcium from rising.
Effect of Splenectomy on the Activity of Drug-Metabolizing Enzymes in the Liver of Rats
Authors: Brodeur Jules , Marchand Claude
Published: April 2011

Splenectomy was performed in adult female rats in order to investigate the influence of removal of the spleen on liver microsomal enzymes and cytochrome P-450 in vitro, as well as on the pharmacological activity of certain drugs in intact animals. Splenectomy significantly decreases the amount of cytochrome P-450 at 1 and 4 days after the operation, but not at 7 days. The activity of the enzymes catalyzing the metabolism of parathion, p-nitroanisole, and zoxazolamine is also decreased 4 days after splenectomy, whereas that of the enzymes involved in the metabolism of hexobarbital is unchanged. The maximal induction by phenobarbital of the enzymatic activities catalyzing the metabolism of parathion, p-nitroanisole, and zoxazolamine is prevented by splenectomy. Splenectomy exerts very little effect on plasma levels of hexobarbital and hexobarbital sleeping time; however, in both control and phenobarbital-pretreated rats, splenectomy results in a marked increase in the duration of zoxazolamine paralysis. These results indicate that splenectomy exerts inhibitory effects on certain liver microsomal enzymes, and provide some indirect evidence in support of the view that the hepatic blood supply is important for maintaining normal levels of drug-metabolizing enzyme activity in the liver.
The Influence of Muscular Work on the Capillary Density in the Heart and Skeletal Muscle of Pigeon (Columbia livia dom.)
Authors: Rakušan K. , Ošt'ádal B. , Wachtlová M.
Published: April 2011

Pigeons flying for 1 year were compared with their nonflying littermates. The physically active animals proved to have higher weights of the heart and breast muscle. In both tissues, a significantly higher water content was found in animals with restricted activity.The heart and breast muscle of the pigeon are characterized by high capillary counts (over 4000 capillaries/mm2 in the heart muscle and over 2000 capillaries/mm2 in the breast muscle). The capillary density in the heart muscle was the same in both groups, while the capillary density in the breast muscle was significantly lower in the physically active animals.
Biochemical Basis of Heart Function. III. Influence of Isoproterenol on the Norepinephrine Stores in the Rat Heart
Authors: Dhalla Naranjan S. , Balasubramanian V. , Goldman Jack
Published: April 2011

A single subcutaneous injection of isoproterenol into rats markedly reduced the concentration of norepinephrine (NE) in their hearts, but doses greater than 20 mg/kg failed to decrease NE levels below 30–40% of the control value. Restoration of lost NE began more than 48 h after injection of the isoproterenol and was not complete in 96 h. Twenty-four hours after treatment with isoproterenol the pattern of subcellular distribution of the NE in the heart was not altered from the controls, but 96 h after treatment the NE concentration had decreased in the granular fraction and increased in the soluble fraction. Isoproterenol failed to decrease NE levels in other adrenergically innervated organs such as spleen and brain. Subcutaneous doses (1 mg/kg) of NE and epinephrine also reduced the cardiac NE in the control animals but did not further reduce the NE stores in the hearts of isoproterenol-treated rats. A second injection of isoproterenol (20 mg/kg) also failed to further decrease the NE stores in the hearts of isoproterenol-treated animals. On the other hand, tyramine treatment or exposure of the rats to cold (4 °C) for 4 h lowered the cardiac endogenous NE in both the control and isoproterenol-treated animals. Pretreatment of rats with TM-10, tranylcypromine, dibenamine, and propranolol failed to prevent the isoproterenol-induced decrease in cardiac NE stores. The data reveal that isoproterenol-resistant norepinephrine stores in the heart are susceptible to the action of tyramine or cold exposure, and the isoproterenol-induced alteration in catecholamine stores may not be the result of a direct action of this agent on the adrenergic nerve terminal.
Transmembrane K+ and Cl− Activity Gradients for the Muscle Fiber of the Giant Barnacle
Authors: Hinke J. A. M. , Gayton D. C.
Published: April 2011

The activities of K+ and Cl− in the myoplasm of single fibers from the giant barnacle were measured at differing steady states by means of ion-selective microelectrodes. In one experiment, the fiber was equilibrated in a series of solutions in which [K]o and [Cl]o varied but [K]o × [Cl]o and [K]o + [Na]o were constant. In a second experiment, the fiber was equilibrated in solutions in which [K]o varied but [Cl]o and [K]o + [Na]o were constant. In a final experiment, the fiber was equilibrated in solutions in which [K]o, [Cl]o, and osmolarity were increased. The results support the view that the free K+ and Cl− activities in the myoplasm of the muscle fiber in the steady state can be defined by the equation (aK)o/(aK)i = (aCl)i/(aCl)o = exp (EF/RT), where a refers to ionic activity and E to the membrane potential. (Subscripts o and i refer to 'outside' and 'inside' the fiber, respectively.) The results are consistent with the results presented in the following paper which indicate that a significant fraction of the intracellular Cl− is not free in the myoplasm and that free myoplasmic Cl− is excluded from about 45% of the intracellular water. Free myoplasmic K+ appears to be excluded from only 15% of the intracellular water. The results also demonstrate that, because of the ion and water heterogeneity in the fiber, fiber concentrations of K+ and Cl− cannot be used in place of activities in the above equation.
Correlation between the Electrical Activity and Acetylcholine Release from the Cerebral Cortex and Medulla during Hypercapnia
Authors: Metz Bernard
Published: April 2011

