bluuebunny/crossref_metadata_2025 huggingface dataset:
Fetal brain oxygen
Authors: Misrahy G. A. , Beran A. V. , Spradley J. F. , Garwood V. P.
Published: December 2017

A polarographic technique for acute and chronic recordings of fetal and maternal oxygen availability (aO2) was developed. Fetal brain oxygen availability equaled maternal and neonatal oxygen availability when the uterus was quiescent. During uterine contractions or when pressure was applied to the fetal head, O2 availability was greatly diminished. During labor the fetal O2 diminished considerably but recovered rapidly after delivery. Apresoline, Levophed, adrenaline, Pitressin and Pitocin produced different effects on fetal and maternal brain O2 availability. These differences can be accounted for by the known hemodynamic and/or uterine actions of these drugs.
Pulmonary vascular obstruction in graded tachypneagenic diffuse embolism
Authors: Bernthal Theodore , Horres Alan D. , Taylor Joseph T.
Published: December 2017

One group of experiments revealed minimal doses of 75 µ pulmonary emboli required for eliciting increased frequency and decreased amplitude of breathing in anesthetized dogs. Others measured in vivo lung lobe autoperfusion flow rates at several constant perfusion pressures to determine the fractions of the pulmonary vascular bed obstructed by these and other quantities and to determine concurrent changes in flow-pressure relationships. The fraction of the vascular bed obstructed by threshold tachypneagenic quantities averaged 10% but in some instances was as little as 3%—values so small that the expected hemodynamic consequences in intact animals would be within physiological ranges and therefore seemingly not important as a tachypneagenic mechanism. Following embolization, resistance to blood flow increased in the nonoccluded intralobar vascular bed, particularly at lower perfusion pressures, and associated alterations in flow-pressure and resistance-pressure relationships pointed toward moderate increase in vascular tone as the cause. Quantities of emboli apparently required for completely obstructing the pulmonary vascular bed were considered in relation to established anatomical dimensions.
Life span of mice fed enriched or restricted diets during growth
Authors: Silberberg Ruth , Jarrett Susan R. , Silberberg Martin
Published: December 2017

Longevity was studied in male mice of the inbred strain C57BL Jax 6 fed during the period of growth a stock diet enriched with 25% lard or the stock diet restricted to two-thirds of the ad libitum intake. The findings were compared with those obtained in controls kept on the stock diet ad libitum through life. Consumption of the fat-enriched diet ad libitum significantly lowered juvenile mortality and correspondingly increased the mean life span of mice thus fed. Underfeeding, on the other hand, significantly increased juvenile mortality and thus decreased the mean life span of the animals irrespective of whether they had been underfed jointly or individually. Mice underfed in groups retained a high mortality even beyond the period of growth. However, the life span of all other mice, once they had reached adulthood (200 days of age), was not affected by the changes in dietary regimen during growth; their mean life spans and the maximum ages reached were not significantly different from one another.
Bone resorption and Ca45 turnover in growing rats
Authors: Jeffay Henry , Bayne Harold R.
Published: December 2017

A group of rats were maintained on a Ca45 diet for 21 days, then sacrificed at varying time intervals after substituting a nonradioactive diet. The total calcium and calcium specific activity of several bones, blood and urine were determined. After correcting for the dilution of radioactivity due to an increase in total bone calcium, it was found that there was little, if any, loss of Ca45 from rapidly growing bones. When the growth of the bone decreased, a small measurable loss was detected. It was assumed this slow loss of Ca45 represented bone resorption. Values for the rate of bone resorption (replacement rates) are presented and their significance in the growth of the bone discussed.
Localization of amino-nitrogen reabsorption in the nephron of the dog
Authors: Brown J. L. , Samiy A. H. , Pitts R. F.
Published: December 2017

Utilizing the stop-flow method of analysis, we have observed that a series of amino acids, including glycine, l-alanine, d, l-alanine, l-glutamic acid, l-lysine, and l-arginine, is actively reabsorbed in the proximal part of the nephron of the dog. Reabsorption is maximal within that portion of the nephron where the secretion of p-aminohippurate is greatest. The reabsorption of arginine is reduced by the infusion of both lysine and ornithine. We conclude that the same cells of the proximal tubules reabsorb a variety of amino acids, and that the three basic amino acids, mentioned earlier, are reabsorbed by a single transport mechanism within a given tubular cell, or, at least, have some common step in their individual transport mechanisms.
Prolonged alteration of serum cholesterol induced by deoxyribonucleic acid in rabbits
Authors: Savitsky J. Philip
Published: December 2017

Desoxyribonucleic acid (DNA) was carefully prepared in a highly purified, undenatured form from beef liver. Each rabbit of a group of 20 rabbits received a single injection of 1 mg of this heterologous DNA. The mean serum cholesterol declined significantly within 4 months and was maintained at the new lower level with no return to control values for at least 2 years. This change in the mean reflected the decline in cholesterol levels of those animals with high normal values. The serum phospholipids responded similarly but no changes were observed in the serum neutral fat concentrations. Injection with varying quantities of DNA showed that the time required for changes to appear depended upon the amount of DNA injected.
Perfusion rates of brain, intestine and heart under conditions of total body perfusion
Authors: Johnson John A. , Gott Vincent , Welland Frederick
Published: December 2017

