bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of age, sex, and nutrition on liver phenylalanine hydroxylase activity in rats
Authors: Freedland R. A. , Krakowski M. C. , Waisman Harry A.
Published: December 2017

This study provides data on a number of factors that influence phenylalanine hydroxylase activity in rat liver. By means of a method which utilizes crude liver homogenates, the enzyme activity was determined in rat liver obtained from early embryos to 150-day-old animals. The activity increases with age to a maximum at the young adult age of 50–60 days and then declines. The most rapid increase in activity was found between 18–21 days. The female rat livers show a rapid decline in activity with increasing age, then stabilize at a lower activity than males after maturity is reached. Fasting causes a marked drop in activity, and diets deficient in phenylalanine cause a decrease in the enzyme activity. High casein diets, which increase the phenylalanine and total amino acid intake, had no apparent effect on the level of enzyme activity.
Hepatic blood flow in experimental hemorrhagic shock
Authors: Frank Edward D. , Frank Howard A. , Jacob Stanley W. , Fine Jacob
Published: December 2017

In dogs in hemorrhagic shock, the blood flow and oxygenation of the liver were measured with a catheter in a hepatic vein. There is a marked reduction in hepatic blood flow and oxygenation throughout hemorrhagic shock. There is transient improvement following blood replacement and additional transfusions. Arterial shunts into the portal vein may restore hepatic oxygenation to preshock levels. Norepinephrine does not increase hepatic blood flow even though arterial pressure is restored to normal. Dibenamine pretreatment sustains the hepatic flow to some extent during hypovolemia; antibiotic pretreated animals do not differ from controls.
Distribution and fate of pancreatic enzymes in small intestine of the rat
Authors: Pelot Daniel , Grossman Morton I.
Published: December 2017

The trypsin, chymotrypsin, and lipase activities of washings of the small intestine of the rat were measured. Diversion of pancreatic juice to the exterior of the body resulted in rapid disappearance of enzymes from the small intestine with virtually complete absence after 16 hr. For all three enzymes, larger amounts were present in the lower than in the upper half of the small intestine. By several criteria the order of rate of inactivation, from least to most rapid, was trypsin, chymotrypsin, and lipase. Feces of intact rats contained readily measurable amounts of all three of these enzymes.
Mechanism of magnesium excretion by the chicken
Authors: Robinson Roscoe R. , Portwood Richard M.
Published: December 2017

Urinary magnesium excretion was evaluated during the administration of magnesium salts into one leg vein of the chicken by means of the Sperber technique. Changes of magnesium excretion paralleled those of filtered load and sustained unilateral differences of magnesium excretion were not observed. Corrected magnesium-inulin clearance ratios rose to values of approximately 1.0 and remained at that level despite continuing rises of filtered load. The results indicate that magnesium excretion is determined solely by glomerular filtration and tubular reabsorption. Evidence of a tubular secretory system was not obtained.
Effect of Triton WR-1339 on absorption and fate of I131 oleic acid in normal guinea pigs
Authors: Janicki Bernard W. , Leahy William V. C. , Mc Nickle Thomas F. , Aron Stephen A.
Published: December 2017

The influence of Triton WR-1339 on the absorption and tissue assimilation of orally administered I131 oleic acid was studied in normal guinea pigs. No significant difference was observed in either the plasma or liver radioactivity. However, the amount of radioactivity precipitated with plasma protein was significantly higher in Triton-treated animals. Extraction of the protein precipitates with lipid solvents demonstrated that the precipitated radioactivity was associated with lipid. The mechanism by which Triton induced increased serum levels of fatty acids was discussed in view of these findings.
Removal and mobilization of individual free fatty acids in dogs
Authors: Miller Harvey I. , Gold Martin , Spitzer John J.
Published: December 2017

Plasma free fatty acids were determined chemically and by gas chromatography in different anatomical sites. The myocardium removed palmitic and oleic acids and lesser amounts of stearic and linoleic acids. Electrically stimulated skeletal muscle took up oleic acid in greatest quantities. Liver showed consistent removal of stearic, oleic, and linoleic acids and an occasional uptake of other acids. The splanchnic area did not remove or mobilize free fatty acids. The composition of free fatty acids in thoracic duct lymph was similar to that in arterial blood, with the exception of a higher percentage of linoleic and possibly oleic acid. The total and free fatty acid fractions of the inguinal subcutaneous adipose tissue showed a similar distribution of fatty acids. Both were relatively high in oleic and linoleic acids. Free fatty acid released by adipose tissue had a lower oleic and linoleic acid content than that present in the cell.
Creatine metabolism in vitamin E deficiency in the rat
Authors: Gerber G. B. , Gerber G. , Koszalka T. R. , Emmel V. M.
Published: December 2017

