bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes associated with experimental skin calcification. II. Changes of lipid, water content, and minerals during calcium accumulation
Authors: Yoshinari T. , Sakai T. , Iida K. , Cruess R. L.
Published: April 2011

The biochemical changes associated with skin calcification following xylene rubbing and lead acetate treatment were studied. There was an increase in the water content of the local area and a decrease in the total lipids. There was an early decrease in percentage ash with a subsequent increase from 6 h onwards. The lead content increased to a maximum at 24 h and decreased slowly thereafter, and no relationship was found between phospholipids and calcification. It is suggested that lead may initiate the calcification, but once cutaneous calcification has been initiated, it continues even after the lead concentration of the skin begins to fall.
Further studies on the effect of various drugs on the uptake of tyramine-3H and formation of octopamine-3H in the rat heart
Authors: Commarato M. A. , Brody T. M. , McNeill J. H.
Published: April 2011

Pretreatment with desipramine, phenindamine, cocaine, and diphenhydramine significantly inhibited the conversion of tyramine-3H to octopamine-3H by the rat heart in vivo presumably by blocking the adrenergic neuronal uptake of the latter amine. Triprolidine pretreatment had no significant effect on amine uptake. These results are compared with previously reported data from this laboratory and show that the order of efficacy obtained with the drugs for the blockade of tyramine-3H uptake correlates well with their ability to block norepinephrine uptake and to inhibit the tyramine-induced increase in phosphorylase a activity. It is concluded that tyramine and norepinephrine utilize the same uptake system.
Reserpine supersensitivity to catecholamine-induced cardiac phosphorylase activation
Authors: McNeill John H.
Published: April 2011

Reserpine pretreatrnent in doses of 2.5 mg/kg or higher produced a supersensitivity to noradrenaline- or isoproterenol-induced activation of rat cardiac phosphorylase. The supersensitivity was not due to blockade of amine uptake since it was additive and differed in magnitude from the supersensitivity produced by tripelennamine. It is suggested that the supersensitivity may be related to reserpine-induced changes in intracellular calcium.
Effect of phytohemagglutinin on bone marrow protection and recovery in rodents
Authors: Plenderleith I. H.
Published: April 2011

Attempts were made to prevent the hematologic and general toxic effects of radiation, cyclophosphamide, and 6-mereaptopurine in various animal species by giving erythrocyte-absorbed phytohemagglutinin intravenously prior to or following such treatment. A single dose of total body radiation was used in the radiation studies, with mice receiving 800 and rats 600 rads. Cyclophosphamide was given to mice intraperitoneally in a dose of 0.25 mg/g of body weight on two occasions 6 days apart. 6-Mercaptopurine was given to other groups of mice intraperitoneally in a dose of 0.25 mg/g of body weight daily for 11 days and to rabbits subcutaneously in a dose of 0.01 to 0.015 mg/g of body weight daily for 14 days. No evidence of a protective effect or of enhanced recovery could be demonstrated in any of the animals treated with erythrocyte-absorbed phytohemagglutinin as compared with animals not so treated.
Comparative study of the metabolic fate of selenate, selenite, and sulfate ions in cartilage
Authors: Cipera J. D. , Hidiroglou M.
Published: April 2011

In vivo injections of three types of anions (75SeO3=, 75SeO4=, 35SO4=) into rabbits revealed a basic difference between the metabolic behavior of the selenium anions and that of sulfur anion in cartilage; whereas sulfate was incorporated predominantly into glycosaminoglycans, the entry of both selenium ions into this fraction was almost nonexistent. On the other hand, protein and lipid fractions isolated from cartilage had higher activity levels when selenium ions were injected than when sulfate was injected. In cartilage, the selenate activity disappeared at a faster rate than either selenite or sulfate. In blood sera the rate of activity disappearance was higher with both selenate and sulfate than with selenite.
Comparison of 131I retention in the plasma of rabbits fed toxic quantities of cupric or molybdate ions as supplements to a commercial pelleted diet or to an oats–alfalfa laboratory diet
Authors: Pepino Anne McCarter , Robinson G. A. , Chou S. T. , Liptrap R. M.
Published: April 2011

The retention of 131I in the protein-free plasma of rabbits fed a commercial diet has been reported previously. In the present study an attempt was made to defeat this retention by feeding or by intramuscular injection of cupric acetate solution. Copper did not reverse the retention; conversely, copper was more effective in producing the retention than was molybdate. The effect of copper plus molybdate was not cumulative, nor did one ion appear to reverse the retention caused by the other. Acute starvation produced a more extensive 131I retention than did highly toxic levels of copper. 131I retention was also observed for rabbits fed an oats–alfalfa laboratory diet even in dietary groups receiving no added molybdate or copper. Seventy-two hours after the injection of 131I, the oats–alfalfa control groups showed a 131I concentration in protein-free plasma approximately 50 times that of control rabbits fed the commercial diet. The common factor in the 131I retention is believed to be relative partial starvation because of nutritional deficiency or lack of palatability of the diet, or the fact that the rabbits became too ill to eat normal quantities of food.
Evidence for the nephrotoxicity of morphine sulfate in rats
Authors: Marchand Claude , Cantin Marc , Côté Michel
Published: April 2011