The perfusion rates of the brain, intestine and heart ventricle were studied under conditions of total body perfusion. The perfusion rates were estimated by using antipyrine and D2O as reference substances. Local flow was determined from arterial curves and tissue analysis. When the total body perfusion rate was varied between 20 and 80 cc/kg/min., it was found at each rate that the perfusion rate of these organs was over three times that of the body as a whole. At the lowest flows these three organs were favored even more. Tables of perfusion rates at various sites in the brain and intestine are given. Pressure-flow curves for the brain, intestine and heart are given.
Active state plateau and latency in mammalian striated muscle
Authors: Norris Forbes H.
Published: December 2017

The active state plateau in rat striated muscle was studied by superimposition of tension curves resulting from one and two stimuli. The plateau ends 4.0 ± 0.1 msec. after stimulation in rat striated muscle at 36°C. The time to the end of the plateau is 3.4 ± 0.1 times the latent period. During the plateau, response to a second stimulus appears after increased mechanical latency. The second stimulus can also result in tension development at rates nearly twice those reached after a single stimulus. This effect has a peak which about corresponds to the end of the active state plateau, but precedes the peak of the curve for maximum tension. Correct timing of the second stimulus can result in about 60% of tetanic tension. The use of thiopental, gallamine, tubocurarine and changes in muscle length did not affect these results.
Effects of ultrasound on skeletal and cardiac muscle in the ground squirrel
Authors: Zimny Marilyn L. , Head Lionel H.
Published: December 2017

Adenosine triphosphate (ATP), phosphocreatine (PC), inorganic phosphate (IP), and glycogen were determined on skeletal and cardiac muscle samples from 28 nonhibernating and 10 hibernating ground squirrels, Citellus tridecemlineatus, following ultrasonic irradiation in vivo. A dosage of 0.13–3.0 w/cm2 of 1 megacycle was applied for 3–6 minutes. The left legs and left half of the thorax were treated and the results compared with data from untreated animals. In studying the leg samples the treated and untreated sides of the experimental animal were compared. The phosphates, ATP and PC, were decreased significantly with slight changes in IP and glycogen. In both nonhibernating and hibernating animals the effects were seen in both legs signifying travel of the sound or a resultant effect. In both groups the changes took place without a change in the animal's rectal temperature. Histological study of samples from the treated legs revealed no changes in structure or glycogen and phosphate deposition. Ultrasound applied locally on the intact animal was followed by changes in compounds relevant to muscle contraction without apparent structural change.
Interaction between growth hormone and rat muscle in vitro
Authors: Kostyo J. L. , Schmidt J. E.
Published: December 2017

Hypophysectomized rat diaphragms, which were immersed briefly in dilute solutions of growth hormone and then washed thoroughly, subsequently transported α-aminoisobutyric acid-1-C14 at a greater rate than the controls. Growth hormones of bovine, porcine, simian and human origins were all effective. Increasing either the hormone concentration or the length of time that the diaphragms were immersed in growth hormone solutions increased the effect on amino acid transport. Prolonged washing of the diaphragms following exposure to growth hormone did not reduce the magnitude of the effect on amino acid transport. Moreover, reducing the temperature of the growth hormone solutions did not diminish the resultant effect on amino acid transport. From these results, it was concluded that the initial interaction between growth hormone and rat muscle in vitro occurs rapidly and the modification produced by this interaction is relatively stable.
Frequency and vagal effects
Authors: Young Wei , Upham Frank
Published: December 2017

Effects of frequency of stimulation were studied in the isolated vagal heart preparation of Rana pipiens. Normal inhibitory effects were readily obtainable by stimulating the vagus nerve at pulse rates between 10 pulses/sec. and 100 pulses/sec. for a period of 10 seconds. A little above 100 pulses/sec. or below 10 pulses/ sec. the heart was usually less responsive to the same period of vagal stimulation. Below 5 pulses/sec. or above 200 pulses/ sec. the isolated preparation was practically nonresponsive to vagal stimulation for the 10-second period. The heart was responsive to the lower pulse rate but not to the higher rate when stimulated for a longer period. Arrhythmia usually was induced by frequent application of high-frequency stimulation. This suggests that the pacemaker is somehow temporarily impaired by high-frequency bombardment. The inhibitory effect is proportional to the duration of the impulse for any optimal frequency. The observed inhibitory vagal phenomenon results primarily from the liberation of an acetylcholine-like substance from the vagal nerve endings. The amount of this substance liberated can be assayed quantitatively. It was estimated that each optimal volley liberated approximately 2.5 x 10–11 gm of acetylcholine-like substance.
Capillary density in mammals in relation to body size and oxygen consumption
Authors: Schmidt-Nielsen Knut , Pennycuik Pamela
Published: December 2017