Creatine-2-C14 was injected intraperitoneally into normal, vitamin E-deficient, and previously deficient rats treated with α-tocopheryl acetate. Creatine was isolated after various time intervals from different skeletal muscles, heart, brain, kidney, liver, blood serum, erythrocytes, retroperitoneal fat, urine, and total residual carcass, and its specific activity and quantity determined. Creatinine was isolated from urine and assayed for radioactivity. An increase in the ratio of specific activities of "free" creatine to muscle creatine was observed in vitamin E-deficient rats. After treatment with α-tocopheryl acetate, this ratio returned to normal values. From plots of specific activity vs. time, turnover times for creatine were computed: total carcass, 56 days; skeletal muscle, 51–53 days. Turnover time of creatine in carcass, brain, and skeletal muscle, with the exception of pectoralis muscle, was identical in normal and vitamin E-deficient rats. Specific activity in pools of free creatine of vitamin E-deficient rats initially was higher but subsequently became lower than that of normal rats. We concluded that uptake of creatine by muscle is diminished in vitamin E-deficient rats and as a consequence the size of the free creatine pool increases and creatinuria results.
Blockage of lactation by brain-stem lesions in the cat
Authors: Beyer Carlos , Mena Flavio , Pacheco Pablo , Alcaraz Manuel
Published: December 2017

The effect of brain-stem lesions on lactation in the cat was studied. Lesions in the rostral mesencephalon or caudal hypothalamus, which involved the dorsal longitudinal fasciculus, caused persistent supression of milk secretion and involution of the mammary glands. This effect seems to be due to interruption of the afferent pathway for prolactin secretion. Control lesions in other parts of the brain caused only a transient impairment of lactation.
Outflux of various phosphates during membrane depolarization of excitable tissues
Authors: Abood L. G. , Koketsu K. , Miyamoto S.
Published: December 2017

The main purpose of the present work was to study in detail the outflux of P32 from excitable tissues accompanying membrane depolarization or electrical excitation. With the use of P32 as a tracer, it has been demonstrated that orthophosphate and a number of organic phosphates slowly diffuse out of nerve and muscle even after 2 hr of exposure to Ringer's solution. On exposure to calcium-free or potassium-rich media, or during electrical excitation, there is a considerable increase in the outflux of a number of acid-soluble phosphates, particularly orthophosphate and adenosinetriphosphate. Further evidence in support of this concept was based on the fact that the radioactive specific activity of the diffusible phosphates was greater than the internal phosphates of excitable tissues. Since all these procedures are known to result in depolarization of excitable tissues, there was reason to believe that the outflux of muscle phosphates was somehow related to the physicochemical changes associated with membrane depolarization. The changes in the outflux of P32 from the muscle or nerve, either stimulated or soaked in calcium-free or potassium-rich media, appear to be related to the changes in the membrane potential.
Reactions of neurons in or near the supraoptic nuclei
Authors: Brooks Chandler McC. , Ushiyama J. , Lange Gertrude
Published: December 2017

The reactions of neurons within or near the supraoptic nuclei of the hypothalamus to a variety of "stimuli" were studied. A few neurons were found to be excited by stimulation of muscle afferents. Other neurons were inhibited by stimulation of gastrocnemius and tibialis nerve fibers. Stimulation of the vagus nerve activated some neurons and inhibited a few but, as in the case of muscle nerve stimulation, the vast majority of neurons were unaffected. Stimulation of midbrain and pontine reticular formation inhibited some neurons and activated others. Intracarotid injections of isotonic saline had no effect on neuron discharge but low concentrations of glucose augmented neuron firing as did hypertonic NaCl. Distilled water reduced neuron activity. Epinephrine, norepinephrine, and acetylcholine accelerated neuron firing; atropine was without effect in concentrations employed. Responses to injected materials developed more slowly and lasted longer than did effects of nerve stimulations. Some neurons were affected by several of the stimuli employed but the majority of neurons were unresponsive during the periods of recording which could be maintained.
Relationship between blood volume and accommodation in the rabbit eye
Authors: White Fred N. , Wood Joe G.
Published: December 2017

Changes in refractive state, blood volume of major components of the eye, and pupillary changes were studied in the rabbit eye under conditions of sympathetic stimulation, sympathectomy of the eye, and ligation of the major venous return of the eye. Stimulation of the superior cervical ganglion produced flattening of the lens accompanied by decreased blood volume of the eye homolateral to stimulation. The converse was true for interruption of sympathetic outflow to the eye. Such changes were not noted in contralateral eyes. Refractive changes toward myopia were induced by increasing blood volume by ligation of the vortex veins. The refractive change was greatest when venous ligation was accompanied by sympathectomy of the eye. No one portion of the eye was found to change its blood volume to a greater extent than the other portions, each component maintaining its relative volume.
Circulatory effects of profound hypothermia during extracorporeal circulation
Authors: Kahler Richard L. , Goldblatt Allan , Braunwald Eugene
Published: December 2017