Chronic administration of morphine sulfate to rats caused a decrease in accumulation of p-aminohippurate (PAH) by renal cortex slices. No apparent effect on PAH accumulation was observed following a single injection of morphine or when the narcotic was added directly to the incubation medium. Electron microscopic studies showed marked changes in the morphology of the kidney in morphine-treated rats; inconstant but massive macroscopic and microscopic lesions were observed in the renal cortex, medulla, and papilla of rats treated chronically with the narcotic.
Catecholamines and cold thermogenesis in sheep
Authors: Webster A. J. F. , Heitman J. H. , Hays F. L. , Olynyk G. P.
Published: April 2011

Experiments were performed to assess the role of catecholamines in cold thermogenesis in warm- and cold-acclimated adult sheep. Urinary excretion of both noradrenaline and adrenaline increased in sheep exposed to cold. Propranolol (1 mg/kg) reduced cold thermogenesis in warm- and cold-acclimated sheep by 8% and 12% respectively. Noradrenaline and adrenaline infusions at 1 μg/kg min for 30 min had no significant effect on the rate of heat production of warm- or cold-acclimated sheep. Phenoxybenzamine (3.0 mg/kg) almost abolished cold thermogenesis in warm-acclimated sheep. Cold-acclimated animals treated with phenoxybenzamine were able to maintain homeothermy during severe cold stress. These findings support previous reports which suggest that catecholamines are involved in metabolic cold acclimation in the sheep, but indicate clearly that they have no direct thermogenic effect in cold-acclimated adults of this species.
The effect of moderate exercise on the regional distribution of blood flow in the rat
Authors: Stevens E. Don
Published: April 2011

The effect of moderate exercise on cardiac output and its distribution was studied in the rat. During moderate exercise blood flow to the skeletal and heart muscle increased. The decrease in the flow fraction of the cardiac output to the splanchnic bed and kidneys was offset by the increase in cardiac output so that blood flow to these organs was maintained during exercise. Blood flow decreased to the spleen and to that area of skin overlying the tail during moderate exercise. Thus, the tissues associated with the increased oxygen demand during exercise profited most from the increased cardiac output.
The effect of some CNS depressants on the hypermotility and anorexia induced by amphetamine in rats
Authors: Borella L. E. , Paquette R. , Herr F.
Published: April 2011

This study examines the effects of chlorpromazine, tetrabenazine, and chlordiazepoxide on the hypermotility and anorexia caused by amphetamine 11.5 mg/kg per os in rats. Each CNS depressant was used at three dose levels and was administered simultaneously with amphetamine. Chlorpromazine, 2 mg/kg, potentiated the hypermotility caused by amphetamine as measured in jiggle cages. Higher doses antagonized amphetamine stimulation. In rats which were trained to eat during a 5-h period, all doses of chlorpromazine potentiated amphetamine anorexia. Tetrabenazine antagonized amphetamine stimulation but did not affect its anorexic effect. Chlordiazepoxide antagonized both effects of amphetamine.
Water intake of normal and desalivate rats on exposure to environmental heat
Authors: Lund J. P. , Barker J. H. , Dellow P. G. , Stevenson J. A. F.
Published: April 2011

The water intakes of desalivate and normal male rats were compared before, during, and after 5 h of heat stress (36 °C). Increased drinking occurred in both groups during the first 30 min of heat exposure The intakes were low and essentially similar for the next 90 min in the heat; after this period the controls drank significantly more water than the desalivate rats. Colonic temperatures were elevated only in the desalivate group during heat exposure; temperatures fell to subnormal levels in all animals after return to the 22 °C environment. From these findings it is postulated that stimulation of thermoreceptors, probably peripheral, is responsible for the drinking that occurs immediately upon heat exposure. Dehydration would not appear to cause an increase in water intake until longer exposure and significant water loss have occurred.
Turnover rates of D-isoascorbic acid and L-ascorbic acid in guinea pig organs
Authors: Pelletier Omer
Published: April 2011

To elucidate the mode of action of D-isoascorbic acid (IAA) in exerting vitamin C activity for guinea pigs, it was necessary to determine the turnover rate of this ascorbic acid in their organs as well as its effect on the turnover of L-ascorbic acid (AA). Guinea pigs were saturated with either IAA or AA, and the organ contents of the isomers were determined at different intervals of depletion. In a second experiment, guinea pigs previously saturated with AA were injected intraperitoneally with L-ascorbic-1-14C acid. Twenty-four hours after injection, L-ascorbic-1-14C acid was measured in the organs of some of the animals; three groups were formed with the other animals: group 1 was fed with a diet deficient in vitamin C, group 2 with the diet plus 0.1% AA, and group 3 with the diet plus 2% IAA. The L-ascorbic-1-14C acid content of the organs was determined on different days. It was found that the rate of IAA turnover was much more rapid than that of AA in all organs. Furthermore, IAA increased rather than decreased the turnover of AA.
Changing physiological relationships in men under acute cold stress
Authors: O'Hanlon Jr. James F. , Horvath Steven M.
Published: April 2011