The high metabolic rate per gram of tissue in small mammals requires that oxygen be supplied to the tissues at a higher rate than in larger animals. The high rate of oxygen delivery in the small animal can be accomplished by a) higher capillary density and b) higher unloading tension for oxygen. Both these factors in the oxygen supply vary with body size in such a manner that delivery of oxygen to the tissues is facilitated in the small animal. This paper gives comparative data on capillary density in muscles from 10 mammals of various size. The smallest mammals have significantly higher capillary densities, but the trend is not evident throughout the size range examined. It is therefore reasonable to assume that the factors that relate capillary density and body size are overshadowed by variables such as activity, domestication, cold acclimation, etc., and, perhaps primarily, the size of the muscle fibers, which (although dependent on body size) varies considerably with the type of muscle and its use.
Iodide transport by the rabbit eye
Authors: Becker Bernard
Published: December 2017

I131 is accumulated by rabbit ciliary body-iris preparations in vitro and transported out of the living rabbit eye. The secretory system resembles the accumulation of iodide by the thiouracil-treated thyroid gland. It is saturated by iodide and inhibited by perchlorate, thiocyanate and fluoroborate. The mechanism for iodide transport out of the rabbit eye appears to be independent of the analogous transport of iodopyracet and related organic anions.
Effect of chloride ions on cock spermatozoa
Authors: Zayat S. El , Tienhoven A. Van
Published: December 2017

The respiration rate, rate of fructolysis and incidence of abnormal spermatozoa were studied in cock semen immediately after dilution (1:10) and after storage at 5°C. Tyrode's solution was the basic diluent, and the effect of replacement of chloride by either glutamate or phosphate was investigated. Replacement by glutamate resulted in a linear reduction of respiration and fructolysis rates of fresh semen and of the fructolysis rate of stored semen. Respiration rate of stored semen decreased nonlinearly. Replacement of chloride by phosphate had no significant effect on the metabolic rates of either fresh or stored semen. Chloride ions caused an increase in the incidence of abnormal sperm after storage. When glutamate replaced chloride this increase was reduced, whereas in phosphate replacement there was evidence of a synergistic effect between chloride and phosphate in causing abnormalities. Differences in metabolic rates could not be accounted for by changes in the incidence of dead or abnormal sperm.
Fat mobilization and hyperlipemia from pituitary extracts in rabbits
Authors: Landolt Ruth , Astwood E. B.
Published: December 2017

A crude pituitary extract, potent in inducing visible lipemia in male rabbits, caused a) an eightfold increase in free fatty acids of the serum 1–2 hours after injection, followed by a 2.5-fold increase of fatty acid output in vitro from adipose tissue, removed 4 hours after injection; b) a reduction in lipoprotein lipase activity of adipose tissue at the same time; c) an increase in liver fat which was already prominent at 4 hours and which preceded the ninefold increase of total lipids in the serum at 24 hours. The lipemia was prevented by large doses of heparin. A direct effect of the extract on adipose tissue in vitro was observed; this was partially inhibited by insulin and glucose. Pig growth hormone given in corresponding doses produced the same effect, but to a smaller degree. It was concluded that the hyperlipemia is due to a separate factor, and that the lipemia is a consequence of excessive lipolysis in association with diminished lipoprotein lipase activity.
C14 studies in carbohydrate metabolism: V. Glucose metabolism in alloxan-diabetic rats
Authors: Baker Nome , Shipley Reginald A. , Clark Richard E. , Incefy Genevieve E. , Skinner Selby S.
Published: December 2017

A six-compartment model has been designed to approximate the pool system as it is conceived to exist for glucose, bicarbonate and equilibrating metabolites in the intact rat. The rates of internal exchange and external egress of glucose have been calculated for normal and diabetic animals. The turnover of glucose, exclusive of urinary excretion, was approximately twice as high in diabetic animals as in normal animals in both dietary states. Of the total turnover of glucose approximately one-third was recycled (glucose → nonglucose → glucose) in fasted animals, both normal and diabetic, and one-half in postabsorptive animals. Oxidative disposal of glucose in the postabsorptive state tended to be lower in diabetic than in normal animals, but in the fasted state the rate was higher in fasted diabetic rats. Whereas in normal animals the oxidative rate was higher in the postabsorptive state than during fasting, this was not true for diabetic animals. Nonoxidative, nonexcretory disposal of glucose was higher in diabetic rats, whether fasted or postabsorptive.
Effect of hyperventilation on glomerular filtration and renal plasma flow
Authors: Kanter G. S.
Published: December 2017

Dogs were anesthetized with 30 mg/kg of sodium pentobarbital. Creatinine clearance was used as a measure of glomerular filtration rate and the clearance of p-aminohippuric acid at low plasma concentrations was used as a measure of renal plasma flow. After two control periods, the dogs were progressively hyperventilated. The respiratory minute volume was increased from about 4 l/min. at the start of the hyperventilation to about 8 l/min. at the end of 3 hours of overventilation. The anaerobically measured arterial pH rose from a control value of 7.33 to 7.63 at the conclusion of the experiment. No change occurred in the glomerular filtration rate, renal plasma flow, filtration fraction, hematocrit, rectal temperature, heart rate or total solids in the plasma. Passive hyperventilation leading to pronounced alkalosis of short duration does not appear to alter renal hemodynamics sufficiently to cause any change in the filtration rate or effective renal plasma flow.
Alterations in central latency, motoneurone number and blood volume of spinal cord of the aging rat
Authors: Sant'Ambrogio G. , Frazier D. , Reed R. , Boyarsky L. L.
Published: December 2017