The effects of hypothermia on peripheral vascular resistance, venous return, and systemic blood volume were studied in dogs using extracorporeal circulation and a constant systemic perfusion rate. Cooling to 15–20 C produced a significant fall in total systemic peripheral vascular resistance and a large augmentation of systemic blood volume. The latter was superimposed on the gradual increase in systemic blood volume which occurs in many dogs on cardiopulmonary bypass. Both systemic vascular resistance and blood volume returned toward control levels during rewarming. Indicator dilution curves demonstrated a decrease in the "actively" circulating blood volume despite the observed increase in total systemic blood volume. These observations suggest that during hypothermia significant arteriolar dilatation occurred and that substantial volumes of blood were "trapped" in the peripheral vascular bed. This trapping resulted in the striking decrease in venous return and increase in systemic blood volume.
Effects of insulin on amino acid and ribonucleic acid metabolism in rat adipose tissue
Authors: Carruthers Bruce M. , Winegrad Albert I.
Published: December 2017

Trichloroacetic acid precipitable protein and ribonucleic acid were isolated from paired pools of rat epididymal fat pads after in vitro incubation. Insulin in vitro, without glucose, had no effect on the incorporation of carbon from uniformly labeled glycine-C14, l-proline-C14 or l-histidine-C14 into adipose tissue protein. In the presence of as little as 0.1 µm/ml of unlabeled glucose, insulin markedly increased the incorporation of carbon from these three amino acids into protein. Insulin in vitro also increased the incorporation of carbon from glucose-U-C14 into both ribonucleic acid and protein. The recovery of C14 derived from glucose-6-C14 in the ribonucleic acid of adipose tissue relative to that from glucose-1-C14 was increased when insulin was present. Insulin increased the incorporation of C14 from pyruvate-2-C14 into adipose tissue protein in the absence of added glucose. The addition of glucose had no effect on the recovery of C14 from pyruvate-2-C14 when insulin was present. Carbon-14 from pyruvate-2-C14 was incorporated into ribonucleic acid, but insulin did not increase its incorporation.
Maternal influences on fetal cardiovascular system in the sheep, dog, and rabbit
Authors: Geber William F.
Published: December 2017

Continuous recordings of the fetal carotid artery blood flow, blood pressure, heart rate; renal, brain, uterine, and cotelydon blood flow; and maternal carotid artery blood pressure and heart rate were made during and after varied types of maternal stimulations and chemical injections in three anatomically different types of placental-uterine-fetal arrangements as exemplified by the sheep, dog, and rabbit. Included in this series was pinching of the ear, eyeball pressure, asphyxia, pure tones, stroking of the viscera, vagal stimulation, and intravenous injection of epinephrine, norepinephrine, acetylcholine, serotonin, and sodium pentobarbital. In all three animal species the fetal physiological responses were, in general, the same for any particular type of maternal stimulus or chemical injection. Fetal carotid artery blood flow together with fetal renal and brain blood flow were the most reliable indicators of fetal response to any particular maternal influence, with fetal blood pressure next and fetal cardiac rate the least reliable. Fetal renal and brain vasculature responded in the same qualitative manner to all maternal influences, whereas fetal carotid artery blood pressure and flow and cardiac rate were variable in their responses. All fetal responses were distinguished by their long duration, especially the renal and brain vascular responses.
Passage of fibrinogen to circulation via lymphatics
Authors: Kolmen S. N. , Vita A. E.
Published: December 2017

Thirty dogs, whose thoracic ducts were catheterized, were divided into three groups. Each group was bled and simultaneously infused with either an erythrocyte-serum or an erythrocyte-plasma suspension. Those dogs bled and infused with the former suspension lost 35% of the initial plasma fibrinogen concentration. Recovery occurred in 4 hr but was shortened by 50% if the thoracic duct catheter was inserted into a venous catheter between samplings. Fibrinogen delivered via the lymphatics accounted for 50% of recovered blood fibrinogen. The rate of delivery via lymphatics was characteristically biphasic: an immediate, sharp increase postinfusion and hemorrhage followed by a delayed, less pronounced yet sustained increase. The rate of lymphatic delivery of fibrinogen in dogs receiving the erythrocyte-plasma suspension followed the diminishing rate of lymph flow. The albumin, globulin, and total protein concentrations in blood and lymph of all dogs remained fairly constant, attesting to selectivity in response to fibrinogen depletion in blood.
Potassium in mecholyl-stimulated gastric secretion in the dog
Authors: Werther J. Lawrence , Hollander Franklin
Published: December 2017

Previous work indicated that K concentration ([K]) of gastric juice rises abruptly after histamine injection, concomitantly with acid efflux. Using Heidenhain and vagal pouch dogs, these experiments (26 in all) were repeated with mecholyl and histamine. The concentration-time curves for K were similar for both stimuli with early rise in [K], its late fall below preinjection level, and eventual recovery. The initial rise tended to be smaller and occurred less often with mecholyl. Its occurrence after histamine was also inconsistent. [K] was poorly correlated with both acidity and volume-rate. Time curves for K output likewise were similar with both stimuli, but correlation with acid output was high. Exogenous histamine is not essential to this K efflux, which may represent a basic process associated with glandular, neural, or muscular stimulation in general.
Electrical activity in mesenteric nerves after perfusion of gut lumen
Authors: Sharma K. N. , Nasset E. S.
Published: December 2017