Thirty-four men were exposed to 8 °C for 2 h. Their reactions were studied to indicate how physiological relationships change during exposure to cold. Measurements of various body temperatures, MST, MBT, body heat content (BHC), [Formula: see text], heat production, and heart rate (HR) were made before the onset of and periodically during cold exposure. Various skin temperatures fell to different levels while rectal temperature rose slightly, then fell 0.3 °C by the end of the exposure. BHC declined by 6%, [Formula: see text] nearly doubled, [Formula: see text] and heat production increased by 66 and 75% respectively, and HR changed little during cold exposure. Relationships which changed most significantly during cold exposure were those between MST and rectal temperature, certain skin temperatures and rectal temperature, [Formula: see text] (also heat production) and BHC, [Formula: see text] and rectal temperature, and finally, those between every body temperature and the age of the subjects. Relationships which also changed were those between finger and toe temperature as well as those between [Formula: see text] (also heat production) and each of the following: [Formula: see text], rectal temperature, thigh temperature, HR, and age. These results indicated that (1) temperature in the upper extremities was actively maintained at a higher level than temperature in the lower extremities, (2) increased metabolism became a progressively more effective adaptation than redistribution of blood volume, (3) subjects with the lowest BHC tended to increase their metabolism the most, (4) [Formula: see text] was inversely related to core temperature after the latter fell below normal, (5) HR was unrelated to the increase in [Formula: see text], (6) the usual inverse relationship between age and metabolism was not found in the cold, and finally, (7) older subjects generally tended to maintain higher body temperatures than younger subjects.
Variations in air viscosity due to changes in water vapor pressure for isothermal conditions at temperatures below 40 °C
Authors: Roy P. D. , Josenhans W. T. , Miller C. H.
Published: April 2011

The viscosities of moist and dry air were measured at four temperatures to determine variations due to changes in water vapor content under isothermal test conditions. Paired measurements (240) of volumetric rates of air flow and pressure drops along a tube were made. Corresponding coefficients of viscosity were calculated from the Hagen–Poiseuille equation, laminar flow being assured by limiting maximal Reynolds numbers. The relationship between viscosity (η) and water vapor pressure [Formula: see text] was found to be approximately linear. The increase in the work load of the respiratory muscles due to an increase in air humidity, and hence viscosity, from purely physical considerations, appears to be very small compared with the total work of breathing.
Shivering and nonshivering thermogenesis in the bat (Myotis myotis Borkh.) during arousal from hibernation
Authors: Mejsnar Jiří , Janský Ladislav
Published: April 2011

Nonshivering thermogenesis exists in the bat (Myotis myotis Borkh.) arousing from hibernation at environmental temperatures of 4–6 °C. Nonshivering thermogenesis is essential for the start of the arousal, and it is stimulated by noradrenaline since hexamethonium prevents the increase in metabolism and body temperature. Injection of noradrenaline abolishes this inhibition by hexamethonium by inducing nonshivering thermogenesis. After simultaneous administration of hexamethonium and alderlin no calorigenic effect of noradrenaline occurs. Shivering heat production during arousal appears at body temperatures between 10 and 17 °C predominantly. In normothermic bats the calorigenic effect of noradrenaline was observed, which indicates that nonshivering thermogenesis might also be present in awake animals. During arousal at 25 °C a great increase in intensity of shivering was observed. Elimination of nonshivering thermogenesis by hexamethonium does not prevent the attainment of the homoiothermic level of body temperature, and administration of noradrenaline does not speed up the process of arousal. As is evident from the metabolic capacity of the brown fat, the heat derived from this organ could maximally participate in total metabolism by 25% at the beginning and at the late period of arousal. In the middle range of body temperatures its significance for total metabolism is only about 10–13%.
A decerebration technique for studies on the cerebral cortex
Authors: Brown J. D. , Pinsky C.
Published: April 2011

A posterior fossa approach is described for midbrain transection in the cat. This method has the advantage of reducing the period of anesthesia usually required for subsequent surgical procedures.
The effect of level of protein on protein quality of lysine-deficient foods
Authors: Yanez E. , McLaughlan J. M.
Published: April 2011

Nitrogen intakes and weight changes of male weanling Wistar rats fed two or more levels of test proteins or a non-protein diet for 2 weeks were determined. The slope-ratio plot for multiple-dose assays showed clearly that proteins markedly deficient in lysine yielded invalid assays. NPR values for lysine-deficient protein were markedly higher when determined at the 5% than at the 10% level of protein but foods limiting in methionine, threonine, or lysine and threonine yielded similar values at the two levels of dietary protein. It was concluded that protein quality per se is not a fixed value and depends on the level of protein fed even at low and moderate concentrations. When PER, NPR, and slope-ratio values for several samples were expressed as a percentage of the values for casein, NPR and slope-ratio methods gave almost identical results but PER yielded low values for poor quality proteins. However, the three methods rated the eight test proteins in the same relative order.
Relationship between viscosity and hematocrit in blood of normal persons and burn patients
Authors: Zingg Walter , Sulev Judith C. , Morgan Christopher D.
Published: April 2011

The relationship between hematocrit and blood viscosity was investigated in fresh blood samples obtained from a control group of normal persons and from a group of patients with burns. Barras' equation describing the percent change in blood viscosity caused by a change of 1% in the hematocrit was found useful for the quantitative assessment of the relationship between whole blood viscosity and hematocrit. Although individual variations were observed, the average change in viscosity per 1% hematocrit change was identical in the control group and the burn patients, the value being close to that reported by Barras. Analysis of covariance showed an increased blood viscosity independent of the hematocrit in the burned patients as compared with the controls.
Some effects of ethanol on the toxicity and distribution of barbiturates in rats
Authors: Coldwell Blake B. , Wiberg G. Stuart , Trenholm H. Locksley
Published: April 2011