Measurements were made of the central delay of the flexor reflex, the number of motoneurones in the ventral horn of the lumbar region of the cord, and the tissue blood volume of the lumbar region of the cord. There is a 50% decrease in tissue blood volume between the ages 450 and 550 days. A loss in the number of motoneurones of the cord of about 30% also occurs between the same ages. Central latency increases about 60% from a value of 3.51 msec. to 5.82 msec. between the ages 550 and 750 days. This rise in central latency takes place after the blood volume decrease and the loss in number of cells. It is suggested that the primary event in the aging of the nervous system of the white rat is a restriction of the vascular bed; with changes in latency secondary to the loss in neurones. These results are also taken as evidence that local, intrasegmental changes in the cord as well as alterations of suprasegmental downflow play an important role in aging of the spinal cord.
Reflex relationships of paravertebral muscles
Authors: Eble John Nelson
Published: December 2017

The muscles of the back are shown to function reflexly in various antagonistic and synergistic pairs. Intertransversales muscles of opposite sides can act synergistically for ventral flexion or antagonistically for lateral flexion. Multifidus muscles of opposite sides act independently or synergistically only. There is a stronger reciprocal relationship between the multifidus on one side and the intertransversales of the other side than between multifidus and intertransversales of the same side. Inhibition of antagonists occurs with stimuli too weak to excite the agonists. The patterns of the spinal reflex responses of the paravertebral musculature to cutaneous stimulation change with regard to segmented level and to area of skin stimulated. Stimulation of dorsal skin provokes reflex contraction of the multifidus muscles. Stimulation of ventral skin provokes reflex contraction of the intertransversales muscles. A stimulus applied to a lateral skin area elicits a response in both members of this antagonistic pair. Moving the dorsal stimulus caudally from L-5 to L-6 results in a change of the reflex pattern from multifidus activity to intertransversales activity.
Response of tissue electrolytes to respiratory acidosis
Authors: Levitin Howard , Amick Carol J. , Epstein Franklin H.
Published: December 2017

The effect of 8% CO2 for 24 hr on the electrolyte composition of muscle, bone, and liver has been studied in rats on a normal diet as well as on one low in sodium and low in potassium. Muscle potassium decreased in animals on a normal or low-sodium diet exposed to CO2. Muscle sodium decreased in animals on a low-potassium diet exposed to CO2, and there was no further change in the already low levels of muscle potassium. The sodium and potassium content of bone and liver and the calcium content of bone were unchanged by exposure to CO2. Nephrectomy blocks the loss of muscle potassium noted in rats on a normal diet. Muscle and bone sodium were also unaltered by CO2 in nephrectomized rats. These results contrast with those obtained during metabolic acidosis and emphasize the importance of the kidneys in bodily adjustments to respiratory acidosis.
Relationship of blood pressure level in chickens to resistance to physical stresses
Authors: Sturkie Paul D. , Textor Kurt
Published: December 2017

Hypertensive and hypotensive White Leghorn male and female chickens were subjected to low and high temperatures and to exercise. There were no significant differences in the response of hypertensive and hypotensive birds to high temperature. When hypothermia was induced by placing the birds in water at 20 C, survival times of the hypertensive males and females were significantly greater than for the hypotensive birds. When hypertensive and hypotensive birds were made to exercise (treadmill walking) the resistance to fatigue was significantly greater in the females with high blood pressure, but no differences were observed between the two groups of males; both hypertensive and hypotensive male birds exhibited considerably greater resistance to fatigue than did the females.
Cardiac output and peripheral blood flow during occlusion of carotid arteries
Authors: Polosa C. , Rossi G.
Published: December 2017

Cardiac output and blood flow to the kidney, hind limb, and splanchnic area were studied in anesthetized dogs during the arterial pressure rise due to carotid occlusion. All the vascular beds studied exhibited an increased resistance to flow. Cardiac output was maintained constant through an increased cardiac work in spite of the increased arterial pressure. This increased cardiac work was reflexly produced as evidenced by the action of the adrenergic blocking agent dichloroisoproterenol (DCI). This drug allowed the reflex vasoconstriction and the consequent pressure rise, but preventing the reflex chronotropic and inotropic sympathetic effects on the heart resulted in a fall of cardiac output during carotid occlusion. It is concluded a) that the reflex increase in vasomotor tone is the main factor in the pressor response to carotid occlusion and b) that the reflex effect on the myocardium is an important factor in regulating cardiac output in this situation.
Thyroid function and peripheral thyroxine metabolism after hemorrhage in the rat
Authors: Lang Stanley
Published: December 2017

Various parameters of thyroid gland function and of thyroid hormone level regulation in the serum have been investigated in the rat after acute, massive hemorrhage. There was a slight but significant depression of the protein-bound serum iodine. This depression was not associated with a release of additional TSH as inferred from the fact that thyroidal iodine release was inhibited. Other changes observed after hemorrhage were an increase in T:S iodide concentration ratio and a marked inhibition of biliary content of iodide which rapidly returned toward control values. There was no apparent change in the rate of thyroxine disappearance from the circulation after hemorrhage, but the only plausible interpretation of this observation is peripheral inhibition of thyroxine utilization.
Effect of acid and alkaline K phosphate on acid and electrolyte excretion in dogs
Authors: Brodsky William A. , Carrasquer Gaspar
Published: December 2017