Studies were undertaken to determine whether any correlation exists between the level of acetylcholine (ACh) release from the cerebral cortex and medulla and the electrical activity within those same brain areas during hypercapnia, hypoxia, and hypoxia plus hypercapnia in combination. The cerebral cortex and medulla of anesthetized dogs released ACh spontaneously through push–pull cannulae after perfusion with an anticholinesterase, sarin. Hypercapnia (12% CO2) evoked an increased release of ACh above the basic spontaneous level from the cerebral cortex and medulla, with a parallel rise in the integrated electrical activity as monitored by EEG recordings. Hypoxia plus hypercapnia (8% O2 + 12% CO2) induced an ACh release comparable with hypercapnia alone, but with no change in the electrical activity. Hypoxia (8% O2) produced no increase in ACh release or electrical activity. Areas in the medullary reticular formation responsive to injections of CO2-buffered bicarbonate solutions ("respiratory responsive areas") produced during hypercapnia an augmented release of ACh, paralleled by a concomitant rise in the electrical activity, both of which were of greater magnitude than that manifested in either the "nonrespiratory responsive areas" of the medulla or in the cerebral cortex. The data suggest that a correlation exists between the ACh release and the electrical activity during hypercapnia. Thus, cholinergic neurons in the cerebral cortex and medulla may be activated during hypercapnia and are possibly involved in the medullary regulation of respiration. Furthermore, the evidence supports the concept that the pathways involved in EEG activation and ACh release are distinct.
The Effect of Added External Resistance on Regional Pulmonary Filling and Emptying Sequences
Authors: Martin R. R. , Wilson J. E. , Ross W. R. D. , Anthonisen N. R.
Published: April 2011

Using the radioactive 133Xe technique, the effects of external resistances on the distribution of inspired gas and on the expiratory alveolar plateau were examined in four normal subjects. Subjects inhaled 133Xe boli one of three ways: slowly through minimum external resistance, with maximum speed through minimal resistance, and with maximal effort but at very low flow rates through a large external resistance. Also, always after a slow inspiration through low resistance, subjects expired in three different ways: slowly through minimal resistance, with maximum speed through minimal resistance, and finally with maximal effort through an external resistance which sharply limited flow rates. Both regional intrapulmonary 133Xe distribution and the shape of the alveolar plateau appeared to depend entirely on flow rate and to be independent of effort. These results were interpreted as indicating that variations in respiratory effort do not produce variations in dynamic pleural pressure between lung regions.
Effect of Aniline on Plasma Corticosterone in Rats
Authors: Toth S. , Yeghiayan E. , Kovacs K.
Published: April 2011

In rats, aniline lowers the plasma corticosterone level and causes adrenocortical enlargement. The responsiveness of the adrenals to insulin, vasopressin, or exogenous adrenocorticotropic hormone diminishes. Aniline thus inhibits corticosteroidogenesis at the adrenal level.
Weight Gain, Protein Utilization, and Liver Histochemistry of Rats Fed Low- and High-Thioglucoside-Content Rapeseed Meals
Authors: Oliver S. L. , McDonald B. E. , Opuszyńska T.
Published: April 2011

Utilization of a low-thioglucoside-content rapeseed meal (LoRSM) by growing rats was compared with that of a high-thioglucoside-content rapeseed meal (HiRSM) and casein (Cas). Each protein source served as the sole source of dietary nitrogen (2.4%). In experiment 1, three males and three females were allotted to each diet. Apparent protein digestibility was lower for the rapeseed meals (80 and 82%) than for casein (94%). However, 4-day nitrogen retention was significantly lower (P < 0.05) only for rats fed HiRSM (169, 440, and 526 mg for HiRSM, LoRSM, and Cas, respectively). In experiment 2, 48 rats were allotted to the same three diets for an 8-week growth study. Weight gains by rats fed Cas or LoRSM were nearly three times that of animals fed HiRSM. Thyroid size (milligrams per 100 g body weight) was similar for the LoRSM and Cas groups, whereas a pronounced thyroid enlargement as well as increased size of liver, kidneys, adrenals, and testes were observed in rats fed HiRSM. Histochemical examination of hepatic tissue revealed marked changes in activity and localization for acid and alkaline phosphatases and adenosine triphosphatase of animals fed HiRSM but only slight changes in the patterns of rats fed LoRSM. Males fed LoRSM and both sexes fed HiRSM exhibited lipid infiltration in the liver. The results suggest that thioglucosides are responsible for the poor performance reported for animals fed rapeseed meal.
Factors Affecting the Inactivation of Insulin-125I by Rat Adipose Tissue
Authors: Fessler Alfred , Rubinstein Bernard , Rubinstein David , Beck John C.
Published: April 2011

The degradation of insulin-125I by adipose tissue was determined by the appearance of 125I in the trichloroacetic acid (TCA) soluble tissue fraction. A maximum of 30% of the 125I appears as TCA-soluble material following incubation with adipose tissue homogenates. Destruction of immunoreactive insulin and insulin-like activities is, however, complete. The appearance of TCA-soluble 125I is due to proteolysis rather than to deiodination since it can be decreased by the addition of unlabelled insulin to the incubation mixture. No increase in free iodine could be detected. The degradation of insulin by intact adipose tissue is greater than by free adipocytes. Tissue homogenization greatly increases the rate of insulin degradation. Most of the insulin-degrading activity is found in the "fat-free" fraction of the tissue homogenate, but this activity is rapidly lost during incubation at 37 °C. In contrast the lesser activity in the fat layer remains stable at 37°. N-Ethylmaleimide, which inhibits breakdown of the hormone by homogenates, increases the degradation of insulin by adipocytes. These results indicate that caution must be employed in interpreting binding and destruction of iodinated insulin and raise the possibility that insulin may penetrate the cell prior to its destruction.
An Eserine-Like Action of Chloroquine
Authors: Garcia M. , Miyares C. , Sainz F.
Published: April 2011

High concentrations of chloroquine antagonize the hydrolysis of acetylcholine by acetylcholinesterase as well as by the pseudocholinesterase found in dog serum.