The interaction of ethanol with amobarbital, barbital, pentobarbital, phenobarbital, and thiopental was investigated at both the pharmacological and metabolic levels in rats. Induction time was shortened and sleeping time lengthened by the administration of ethanol with each of the five barbiturates, the effects being most pronounced with barbital and phenobarbital. Brain levels of barbital, phenobarbital, acetaldehyde, and acetone were increased by ethanol. Rats given amobarbital, pentobarbital, and thiopental had significantly higher brain and serum barbiturate levels at the time of regain of the righting reflex than was present in rats given these barbiturates with ethanol, indicating that the CNS depression was not dependent only on the concentration of barbiturate in the brain. The decay profiles of serum barbiturate concentrations were not altered by ethanol, and the barbiturates had no effect on the brain and blood ethanol levels. Phenobarbital depressed blood and brain acetaldehyde levels, but not the acetone levels, in ethanol-treated animals. Pentobarbital and thiopental, alone or with ethanol, had no effect on the blood acetaldehyde levels but increased the brain acetaldehyde levels in ethanol-treated animals. Pentobarbital had no effect on blood acetone or acetaldehyde levels but increased the brain levels of these compounds and, when administered with ethanol, decreased the brain acetone concentration. Thiopental increased the blood acetone level and when administered to ethanol-treated animals decreased the brain acetone levels.
Paraoxon and parathion: effects of daily administration on vitamin E levels in male rats
Authors: Goyer G. R. , Martin E. A. , Paganuzzi P. , Brodeur J.
Published: April 2011

The effect of daily administration of parathion and paraoxon on hepatic stores and plasma concentrations of vitamin E was studied in the immature male rat. Parathion or paraoxon (30 p.p.m.) was added to the daily diet of various groups of eight immature animals (70 to 90 g). Control groups received a basic rat diet. At intervals of 2, 4, and 8 weeks after the beginning of treatment, control and treated animals were killed. A significant decrease in the body weight of the treated animals was noticed during the first 2 weeks of treatment. Food intake, liver weight, and plasma and liver tocopherol concentrations were not modified throughout the experiments in treated animals by comparison with controls. A marked inhibition of brain acetylcholinesterase activity (81%) was observed after 1 week of treatment with either parathion or paraoxon. During the following weeks, a slight recovery of acetylcholinesterase activity was observed in the paraoxon-treated groups: indeed, the cholinesterase inhibition decreased from 81% to 67% after 8 weeks. With parathion-treated animals, the recovery was more pronounced as the cholinesterase inhibition decreased from 81% to 33% after 8 weeks. Additional experiments revealed that the metabolism of paraoxon or parathion by liver homogenates was not stimulated in chronically treated rats. Thus, chronic administration of paraoxon or parathion does not seem to interfere with liver and plasma levels of vitamin E.
The effect of posture on the capillary filtration rate in the human forearm
Authors: Newberry P. D. , McDonald J. M. , Rowe E. R.
Published: April 2011

A water-filled plethysmograph of a new design was used to measure the capillary filtration rate in the left forearm of each of six male subjects at a room temperature of 27 °C, in the supine and the seated positions. The adoption of the seated position resulted in a decrease of the capillary filtration rate by an average of 0.050 ± 0.015 S.E. ml/min∙100 ml (p < 0.02) and in an increase of the average threshold venous pressure for capillary filtration from 14 to 26 mm Hg (p < 0.01). This change was associated with an increase in the post-capillary resistance. Adoption of the seated position caused no significant change in the capillary filtration coefficient.
Smooth muscle contraction and viscoelasticity of arterial wall
Authors: Wurzel M. , Cowper G. R. , McCooK James M.
Published: April 2011

Elasticity and viscosity, of fully relaxed and gradedly contracted arterial wall, were measured on spirally cut rabbit aortic strips suspended in Ringer's solution. Pre-extended contracted tissue submitted to additional stretch shows an instantaneous and a slow elongation. Only instantaneous elongation was observed on fully relaxed tissue. This behavior can be simulated by a mechanical model consisting of a spring in series with a dashpot, and a second spring in parallel with the first spring–dashpot component. The modulus of the first spring and the coefficient of viscosity both increase steadily with increasing contraction, while the modulus of the second spring decreases. The first spring–dashpot component is believed to represent the viscoelastic behavior of smooth muscle on its non-contractile network. The second spring probably represents the combined elastic properties of arterial elastin and collagen.
Glyceride–glycerol release and the interconversion of glucose and glycerol in normal and fasted rats
Authors: DeFreitas A. S. W. , Depocas Florent
Published: April 2011