Page 1232: William A. Brodsky and Gaspar Carrasquer, "Effect of acid and alkaline K phosphate on acid and electrolyte excretion in dogs." Page 1232, second column, first sentence should read: Theoretically, one could account for various levels of ionic excretion as follows: potassium excretion changes from low to high steady state levels as a function of exogenous load of potassium, and not as a function of metabolic acid production or excretion.
Glucose metabolism and mobilization of fatty acids by adipose tissue from obese mice
Authors: Leboeuf Bernard , Lochaya Serene , Leboeuf Nicole , Wood Francis C. , Mayer Jean , Cahill George F.
Published: December 2017

Free fatty acid mobilization and glucose metabolism to CO2, to glyceride-glycerol, to fatty acids and to glycogen by adipose tissue in vitro were studied in genetically obese hyperglycemic mice (O-H), in goldthioglucose-injected obese Swiss mice and in their respective nonobese littermates. Tissue from O-H mice metabolizes less glucose than tissue from their nonobese littermates in absence of added hormone or in the presence of insulin (0.1 unit/ml) or epinephrine (10–4 m). In addition, there is also a diminished ability for insulin to inhibit and for epinephrine to augment free fatty acid release. No such differences were observed between tissues from goldthioglucose-injected obese Swiss mice and tissues from their lean littermates. Possible significance of these in vitro results with regard to the pathogenesis of the obese hyperglycemic syndrome is discussed.
Changes in succinic dehydrogenase activity related to feeding
Authors: Nielson R. R. , Klitgaard H. M.
Published: December 2017

The effect of feeding and fasting on succinic dehydrogenase activity in rats accustomed to a feeding regime (fed 5 hr/24 hr) was studied over a 24-hr period and over a subsequent extended fast. The results showed a fall in enzyme activity to a minimal value at 6 hr after the initial feeding period in the four tissues studied. During the 24-hr period following feeding, cardiac and psoas muscles obtained maximum values which were 134% and 174%, respectively, of the 6-hr value at 18 hr. Liver and kidney attained their maximum values (133% and 174%, respectively) during the second 5-hr feeding period. When the fasting period was extended by omitting the second feeding period, liver and kidney tended to plateau (after their peak at 24 hr) near the 6-hr assay, whereas cardiac and psoas muscles (after their peaks at 24 and 18 hr, respectively) tended to plateau with 145% of the 6-hr activity. Variations related to feeding times, not previously realized, were demonstrated.
Effect of partial hippocampal resection on stress mechanism in rats
Authors: Kim Chul , Kim Chang Uk
Published: December 2017

Chronic (repeated skin incisions) as well as acute stress (left adrenalectomy) was applied to rats whose hippocampus had been damaged through the neocortex (hippocampus-damaged), to rats in which only the portion of the neocortex over the hippocampus had been damaged (neocortex-damaged), and to control rats. Both in the acute and chronic stress series, the left adrenal ascorbic acid content before stress was compared with that of the right adrenal gland following stress, and the difference served as a measure of reaction to the stress. Under acute stress, 72 rats showed a decrease in adrenal ascorbic acid content more pronounced in hippocampus-damaged rats and control animals than in the neocortex-damaged animals. Under chronic stress, increase in adrenal ascorbic acid content in 68 rats was least pronounced in hippocampus-damaged rats, most marked in neocortex-damaged animals, while the value was intermediate in control rats. The inference from these data is that the hippocampus exerts a sustained inhibitory influence upon the pituitary-adrenocortical mechanism.
Effect of Dibenamine on LD100 following supralethal dose of total body gamma radiation
Authors: Handford Stanley W. , Johnson Paul W.
Published: December 2017

Dibenamine, an adrenergic blocking agent, was administered to dogs immediately before they were subjected to a supralethal dose of whole body radiation. No significant differences in the course of acute radiation sickness or survival time (LD100) between the treated and sham-treated control groups were observed.
Comparative effects of prednisolone and thyroid hormone on bile secretion in the dog
Authors: Gans Joseph H. , McEntee Kenneth
Published: December 2017

The enterohepatic circulation of euthyroid dogs contained 1.25 ± 0.24 g bile acids/10 kg body wt. The bile acid content of the enterohepatic circulation of hyperthyroid dogs given thyroid hormones for 3 weeks was 0.72 ± 0.21g/10kg body wt., a significant difference from the control group ( P( t) < .01). No significant differences in biliary cholesterol output were recorded. Bile secretory changes in the hyperthyroid state were unrelated to food intake or changes in body weight. No evidence was found to indicate an early period of enhanced bile acid or biliary cholesterol secretion accompanying thyroid hormone administration. The administration of prednisolone trimethylacetate to euthyroid dogs resulted in a significant ( P( t) < .01) increase in total bile volume recovered. The enterohepatic bile acid content of the prednisolone-treated dog was 1.84 ± .48 g/10 kg body wt., the difference from the control group being of marginal significance ( P( t) < .05 > .02). Two hepatic function tests, the secretory response to sodium dehydrocholate administration and the rate of disappearance of bromsulfonphthalein from plasma, did not indicate any gross derangement in hepatic function in the hyperthyroid or prednisolone-treated dogs.
Electric activity of gastroduodenal junction
Authors: Bass Paul , Code Charles F. , Lambert Edward H.
Published: December 2017