Impulses from the peripheral cut end of mesenteric nerves to the intestinal loops of anesthetized cats were recorded oscilloscopically. Dogs with Thiry-Vella loops and with electrodes implanted in mesenteric nerves were used for chronic studies. The loops were perfused with different solutions at constant temperature and pressure. After glucose perfusion of the lumen the increase in frequency of firing was more marked in medium and larger fibers. After perfusion with single amino acids the increase was more conspicuous in smaller fibers. Amigen (amino acid mixture, dextrose, and salts) perfusion resulted in mixed patterns. No appreciable changes were observed with 0.9% NaCl, Tyrode's solution, and 0.025 n NaOH, but a slight increase was obtained with 0.025 n HCl. The possibility of some chemoreceptor mechanism in the small intestine is suggested. Its possible role in ingestion of food is discussed.
Active transport of iodide by choroid plexus of the rabbit in vitro
Authors: Welch Keasley
Published: December 2017

When incubated in vitro in a saline medium containing I131 as iodide, the chloride plexus accumulates this ion. The process by which iodide is transported resembles other extrathyroidal iodide concentrating mechanisms in that it is inhibited by a number of metabolic poisons and by perchlorate, thiocyanate, fluoroborate, fluorosulfonate, difluorophosphate, and nitrate. It depends for optimal function on the presence of oxygen, potassium, and calcium in the external medium, and is able to proceed at a reduced rate in the absence of glucose from the medium. Under optimal conditions approximately 5 x 10–11 moles 1–/mg dry weight/min are accumulated.
Coenzyme A and acetylation in various experimental obesities
Authors: Thompson Marilyn , Mayer Jean
Published: December 2017

Coenzyme A concentration and in vivo acetylation of sulfanilamide were determined in genetically obese-hyperglycemic mice, their lean littermates, littermates made obese by injection of gold thioglucose, yellow-obese mice, and Swiss mice. Metabolically obese mice show an increased total liver and kidney coenzyme A content. Rates of acetylation differ from one type to the other as does the effect of fasting on this parameter. These observations are discussed in the light of data on lipogenesis and cholesterogenesis previously obtained in these animals.
Nervous control of the cat nictitating membrane
Authors: Nystrom Richard A.
Published: December 2017

The nonstriated muscle fibers of the nictitating membrane respond to a single volley of nerve impulses with a slow twitch and three potentials: two independent waves followed by slow oscillations. On repetitive stimulation, the potentials overlap and sum algebraically. Pressure electrodes record only extracellular potentials. The first wave is elicited by nerve fibers which have a higher average threshold than the fibers which elicit the second wave. Eserine potentiates and hyoscine antagonizes the first wave. Dibenzyline, piperoxan, and reserpine antagonize the second wave. The nictitating membrane has functional adrenergic and cholinergic innervations; both cause retraction. Facilitation and summation can be either spatial, through the double innervation of each cell, or temporal, by diffusion of the transmitters from one cell to another. The cholinergic response is not maximal when the adrenergic response is maximal. The second wave is not potentiated by eserine at the same time as or before the potentiation of the first wave. Thus cholinergic innervation of adrenergic stores cannot explain the two electrical waves.
Effect of epinephrine on tubular reabsorption of glucose by dog kidney
Authors: Blake William D.
Published: December 2017

Standard renal clearance techniques have been used to estimate glomerular filtration rate (GFR) and tubular reabsorptive capacity for glucose (Tmg) in dogs when epinephrine was infused under a variety of conditions. In experiments conducted on dogs under conditions of hypoxia or during simultaneous determination of Tmpah with Na and K acetate infusion, epinephrine infusion had no consistent effect on either GFR or Tmg. However, in experiments on laparotomized dehydrated dogs, in experiments on animals receiving intravenous Metycaine, and in experiments uncomplicated by any of these additional procedures, epinephrine significantly increased Tmg (mean + 8.8%) without causing any significant change in GFR (mean + 1.5%). The data are interpreted as evidence for a metabolic action of epinephrine either directly or indirectly on the tubular transport system for glucose.
Effect of neuroactive drugs on production of fibrinolytic activity
Authors: Pohala Mary J. , Yen C. Y. , Singher Heron O.
Published: December 2017

Neuroactive drugs were investigated for their ability to produce a blood plasma fibrinolysin in experimental animals. Following intravenous injections of these drugs, blood samples were drawn and the plasma studied for fibrinolytic activity as indicated by the Astrup fibrin plate technique. Drugs inducing a small degree of fibrinolytic activity in dogs were acetylcholine hydrochloride, epinephrine hydrochloride, carbamylcholine chloride, physostigmine salicylate and prostigmine methylsulfate. The possible mechanism of drug-induced fibrinolysin as compared with the biological activation of profibrinolysin is interpreted on the basis of stimulation and release of catecholamines resulting from stimulation of sympathetic ganglia and the adrenal medulla.
Parathyroid action on calcium, phosphorus, magnesium, and citric acid in dairy cattle
Authors: Todd A. S. , Fosgate O. T. , Cragle R. G. , Kamal T. H.
Published: December 2017