Specific activities of plasma glycerol, plasma glucose, and respiratory CO2 were determined during continuous intra-arterial infusion of trace amounts of glycerol uniformly labelled with 14C into normal and 24-h fasted white rats. The same measurements were made in other rats during primed continuous infusion of glucose uniformly labelled with 14C. The data were analyzed by means of a previously described two-pool model in material and isotopic steady state. The two major precursors of plasma glycerol were considered to be glycerol from triglyceride hydrolysis and glycerol derived from glycolytic intermediates formed during the metabolism of glucose or glucogenic amino acids. The model allowed quantitative assessment of each source. In normal adult rats the rate of total net formation of plasma glycerol was 0.27 mg carbon per min per rat of which about 30% was ascribed to glyceride–glycerol release and 70% to net formation of glycerol from glycolytic intermediates. In fasted rats, the rate of total net formation of glycerol was 0.23 mg glycerol carbon per min of which 83% was ascribed to glyceride–glycerol release and 17% to formation from glycolytic intermediates. Only 4% of the rate of total net formation of glucose could be attributed to net formation of glucose from glyceride–glycerol in normal rats whereas this increased to 18% in the fasted rat. Contrary to previous reports these results indicate that glyceride–glycerol is not the major gluconeogenic substance in the fasted rat.
Contralateral projection of some cells of the lateral reticular nucleus
Authors: Crichlow Eugene C.
Published: April 2011

Cells of the lateral reticular nucleus were antidromically fired by stimulation of the paramedian lobules. These cells fell into three classes: those activated solely by ipsilateral paramedian stimulation, those which responded only to stimulation of the contralateral paramedian, and, finally, those cells which fired to stimulation of both paramedian lobules. These findings indicate that in addition to the known ipsilateral paramedian projection some cells of the lateral reticular nucleus send their axons to the contralateral paramedian lobule, whereas others project to both paramedian lobules.
Changes in specific airway resistance during prolonged breathing of moist air
Authors: Melville G. Norris , Josenhans W. T. , Ulmer W. T.
Published: April 2011

Effects of increased water content of inspired air at 21–38 °C on specific airway resistance (sRaw) in 107 healthy subjects were measured with a body plethysmograph. Mean sRaw increased insignificantly at 23 °C with 92% relative humidity (water content, 20.7 g∙m−3) for up to 71 h but became significant at 6 h with water content 25 g∙m−3. Increases were greater when evaporated tap water was inhaled than when distilled water was used. It is postulated that the increase in sRaw is due to mucosal swelling and to contaminants in tap water. A theory of respiratory "water elimination" is proposed to replace the concept of respiratory water loss.
The effect of loading doses of unlabeled methionine on the oxidative catabolism of 14C-labeled histidine and serine in vivo
Authors: Tran N. , Winchell H. S.
Published: April 2011

A significant effect of loading doses of unlabeled L-methionine resulting in decreased 14CO2 production in the breath of normal rats after the intravenous administration of L-histidine-(imidazofe-2-14C) and L-serine-3-14C was demonstrated in vivo. These results suggest that L-methionine inhibited the physical transport of several amino acids across the cell membrane in normal rats. The 14CO2 breath analysis using an ionization chamber method offers great promise for in vivo metabolic studies involving competition between various substrates in the animal.
Sodium and potassium exchanges in adrenalectomized rats administered deoxycorticosterone chronically
Authors: Fregly Melvin J. , Kim Ku Ja
Published: April 2011

Fifteen male adrenalectomized rats were divided into three equal groups and given powdered Purina diet and a choice between 0.30 M NaCl solution and distilled water. Body weight, intakes of food and fluids, urine output, and urine sodium and potassium concentrations were measured daily during a 7-day control period. At this time, two of the groups were administered 250 and 500 μg deoxycorticosterone acetate (DOCA) per kg body weight per day s.c. in oil. Controls received oil. The measurements listed above were taken for an additional 11 days of treatment. All groups ingested more NaCl solution than water during the control period. When DOCA was begun, both sodium output (meq/day) and intake (meq/day) were reduced proportionately and the linear relationship between them observed before treatment was maintained. Under these conditions adrenalectomized rats failed to escape from the sodium-retaining effects of DOCA. Furthermore, both the reduced output and intake of sodium remained for 10 days after drug administration ceased. Although administration of DOCA increased potassium excretion, food intake also increased such that the relationship between potassium intake and output observed before treatment was maintained. The urinary Na/K ratio was reduced significantly during drug treatment. The results suggest that mineralo-corticoid hormones are important in the control of both output and intake of sodium in the rat.
Urinary excretion of 17-ketosteroids by normally fed and severely underfed boars
Authors: Stefanovic M. P. , Bayley H. S. , Slinger S. J.
Published: April 2011

Two boars were fed normally to 19 weeks of age and then underfed so that their growth was severely restricted. Two other boars were underfed to 19 weeks of age and thus did not grow; they were then normally fed and the experiment was continued until they reached the same weight as the first two boars. The excretion of 17-ketosteroids (17-KS) in the urine of the four boars was measured on 2 days each week by separating their trimethylsilyl ethers by gas–liquid chromatography. The excretion of 17-KS reached a maximum of 9.0 mg per day for the boars which were fed normally in the first part of the experiment. Reducing their allocation of feed did not have an immediate effect on the excretion of total 17-KS, but after 4 weeks the excretion declined to about 1.0 mg per day. The 17-KS excretion of the boars which were underfed initially remained less than 0.5 mg per day, but increased when the feed allocation and hence growth rate of the boars increased. However, the excretion of 17-KS by these boars did not reach the levels recorded for the boars which had grown normally from the start of the experiment.
A Pharmacodynamic Study of DDT in Rabbits following Acute Intravenous Administration
Authors: Black W. D. , Ecobichon D. J.
Published: April 2011