In preparation for a study of the electric activity in the wall of the gastroduodenal junction in unanesthetized trained dogs, the pyloric portion of the stomach (antrum), the pylorus, and the first portion of the duodenum were exteriorized surgically. When the animals were fully recovered, needle electrodes were inserted into the wall of the bowel for the detection of electric activity. The pylorus was found to act as an "electric insulator" between the stomach and the duodenum. The basic electric rhythm (BER) and the fast or spike activity detected in both the pyloric canal and the duodenal bulb became attenuated in the pylorus and usually disappeared in it. The BER of the antrum had a mean frequency of 4.4 cycle/min and spike potentials sometimes were associated with it. The frequency of the BER in the duodenal bulb was the same as in the duodenum but its voltage was less and its form more irregular. Spike potentials in the bulb occurred during a greater portion of the BER and had a greater tendency to distort the BER than in the more distal duodenum.
Substrate effect on functions of embryonic chick heart
Authors: Boucek Robert J. , Paff George H.
Published: December 2017

The 72-hr chick embryo heart has a rhythm resulting from the regular discharge of a pacemaker center and the subsequent conduction of the electrical impulse through the tubular heart. This phenomenon is recordable and results in an electrocardiogram indistinguishable in its general form from the adult mammalian record. The excised embryonic heart tissue placed in Tyrode's solution and maintained at 28.5–29.5 C continues to perform its electrical and contractile functions. General properties, i.e., deterioration of contractility, were studied and the effect of substrate alterations on this deterioration as well as the electrocardiogram was observed. The electrocardiogram is resistant to alterations in the concentration of potassium and becomes obliterated whenever sodium or calcium is absent from the fluid environment. The persistence of cardiac contraction similar to the control state occurred with certain anion alterations (I > NO3 > Br > SCN), by the addition of glucose, and by an alkaline environment (pH 7.6–8.6). "Injury potentials," seen on the electrocardiogram, developed and were associated with a rapid deterioration of speed and intensity of contraction. This abnormal electrical potential appears to be linked to the glycolytic cycle, was absent in an alkaline environment and in a potassium-free solution, and was accentuated when the heart was placed in Tyrode's solution containing no chloride ions.
Influence of hypertonic solutions on ventricular contractile activity
Authors: Nayler Winifred G.
Published: December 2017

The reduced amplitude of contractions which resulted from perfusion of isolated toad ventricular muscle in Ringer's solution made hypertonic by the addition of sucrose was rapidly followed by states of "tetanus" and of contracture. The amplitude of contracture varied with both the perfusate calcium concentration and with the stimulation frequency. Replacement of the hypertonic by the standard perfusate resulted in posthypertonic potentiation.
Hepatic effect of insulin in unanesthetized normal, diabetic, and adrenalectomized dogs
Authors: Shoemaker William C. , Carruthers Peter J. , Powers Ina C. , Yanof Howard M.
Published: December 2017

Measurement of arterial, portal, and hepatic venous plasma glucose concentrations were made in unanesthetized dogs whose hepatic vessels were previously catheterized. Total hepatic blood flow was measured by a modified Bromsulphalein method and hepatic arterial blood flow by a trapezoidal wave electromagnetic blood flowmeter. Serial biopsies of the liver were obtained, also under unanesthetized conditions, for measurement of glycogen and free glucose. Various doses of glucagon-free insulin were given by a single, rapid, intravenous injection or by a constant infusion directly into the liver via portal vein and via femoral vein or vena cava. Insulin was administered in normal, in adrenalectomized, in depancreatized, and in depancreatized-adrenalectomized dogs. Under each of the conditions observed insulin produced no decrease in the hepatic glucose output. Moreover, no increased hepatic glycogen or free glucose concentrations were found in hepatic biopsies after insulin administration.
Effects of diethylstilbestrol with thyroxin or thiouracil on thyroid in male rats
Authors: Hartsook E. W. , Hershberger T. V. , Long T. A.
Published: December 2017

Sixty-six normal or castrate young male rats were used, as replicates of three or four animals each; they were subjects for equalized feeding, within replicates, of a basal diet with no additives, and a basal diet with additives per gram of diet of 0.6 µg diethylstilbestrol (DES) and 1 µg l-thyroxin or 1 mg thiouracil. Criteria evaluated were weight gain, feed efficiency, body length, and size of pituitary, thyroid, adrenals, and testes. DES produced significant reductions in weight gain, feed efficiency, and size of testes, and significant increases in size of pituitary, thyroid, and adrenals. Responses of castrate animals to DES were altered in the same direction as those of normal animals; all differences, except for thyroid, were significant. Castrate DES-treated animals exhibited smaller weight gain and feed efficiency, and less thyroid hypertrophy than normal DES-treated animals. Thyroxin overcame a significant portion of DES-induced thyroid hypertrophy; it significantly further depressed the feed efficiency of DES treatment alone. Thiouracil produced the expected thyroid enlargement, and significantly increased weight gain, feed efficiency, and size of pituitary and testes in DES-treated rats; it significantly reduced body length and adrenal size.
Stellate ganglion stimulation and performance of dog heart-lung preparation
Authors: O'Brien Larry J.
Published: December 2017