Parathyroidectomized lactating Jersey cows were used to study the effects of parathyroid extract (PTE) on calcium, phosphorus, magnesium, and citric acid metabolism. Treatments consisted of 0, 2,200, and 4,400 U.S.P. units of PTE per 1,000 lb of body weight per day for three experimental periods. Calcium 45 and phosphorus 32 were administered orally 56 hr after initiation of PTE treatment. The plasma calcium, but not C45, showed an increase ( P < 0.01) with parathyroid hormone treatment. Calcium and Ca45 urinary excretion increased. In milk and plasma, high concentration of P32, but not of phosphorus, was associated with hormone administration. Total phosphorus and P32 in urine was increased with higher levels of PTE due to diuresis and greater concentration. Plasma levels of magnesium were not affected by PTE administration whereas an increase of magnesium concentration in milk occurred. A concomitant decrease was observed in the urinary excretion of magnesium. With increased PTE, citric acid levels of plasma and urine increased but remained constant in milk.
Mechanism by which potassium increases aldosterone secretion in the dog
Authors: Gann Donald S. , Cruz Juan F. , Casper Alfred G. T. , Bartter Frederic C.
Published: December 2017

Infusion of potassium-containing solutions into the carotid arteries of anesthetized dogs led to rates of adrenal secretion of aldosterone which were increased above control rates determined during infusion of dextrose and water. Infusion of potassium at the same rate into a brachial vein or femoral artery did not lead to increased rates of aldosterone secretion, despite similar rises in peripheral serum potassium concentration. The increase in rate of aldosterone secretion was not prevented by previous denervation of the carotid arteries. There was no correlation of increases in rates of aldosterone secretion with changes in rates of 17-hydroxycorticosteroid secretion. The results suggest that potassium may act at some intracranial site to stimulate increase in aldosterone secretion, probably through some mechanism other than ACTH release.
Acid secretion, potential difference, and resistance of elasmobranch stomach
Authors: Rehm Warren S.
Published: December 2017

The present report is concerned with in vitro studies on gastric mucosa of the skate, Raja eglentaria, the electric ray, Narcine braziliensis, and the shark, Negaprion brevirostris. Maximum secretory rates of from 0.65 to 2.7 µEq hr–1 cm–2 were found. An increase in the secretory rate from an initial low level was associated with an increase in potential difference (PD), a decrease in resistance, and an increase in the calculated short-circuit current. The average PD and resistance before the increase in the secretory rate was 2.2 mv (nutrient positive) and 268 ohms cm2. After the increase they were 6.4 mv and 199 ohms cm2. Thiocyanate (10–2 m) to nutrient resulted in a decrease of secretory rate to zero and an increase in PD and resistance. The results can be explained on the basis of the separate mechanisms theory of H+ and Cl– ion secretion on the assumption that the resistance in the Cl– ion limb of the circuit is considerably lower than that in the H+ ion limb of the circuit.
Luteinizing hormone release by cerebral cortex stimulation in rats
Authors: Taleisnik S. , Caligaris L. , Olmos J. De
Published: December 2017

Depletion of ovarian ascorbic acid from highly luteinized ovaries from rats was used as an index of endogenous liberation of luteinizing hormone (LH). When, in such rats, 2 µl of hypertonic saline was injected in the cerebral cortex, significant depletion of ovarian ascorbic acid took place compared with control animals. This stimulus was equally effective in different areas of the cortex that were explored. The mere implantation of the needle gave the same results. Procaine, added at 5% concentration to hypertonic saline, completely blocked cortical stimulation. The same effect was obtained by subcutaneous injection of estradiol benzoate (50 µg) or progesterone (1 mg). In animals with constant estrus, elicited by suprachiasmatic lesion, the response to cortical stimulation was blocked, but not completely. In these animals, however, an intense depletion of ovarian ascorbic acid was obtained by electrical stimulation of the hypothalamus. In animals with constant estrus, induced by injection of testosterone on the 2nd day after birth, the response was also affected. It is concluded that stimuli starting from the cerebral cortex can reach the hypothalamus and induce release of LH.
Atrial and ventricular force of contraction influenced by intracoronary injections
Authors: West James W.
Published: December 2017

A technique is presented for studying direct effects of drugs on atrial and ventricular contraction in the open-chest or closed-chest preparation. Selective coronary artery catheterization was combined with the Walton strain gauge for investigating local changes in atrial and ventricular contraction. This combined technique permitted observation of cardiac effects of a drug without the occurrence of generalized circulatory effects which frequently occur during intravenous administration. In addition, an increase or decrease in myocardial contraction could be confined strictly to the area supplied by the coronary artery injected. Generally, the strain gauge on the area of the heart within the distribution of the coronary vessel injected was the only one affected by the drug, whereas strain gauges on other parts of the heart outside the area supplied by the vessel were not affected. However, when a strain gauge was placed on the same or adjacent ventricle, but outside the area supplied by the vessel, directional changes occurred in this latter strain gauge which were opposite to those in the area injected.
Renal function in water snakes
Authors: LeBrie S. J. , Sutherland I. D. W.
Published: December 2017