Emulsified DDT was administered as a single intravenous dose to nonpregnant female rabbits at concentrations of 150, 100, 50, 25, and 12.5 mg/kg. Tremors and convulsions were observed in all animals receiving more than 12.5 mg/kg. Since DDT at 150 mg/kg proved lethal at an average time of 95.8 min, the animals receiving lower doses were sacrificed at 96 min. The results demonstrated that the distribution of an acute dose of a lipophilic insecticide to various tissues depended largely upon (1) hemodynamic factors such as the blood flow in the tissue, (2) the capillary density, and (3) the distribution of blood to various tissues from the site of injection. A positive correlation was observed between plasma levels of DDT and those found in the brain. The severity of the clinical signs of DDT poisoning coincided with the levels detected in the brain. In addition to whole brain assays, the DDT content of various regions of gray and white matter was determined in rabbits treated with 50 mg DDT/kg. The incidence of tremor coincided closely with the high levels detected in gray matter (cerebellum and neocortex). Predominantly white matter (brainstem and spinal cord) had significantly lower concentrations.
A Comparison of Na+ Activation of ATPase in the Red Cell, Renal Cortex, and Renal Medulla
Authors: Cole C. H. , Dirks J. H.
Published: April 2011

In vitro Na activation of the ATP hydrolyzing enzyme system in human red cell membranes and in microsomes prepared from various sites in the dog kidney was studied. Marked differences between red cell and renal ATPase were noted. Red cell ouabain-sensitive ATPase, which required 4.2 mM of Na+ for half maximal activation, was markedly inhibited by concentrations of Na+ of 300 mM. Medullary ouabain-sensitive ATPase required 19 mM of Na+ for half maximal activation and was not significantly inhibited by 300 mM of Na+. These studies show that renal ouabain-sensitive ATPase is capable of functioning maximally in an in vitro environment which simulates, with respect to Na+ concentration, that of the renal medullary interstitium. Thus it is not unreasonable to hypothesize that this enzyme may play a role in Na transport in the renal medulla.
The Acute Effect of Some Chlorinated Hydrocarbon Insecticides on the Acetylcholine Content of Rat Brain
Authors: Omer Vincent V. St. , Ecobichon Donald J.
Published: April 2011

Changes in total brain acetylcholine (ACh) levels as related to convulsive activity were followed after the intracarotid administration of four structurally unrelated chlorinated hydrocarbon insecticides to rats. ACh levels were determined by gas chromatography. The level of ACh found in cannulated controls was 4.7 ± 0.5 (S.E.M.) μg/g fresh tissue. Lindane raised the ACh level (μg/g) to 3.5–6.7, dieldrin to 8.5–9.7, heptachlor to 6.5–10.7, and DDT to 8.8–10.9. The order of neurotoxic signs was lindane > dieldrin > heptachlor > DDT.
Inhibitory Effect of Beta-Hydroxybutyrate on Lipolysis Stimulated by Dihydroergotamine and Growth Hormone In Vitro
Authors: Hotta Nigishi , Sirek Anna , Sirek Otakar V.
Published: April 2011

The sodium salt of beta-hydroxybutyric acid was added to the incubation medium of isolated rat adipose tissue cells at an 8 mM concentration. The keto-acid had no effect on basal lipolysis in terms of release of glycerol and free fatty acids. Beta-hydroxybutyrate strongly inhibited the lipolytic effect of (a) dihydroergotamine (DHE), (b) growth hormone (GH) and dexa-methasone, and (c) DHE, GH, and dexamethasone. These results provide further evidence that ketones inhibit lipolysis stimulated by hormones and other agents. It is implied that the lack of a lipolytic effect of the DHE–GH combination in pancreatectomized animals (Sirek et al. 1969) is at least in part the result of accumulated ketone bodies in plasma.
Further Evidence for 'Active' Reflex Vasodilatation
Authors: Wyse D. G. , Beck L. , Burks T. F. , Spalding C. T.
Published: April 2011

Further experimental evidence has been presented which strengthens the hypothesis of active reflex dilatation. The administration of a ganglionic blocking agent in a dose sufficient to block completely adrenergic tone failed to lower the perfusion pressure in the isolated extremity to the same level as was reached during the nadir of reflex dilatation. Thus, it is reaffirmed that simple withdrawal of adrenergic vascular tone (passive reflex dilatation) cannot entirely account for the total magnitude of reflex dilatation. Although chronic reserpine pretreatment eliminated both reflex constriction and dilatation, acute reserpine administration reduced reflex dilatation at a time when reflex constriction and perfusion pressure were little affected. On the other hand, the administration of the substituted phenothiazine, methotrimeprazine, eliminated adrenergic tone but had little effect on reflex dilatation. The latter two types of experiment provide further important dissociations between reflex dilatation and inhibition of existing adrenergic activity. Administration of cocaine by several different routes reduced reflex dilatation, but the reduction in reflex dilatation does not appear to be due to inhibition of reuptake of adrenergic amine. Neither does blockade of active reflex dilatation by the antihistamine, tripelennamine, appear to be related to its possible ability to block reuptake of adrenergic amine. Classic autoregulatory stimuli fail to elicit a response analogous to active reflex vasodilatation, and antihistamines fail to alter autoregulatory readjustments while reducing very effectively active reflex vasodilatation.
Effects of Inhibitors of Metabolism on Adenine Nucleotides and on 22Na and 42K and Net Movements in Rat Uteri at 25 °C
Authors: Daniel E. E. , Robinson Kathleen
Published: April 2011