Observations were made on the changes in cardiac function in the dog heart-lung preparation, brought about by stimulation of the left stellate ganglion, and were compared with observations obtained when the heart was driven by an artificial pacemaker, as well as with changes produced by epinephrine administration. During left stellate ganglion stimulation, cardiac output increased approximately 79%; stroke volume showed a mean increase of 55%, whereas the heart rate had a mean increase of 19%. When the heart was driven by an artificial pacemaker, cardiac output showed no change; heart rate had a mean increase of 28%. The stroke volume, on the other hand, decreased 22% below the control value. It is concluded that left stellate ganglion stimulation in the dog heart-lung preparation causes significant increases in both the stroke volume and heart rate.
Extrahepatic clearance of I131 rose bengal
Authors: Jones Don P. , Terz Joseph , Lawrence Walter , Poppell J. William
Published: December 2017

The extrahepatic clearance of rose bengal-I131 has been measured in nine eviscerated dogs, giving a mean value of 0.33 ± .19 cc/kg-min (whole blood). The extrahepatic clearance was independent of the peripheral blood concentration of the dye over a range from 0.00038 mg/cc to 0.033 mg/cc. The error introduced in the determination of estimated hepatic blood flow due to extrahepatic extraction of rose bengal-I131 is of the order of 3.7% ± 2.8%. This error is independent of the blood concentration of the dye over the range measured.
Luteinizing hormone-induced depletion of ascorbic acid in the rat ovary
Authors: Goldstein Donald P. , Sturgis Somers H.
Published: December 2017

Luteinizing hormone specifically depletes the pseudopregnant rat ovary of ascorbic acid. This depletion takes place from the corpora lutea as determined by cytochemical methods. The depletion reaction has a characteristic time sequence which resembles that seen in the adrenal gland but takes place over a more prolonged period of time. The onset of depletion is within 15 min of the injection of purified luteinizing hormone, reaches maximum intensity at 3 hr, and ends by 19 hr when a rebound effect is seen. The most striking cytochemical finding is that of "clumping" of ascorbic acid granules, which is first noted at 3 hr and persists until depletion ends at 19 hr. The physiologic significance of this reaction is not well understood.
Basis of the depressor action of adenosine phosphates
Authors: Gordon David B.
Published: December 2017

It was previously shown that, when injected intravenously in the rat, ADP is a considerably more potent blood pressure lowering agent than adenosine, AMP, or ATP. The basis of this difference was investigated. It was found that the depressor action of all four compounds depends largely, if not entirely, upon dilation of peripheral blood vessels and that vagal reflex action, cardiac slowing, and pulmonary vasoconstriction do not contribute to the lowering of the blood pressure in the dose range studied. Adenosine and AMP are less effective vasodilators than ADP. ATP is an equally or possibly more effective vasodilator than ADP when injected intra-arterially but considerably less effective when injected intravenously. It is concluded that ATP, but not ADP, is to a large extent trapped or inactivated in the pulmonary circulation. For this reason ADP is the most potent depressor agent when the compounds are injected intravenously.
Cerebrospinal fluid iodide
Authors: Becker Bernard
Published: December 2017

In vitro preparations of rabbit choroid plexus accumulated I131 to a concentration 20–30 times the media. The accumulation was temperature dependent and was blocked by metabolic inhibitors. It could also be saturated with iodide, and was inhibited by perchlorate, fluoroborate, and related anions. In vivo the low 4-hr steady state concentration (1.6% of plasma) of trace doses of I131 in the rabbit cerebrospinal fluid was increased (to 40% of plasma) by the systemic administration of iodide or perchlorate. The results resembled qualitatively those obtained in the vitreous and aqueous humors of the same animals and suggested an active transport of iodide out of the cerebrospinal fluid, much as postulated previously for ocular fluids.
Hypothalamic neurohormonal agents and sexual maturation of immature female rats
Authors: Corbin Alan , Schottelius B. A.
Published: December 2017

The possible role of four recognized hypothalamic constituents in activation and maturation of the hypophysial-reproductive organ complex of immature female albino rats was investigated. Normal and hypophysectomized rats and rats with bilateral destruction of an area extending from the ventromedial nucleus to mammillary body were studied. Animals were injected either with 70 milliunits of antidiuretic hormone (ADH), 70 milluniits of oxytocin, 25 µg of serotonin, or 2 µg of epinephrine every 5th day, from age 20 through 45 days, via a cannula permanently implanted in the 3rd ventricle of the brain. No response to ADH was observed. Oxytocin accelerated vaginal canalization and caused premature reproductive organ growth in normal recipients. Whereas lesioned untreated controls remained sexually retarded, vaginal opening and reproductive organ growth equivalent to 50-day-old sham-operated controls were induced in lesioned animals by oxytocin administration. Serotonin prevented maturation in normal controls, but was ineffective in lesioned animals. Hypophysectomized rats were unresponsive to any agent injected. The results imply that oxytocin may directly activate the hypophysis of immature female rats. Serotonin, on the other hand, inhibits the hypophysial-gonadal axis of these animals, but its effects probably are relayed via the hypothalamus.
Measurement of liver blood flow with radioactive colloidal gold
Authors: Meredith O. M. , Coffman William , Post Jane , Holmes John
Published: December 2017