Electrolyte and osmolar concentrations of ureteral urine were compared with serum in several species of water snakes. Hyperosmotic urine was never observed, even after 48 hr of water deprivation. This finding is consistent with the countercurrent theory which precludes urinary concentration when Henle's loops are absent, as in reptilian kidneys. The creatinine/inulin clearance ratio may exceed 2.0, suggesting tubular secretion of creatinine. Tubular secretion is further suggested by the fact that the clearance ratio approaches unity when plasma creatinine concentration is elevated. Variations in glomerular activity are reflected in urine flow in snakes as shown by a direct relationship between clearance of inulin (GFR) and urine flow In snakes solute excretion is dependent on an increase in functional tubular population, with a concomitant increase in filtered load and not a decrease in tubular solute reabsorption. Evidence for this concept is presented and indicates that, over a tenfold increase in GFR, snakes continue to excrete about the same per cent of their filtered load. Water reabsorption, on the other hand, appears to be similar in character to that seen in higher vertebrates. Proximally, it appears to be dependent on solute reabsorption ("obligatory"), whereas distally it is influenced by ADH ("facultative").
Relationship between acid-base balance and the central respiratory mechanisms
Authors: Katz R. L. , Ngai S. H. , Nahas G. G. , Wang S. C.
Published: December 2017

To study the effect of changes in acid-base balance on respiratory patterns, 2-amino-2-hydroxymethyl-1,3-propanediol (THAM, an organic buffer) and sodium bicarbonate (NaHCO3) were infused into midcollicular decerebrate, pontile, and medullary cats. NaHCO3 increased the arterial pH, HCO–3, and pCO2. THAM increased the arterial pH and HCO–3. The arterial pCO2 fell initially and then rose gradually with time. In the midcollicular decerebrate preparation with eupnea, NaHCO3 increased while THAM decreased the rate and amplitude of respiration. In the vagotomized pontile preparation with apneustic breathing, NaHCO3 accelerated and THAM decelerated the apneustic cycling; neither produced a significant change in amplitude. Larger doses of THAM abolished the apneustic cycling either by producing expiratory apnea or by prolonging the inspiratory phase. In the medullary preparation with periodic breathing, THAM decreased the rate with minimal changes in amplitude. The findings suggest that the respiratory effects of NaHCO3 and THAM were due to changes in intracellular pH and pCO2 and that all functional components of the respiratory center are influenced by changes in the acid-base status of the animals. Finally it is pointed out that elucidation of neural respiratory mechanisms requires definition of the acid-base state of the animal.
Cardiovascular function and norepinephrine-thermogenesis in cold-acclimatized rats
Authors: Evonuk Eugene , Hannon John P.
Published: December 2017

The cardiovascular and metabolic actions of norepinephrine (NE) and their inter-relationships were studied at normal room temperature in anesthetized, warm-acclimatized (W-A) (26 ± 1 C) and cold-acclimatized (C-A) (3 ± 1 C) rats. The cardiac output, heart rate, stroke volume, arterial pressure, right atrial pressure, and systemic resistance were measured prior to NE infusion; during NE infusion (2 µg/min) at the 25, 50, 75, and 100% levels of increased metabolism; and after infusion of NE had ceased. Norepinephrine caused a greater increase in the cardiac output, heart rate, stroke volume, and right atrial pressure in the C-A animals than it did in W-A animals. During the early metabolic response to NE (i.e., up to 25% increase in O2 consumption) there was a marked increase in the arterial pressure of both W-A and C-A rats, with the latter showing the greater maximum response. Beyond the 25% level of increased metabolism the arterial pressure and concomitantly the systemic resistance of the C-A animals declined sharply to the preinfusion levels where they remained throughout the course of infusion. In contrast to this, the arterial pressure and systemic resistance of the W-A animals remained high. It was concluded that norepinephrine-calorigenesis in the C-A rat is supported by a greater capacity to increase the cardiac output and an ability to preferentially reduce the systemic resistance to actively metabolizing areas (i.e., the viscera).
Patterns of conduction in smooth muscle
Authors: Nagai T. , Prosser C. L.
Published: December 2017

In sheets of circular intestinal muscle, electrical waves conduct in all directions, much faster and with less decrement in the long than in the transverse axis of the fibers. Need for interfiber summation is shown by failure to initiate conducted spikes with stimulating electrodes less than 100 µ diameter. Conduction is in bands with occasional entry from one band into another. Minimal latency occurs in a 1–2-mm band in line with stimulating electrodes. Diagonal conduction was not observed, but double spikes represent direct conduction followed by re-entry into a band from a parallel conducting path. Records with double microelectrodes, 1–700 µ apart, showed no measurable latency difference when both were in the same fiber but normal velocity at separations greater than 50 µ.
Neurogenic control of skeletal muscle vascular resistance in hemorrhagic shock
Authors: Rothe Carl F. , Schwendenmann Fred C. , Selkurt Ewald E.
Published: December 2017