The effects of 10−3 M iodoacetate (IAA) and (or) 10−3 M dinitrophenol (DNP) on Na and K fluxes and contents and on adenine nucleotide levels of isolated rat uterine horns were studied. Early 22Na efflux was slightly increased by DNP in the fresh and Na-rich tissues. IAA and DNP alone or together reduced 22Na efflux from the larger cellular fraction (No. 2) in both fresh and Na-rich tissues. 22Na efflux from the smaller cellular fraction (No. 3) was accelerated by IAA and by DNP in Na-rich tissues. DNP increased 22Na influx in both types of tissue and caused net Na gain and K loss. In fresh tissues IAA or IAA plus DNP accelerated 22Na influx, but slowed this influx in Na-rich tissues. In fresh tissues the ATP content was reduced by 50% by DNP. After a 60-min exposure with IAA and a 15- to 20-min exposure with IAA plus DNP, the ATP levels were negligible. The onsets of action of IAA or of IAA plus DNP on Na fluxes were correlated with ATP depletion, but early acceleration of 22Na efflux by DNP was not. In fresh tissues 42K influx was slightly decreased at the time of ATP depletion and the influx was further slowed as tissue potassium was replaced by sodium. IAA plus DNP increased K efflux in 10 min and IAA alone increased K efflux after 100 min. Thus K flux changes were not well correlated with ATP depletion. Substitution of K for all the sodium in the bathing media did not alter the quality of the effects of IAA or IAA plus DNP on sodium efflux. When prolonged glucose depletion eliminated ATP and ADP, the effects of IAA could not be duplicated. But IAA alone, or with DNP, still caused alterations in the 22Na efflux. Therefore IAA acted on ion fluxes by a mechanism other than ATP depletion. Both fresh and Na-rich tissues swelled after ATP depletion. An effect on internal osmotic pressure rather than ATP-depletion per se was postulated. Other studies showed that Na-rich tissues were resistant to shrinking by hypertonic sucrose and became more so secondarily after ATP depletion because of increased sucrose permeability. Evidence from studies of swelling, as well as flux data, suggested that at least two Na pumps were present. Both were ATP-dependent. One was ouabain-sensitive and exchanged Na for K, while the other was ouabain-insensitive and controlled movement of Na with water.
Electrical Resistance and Volume Flow in Glass Microelectrodes
Authors: Firth D. R. , DeFelice L. J.
Published: April 2011

The electrical resistance and the flow of solution in glass microelectrodes has been studied as function of the concentration of internal and external solution (KCl, 3–10−5 M), and as a function of pressure between the inside and outside solutions. The study demonstrates the usefulness of using microelectrodes for measuring cell membrane resistance and also the dangers in using them as microejectors because of anomalous flow effects. Electrokinetic effects and tip potentials are briefly described; they offer a means of investigating the surface condition of the glass wall inside the tip of the electrode and its variation with the outside solution.
The Effect of Lidocaine on Twitch Potentiation and Repetitive Neural ActivityProduced by Soman and Neostigmine
Authors: Lowndes H. , Johnson D. D.
Published: April 2011

Soman and neostigmine produce twitch potentiation in the isolated rat phrenic nerve – diaphragm preparation by initiating repetitive electrical activity at neuromuscular junctions. This is associated with repetitive impulses in the phrenic nerve. Lidocaine abolishes the repetitive firing in both the phrenic nerve and diaphragm. This effect is produced by concentrations of lidocaine that have no effect on normal neuromuscular function as indicated by the absence of an effect on normal twitch or tetanic responses. These results indicate that the mechanism by which lidocaine abolishes drug-induced twitch potentiation involves the presynaptic nerve terminals.
A Study of the Renal Excretion of Calcium by the Production of a Constant Level of Hypercalcemia in Normal and Abnormal Human Subjects
Authors: Shaw William H.
Published: April 2011

The relationship between urinary calcium excretion and serum calcium was studied at stable serum calcium levels, both normal and elevated. The linearity of this relationship being known, the slope of this line could be determined by sampling only at its lower and upper ends, that is, by measuring urine and serum calcium at a resting level and at a constant level of hypercalcemia produced by a calcium infusion. This method permitted three sets of measurements at each of the two levels, and also tended to eliminate the factor of renal delay time. The procedure was performed with normal subjects, with normals given vitamin D2 or parathyroid extract, and with subjects having hyperparathyroidism, sarcoidosis, and recurrent renal calculi. In the normal subjects the gradient of the slope appeared to indicate that there is no maximal tubular reabsorptive capacity for calcium, in the range sampled at any rate. The slopes of the various abnormal subjects mostly did not differ markedly from those of the normals. One incidental finding was that resting levels of urinary calcium excretion were significantly depressed 24 h following vitamin D2 administration, despite unchanged serum calcium levels.
Inhibition of Human Platelet Aggregation by a Dibenzazepine Compound (GP 44296) and by N-(2,6-dichlorophenyl)-o-aminophenylacetic acid(GP 45840)
Authors: Jobin François , Gagnon France T.
Published: April 2011