The reliability and sensitivity of the use of colloidal radiogold preparations for measurement of liver blood flow in animals by external γ-ray scintillation detection methods has been studied for 2 years. During this period control measurements fluctuated sufficiently to justify recommendation that colloidal radiogold preparations intended for blood flow measurement should be tested by suitable bio-assay procedure. Other aspects of blood flow measurement were examined. Estimates of liver blood flow appeared more consistent when determined with half-times for the exponential blood disappearance process than with blood retention values. Half-times for liver uptake of colloidal radiogold agreed with those for blood disappearance such that either values might be used as an index of liver blood flow. Ether anesthesia had no effect upon liver blood flow during these studies upon rabbits. Experimental alterations of the liver blood flow demonstrated the sensitivity of the test for variation in blood flow. For example, total occlusion of the portal vein markedly affected the estimate for blood flow, whereas severe acute carbon tetrachloride poisoning had no effect upon blood flow when tested after 24–48 hr by this method.
Right ventricular pressure and coronary flow
Authors: Cross Cecil E.
Published: December 2017

A method is described which permitted separate, simultaneous measurement of blood flow in the left and right coronary arteries while the performance of the left or right ventricles was altered. As long as neither ventricle was overdistended and when arterial oxygen tension and pH were constant, blood flow in the right or the left coronary tree was a linear function of the right or left coronary driving pressure. When the right ventricle was overdistended so that abnormally high pressures existed in it, vasomotor tonus in both coronary trees was markedly diminished, although the performance of the left heart did not vary appreciably.
Selective induction and suppression of liver enzyme synthesis
Authors: Weber George , Banerjee Gouri , Bronstein Seymour B.
Published: December 2017

Two techniques were used to demonstrate selective induction of enzyme increases in mammalian tissue in vivo: a) refeeding of fasted animals, and b) administration of cortisone to adrenalectomized animals. Refeeding acted selectively as an inducer for the stimulation of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities, and as a less effective inducer of phosphoglucomutase, phosphohexose isomerase, glucose-6-phosphatase, and lactic dehydrogenase. On the other hand, cortisone acted selectively as an inducer for increases in glucose-6-phosphatase, fructose-1, 6-diphosphatase, phosphohexose isomerase and lactic dehydrogenase, and as a less effective inducer of 6-phosphogluconate dehydrogenase. Thus, refeeding primarily stimulated enzymes mediating the direct oxidation of glucose-6-phosphate, whereas cortisone stimulated enzymes involved in gluconeogenesis. The amino acid analogue ethionine selectively inhibited the induced increase of enzyme activities and methionine reversed the ethionine inhibition. The nature of the elevations in the enzyme activities and the mechanisms of ethionine inhibition were discussed.
Kinetics of accumulation of radioiodine by thyroid gland: short time intervals
Authors: Wollman Seymour H. , Reed Franklin E.
Published: December 2017

The protein-bound radioiodine and radioiodide concentrations in the thyroid gland and serum radioiodide concentrations in rats and mice were measured between 3 and 16 min after injection of radioiodide. The data were compared with predictions of a simple open three-compartment model of the thyroid gland. The model generally fitted the experimental data well. The amount of radioiodine incorporated into organic binding each minute varied from one-third to twice the amount of radioiodide in the thyroid, depending on diet. The data were also compared with previously published results on duplicate sets of animals in which the formation of protein-bound iodine was acutely blocked by a goitrogen. The ability of the thyroid to maintain a concentration of radioiodide elevated above that of blood serum was much less when binding was permitted than when blocked and seems to be due to removal of thyroid radioiodide by the binding process and, in addition in the rat, by increased transport of radioiodide from thyroid to blood.
Kinetics of accumulation of radioiodine by thyroid gland: longer time intervals
Authors: Wollman Seymour H.
Published: December 2017

The radioiodide and the protein-bound radioiodine (PBI131) concentrations in the thyroid gland and the serum radioiodide concentrations in mice and rats were measured at various time intervals (up to 25 hr) after injection of radioiodide. The ratio of the radioiodide concentrations in the thyroid gland and serum (T/S) increased progressively with the time interval after injection. If it is assumed that a small but constant fraction of the thyroid PBI131 decomposed during the fractionation of the thyroid I131, the corrected thyroid radiodiode concentration yielded a constant T/S up to 4 hr after injection and the rate of increase of the thyroid PBI131 was proportional to the thyroid radioiodide concentration. The corrected data were therefore consistent with a previously published simple model. Analysis of the source of thyroid radioiodide indicated that at 4 hr after injection almost all was derived from blood serum, but at 25 hr most could have been derived from thyroidal PBI131 by physiological degradation.