The neural control of the resistance vessels of a gracilis muscle, isolated except for its nerve, was monitored during the various phases of hemorrhagic shock in dogs. The circulation to the muscle was maintained at a constant pressure of 160 mm Hg with a pump, using blood from a donor dog to eliminate any blood-borne factors elaborated by the shock dog. The degree of neural vasoconstriction was evaluated by periodically blocking the nerve with cold and measuring the subsequent changes in blood flow. Vasoconstriction followed hemorrhage. In many of the experiments there was evidence of loss of neural control of vascular resistance after prolonged hypotension following hemorrhage or terminally following the progressive decline in blood pressure after transfusion. This reduction of neurogenic vasoconstriction may contribute to cardiovascular collapse during hypotension. Following transfusion, however, vasoconstriction greater than control was generally seen, suggesting a functioning homeostatic mechanism acting to maintain the declining arterial blood pressure. Thus, irreversibility following transfusion is not the result of a loss of neurogenic control of the vascular resistance of skeletal muscle under the conditions used.
Influence of osmolarity of perfusate on contractility of mammalian myocardium
Authors: Koch-Weser Jan
Published: December 2017

The effect of changes in the osmolarity of the perfusing fluid on strength and time course of myocardial contraction was studied in cat papillary muscles and atrial strips. Osmolar concentration was varied by adding up to 750 mm sucrose or mannitol to a slightly hypoosmolar solution, leaving molar concentrations of the original solutes unchanged. Optimum osmolarity for tension development by papillary muscles was close to that of serum (330 mosmol/ liter), but for atrial muscles was 150 mosmol/liter higher. Osmolarity changes apparently influence contractility by altering the intracellular water concentration. Increases of osmolarity up to the optimum augment tension development by increasing the degree of activation of the contractile elements. This may be due to increased concentration of calcium in a superficial area of the fiber. Increases of osmolar concentration above the optimum lower developed tension, probably by reducing the intrinsic speed of the muscle. Tension development in response to external stimuli is abolished by raising osmolarity to three times that of serum (1 osmol/liter). Spontaneous contractions cease in solutions of twice normal osmolar concentration.
Effects of certain inhibitors on renal excretion of salt and water
Authors: Strickler James C. , Kessler Richard H.
Published: December 2017

The direct proportionality between renal oxygen consumption and sodium reabsorption suggests a linkage between cation transport and the electron transport system (ETS). We have studied the effects of in vitro inhibitors of the ETS on sodium reabsorption in the dog kidney. Compounds known to block O2 consumption or reduce tissue levels of adenosine triphosphate (ATP) were infused in millimolar quantities into a renal artery of anesthetized dogs. We observed a unilateral diuresis following the administration of cyanide, antimycin-A and iodoacetamide; no diuresis was observed following administration of 2,4-dinitrophenol, azide, and phlorizin. These latter agents block the synthesis or facilitate the degradation of ATP. Negative results were also observed with phthiocol (a naphthoquinone), malonate, and Amytal, inhibitors of specific substrates of ETS. We interpret our results as follows. Inhibition of sodium reabsorption by cyanide and antimycin-A supports the hypothesis that renal cation transport is dependent in part upon oxidative metabolism. The failure of phlorizin and 2,4-dinitrophenol to affect sodium reabsorption suggests that cation transport may be independent of ATP synthesis or concentration in renal tissues.
Polarographic studies of energy metabolism in rat liver homogenates
Authors: Ziegler F. D. , Strickland E. H. , Anthony Adam
Published: December 2017

Oxidative phosphorylation and respiratory regulation were studied in rat liver homogenates by use of the oxygen electrode. Addition of 250 µm ADP to rat liver homogenates containing succinate, α-ketoglutarate, ß-hydroxybutyrate, or glutamate stimulated respiration 300–600%. Respiration declined sharply after the added ADP was phosphorylated. ATP, especially in the presence of MgCl2, also stimulated homogenate respiration, though much less effectively than ADP at equivalent concentrations below 1 mm. Amytal or malonate, in concentrations sufficient to depress substrate-ADP respiration, had no effect on substrate-ATP respiration. ADP:O ratios were measured and corrected for ATPase activity. Values obtained were 2.0, 4.1, and 3.0 for succinate, α-ketoglutarate, and ß-hydroxybutyrate, respectively.
Pressor activity of renal venous effluent of normal and hypertensive rats
Authors: Sokabe Hirofumi , Grollman Arthur
Published: December 2017

The pressor response induced by the renal venous effluent of a kidney grafted to a bilaterally nephrectomized rat has been shown to be a consequence of the unavoidable manipulation involved in the procedure rather than a consequence of the resting rate of secretion of renin as claimed by previous investigators. The procedure failed to demonstrate the presence of a pressor agent in the renal venous effluent of either the normotensive or hypertensive rat.
Effects of endotoxin on renal function and hemodynamics
Authors: Gillenwater Jay Y. , Dooley Elmo S. , Frohlich Edward D.
Published: December 2017