Studies of the aggregation of human platelets indicate that compounds GP 44296 and GP 45840 inhibit the secondary phase of ADP-induced aggregation and collagen-induced aggregation; GP 44296 also inhibits the primary phase of ADP-induced aggregation. Our results suggest that these compounds are more active on platelet behavior in vitro than phenylbutazone, oxyphenbutazone, and sulfinpyrazone.
Perfusion of the Anterior Septal Artery in the Canine Heart
Authors: Amir-Jahed A. K. , Fakouhi T. A.
Published: April 2011

The major arterial supply to the septum of the canine heart is by the anterior septal artery which supplies mainly the caudal portion of the interatrial and the upper two-thirds of the interventricular septum. Thus, perfusion of this artery assures a rather selective effect upon the atrioventricular (A-V) node and A-V conduction system.The method of perfusion of the anterior septal artery described in this communication may be used for the production and study of reversible arrhythmias of short duration and for the study of the effect of pharmacologic agents upon the A-V conduction system, and compares favorably with other methods of coronary artery perfusion.
Inhibition by Oxytetracycline of the Development of the Enhanced Response to Noradrenaline in Cold-Acclimated Rats: A New Approach to the Study of Nonshivering Thermogenesis
Authors: Himms–Hagen Jean
Published: April 2011

The aim of these experiments was to depress the increased metabolic activity of the brown adipose tissue in the intact rat during acclimation to cold in order to elucidate further the possible thermogenic and endocrine functions of this tissue. The antibiotic oxytetracycline was administered twice daily for 2 weeks to rats living at 4 °C in an attempt to inhibit the proliferation of mitochondria and of mitochondrial inner membrane known to occur in the brown adipose tissue in response to cold; control rats received saline during the same period. Total cytochrome oxidase activity served as an index of the amount of mitochondrial inner membrane in brown adipose tissue, liver, and skeletal muscle. The development of an enhanced calorigenic response to intravenously infused noradrenaline served as an index of the extent of acclimation to cold.Treatment with oxytetracycline inhibited both the cold-induced increase in cytochrome oxidase activity in brown adipose tissue and the cold-induced development of an enhanced calorigenic response to noradrenaline in the intact rats; a direct correlation was noted between the amount of cytochrome oxidase in brown adipose tissue and the size of the metabolic response to noradrenaline of the intact animals. However, the amount of oxygen that could be consumed by the total cytochrome oxidase in the brown adipose tissue was itself too small to account for the increase in oxygen consumption by the rat. Treatment of the rats with oxytetracycline did not alter the cold-induced growth of brown adipose tissue (as judged by the increase in wet weight and the increase in total protein); it also did not alter the cytochrome oxidase activities of liver or skeletal muscle. The effect of oxytetracycline seems, therefore, to be fairly specific for the mitochondria of the most rapidly dividing tissue, the brown adipose tissue. The conclusion is drawn that a protein synthesized in the mitochondria of the brown adipose tissue in response to cold is essential for adaptation to cold.
Respiration and Insulin Synthesis in the Islets of Langerhans
Authors: Lin B. J. , Haist R. E.
Published: April 2011

A new radiorespirometric apparatus is described. It permits a simultaneous estimation of proinsulin and insulin and of carbon dioxide production by the isolated pancreatic islets. The results show that the carbon dioxide production from labeled glucose, mannose, fructose, ribose, and xylitol correlates very well with the amount of proinsulin and insulin newly synthesized by the isolated rat islets. In the presence of glucose, the greatest carbon dioxide production was obtained and the largest quantity of proinsulin and insulin was synthesized. Mannose was metabolized to carbon dioxide at two-thirds the rate of glucose and was also two-thirds as effective as glucose in stimulating insulin synthesis. Very little of fructose, ribose, and xylitol were metabolized to carbon dioxide and very little proinsulin and insulin were produced in their presence. It was also observed that the presence of xylitol did not alter the rate of metabolism of glucose to carbon dioxide by the islets. In contrast, although pyruvate was metabolized to carbon dioxide very well, little insulin was synthesized in its presence.These results confirmed our previous findings and lent further evidence to our suggestion that the biosynthesis of proinsulin and insulin depends not only on the provision of energy and substrate but also on some 'triggering' factor or factors produced during the metabolism of glucose and mannose by the pancreatic islets.
Action de l'Acide Dipropylacétique Chez le Papio papio Photosensible
Authors: Patry G. , Naquet R.
Published: April 2011

It has been recently proved that n-dipropylacetate increases the level of cerebral γ-aminobutyric acid. Intravenous injections of various doses of the former were administered to eight baboons (Papio papio) that were more or less photosensitive and exhibited convulsive seizures.

The results show that n-dipropylacetate can protect (although usually only briefly) against clinical manifestations, and less effectively against EEG manifestations, induced by intermittent light stimulation. Furthermore, protection against grand-mal discharges seems to outlast protection against myoclonic discharges.
Single Influx Rate for 42K+ in the Single Fiber of the Barnacle
Authors: Allen R. D. , Hinke J. A. M.
Published: April 2011

The influx of 42K+ was measured in single muscle fibers of the giant barnacle Balanus nubilus. In influx experiments for 54 h, only one exchange component was evident for up to 90% intracellular K+. A comparison of this result with intracellular K+ activity measurements using K+-selective microelectrodes indicates at least 90% of the intracellular K+ is free in the myoplasm.