The injection of lethal doses of Salmonella typhosa endotoxin in the dog produced an initial (18 sec) transient vasoconstriction followed by a secondary intense vasoconstriction within 5–10 min. Renal arterial pressure remained elevated for 30 min. Since local infusion of phentolamine blocked the secondary renal vasoconstriction it is suggested that the persistent vasoconstriction was due to catecholamine release during the systemic hypotension. After endotoxin injection there was a marked decrease in all renal functions. The hemodynamic effect was eliminated in one kidney by infusing phentolamine locally and holding renal blood flow constant in one group of animals thus enabling comparison of this kidney with the contralateral undisturbed kidney. In the kidney in which vascular effects were eliminated there was no alteration in renal functions after systemic or local endotoxin injection. These data, therefore, show that the principal effect of endotoxin on the kidney is hemodynamic and not nephrotoxic.
Respiratory functions of blood of the yak, llama, camel, Dybowski deer, and African elephant
Authors: Bartels Heinz , Hilpert Peter , Barbey Klaus , Betke Klaus , Riegel Klaus , Lang Ernst Michael , Metcalfe James
Published: December 2017

Blood samples from a yak, llama, camel, deer, and African elephant were analyzed for oxygen capacity, "standard bicarbonate" content, oxygen dissociation curve, and the magnitude of the Bohr and Haldane effects. These parameters of the respiratory function of the blood have been related to the morphology of the red cells, to the weights of the animals, and to the most important electrolytes in the erythrocytes and in the plasma. The high affinity for oxygen described previously for llama blood is shared by its relative, the camel. Both these animals have a high concentration of hemoglobin within their erythrocytes. Blood from the African elephant showed the greatest affinity for oxygen among the subjects studied.
Gastric response to topical histamine; subcutaneous dose-response relation
Authors: Hollander Franklin , Schapira Adolfo
Published: December 2017

Canine Heidenhain and Pavlov pouches were filled with histamine solutions (2–10–7 mg base/ml) for 30 min. Following drainage, secretion was collected continuously in 15-min samples. Volumes were generally too low for systematic acidity titrations; pHs yielded scant evidence of a response. In another series of experiments, topical application and subcutaneous injection were used conjointly, following a control run with subcutaneous injection alone (i.e., by the tandem experiment procedure). These responses were more definitive but complex; i.e., the subcutaneous response tended to be augmented at lower concentrations, and partially or completely inhibited at higher ones. These results are analogous to a variety of phenomena reported by others, including the dose-response relation for subcutaneous histamine alone, the comparative responses to histamine injected by two different routes, the responses to topical application of cholinergic agents, alcohol, acetoacetamide, etc. This complex response to topical histamine is interpreted in terms of the Arndt-Schulz Law.
Effects of carbohydrates on secretion of insulin from isolated rat pancreas
Authors: Grodsky Gerold M. , Batts Adrienne A. , Bennett Leslie L. , Vcella Carl , McWilliams Nancy B. , Smith Desmond F.
Published: December 2017

The effect of carbohydrates on the secretion of immunochemically measurable insulin was studied in an isolated perfused pancreatic preparation from the rat. Degradation of circulating insulin (as measured by chromatographic examination of added insulin-I131) was less than 15% during the 4-hr experimental period. Without the addition of glucose, or at glucose concentrations of less than 50 mg/100 ml, insulin secretion was not detectable. At glucose concentrations of 50–150 mg/100 ml, insulin secretion occurred immediately and persisted throughout the experimental period. Insulin secretion was further increased by increasing glucose concentration to 150–500 mg/100 ml. The incidence of islet cell degranulation increased with increasing insulin secretion, suggesting that glucose stimulated secretion of stored insulin faster than synthesis of insulin de novo. Galactose, xylose, l-arabinose, pyruvate, and 2-deoxyglucose in concentrations of 600 mg/100 ml did not stimulate insulin secretion. Mannose stimulated the pancreas equally as well as glucose. Fructose was also active, but was less effective than glucose. Neither 2-deoxyglucose nor galactose blocked the insulin secretion by glucose. The data suggest that secretion of insulin is stimulated by a metabolite or a product resulting from the metabolism of glucose which can also be supplied by other metabolizable sugars.
Nature of electrolyte exchange in isolated uterine smooth muscle
Authors: Kao C. Y. , Siegman M. J.
Published: December 2017

Data are presented to show the marked changes in contents of water, sodium, potassium, and chloride in isolated rabbit myometrial strips when these preparations are incubated in Krebs-bicarbonate solution. The changes are interpreted to be composed of an initial passive redistribution and a later active transport phase. In support of this interpretation are: 1) in the passive redistribution phase, the intracellular ionic concentrations approached those in the medium, and 2) at 0 C, only passive redistribution was present, while at 25 and 37 C, restoration towards the normal ionic distribution, i.e., active transport, also occurred. Movement of water is largely isotonic and movement of chloride appears to be largely passive. Much potassium is actively accumulated in excess of the amount required by Donnan distribution. In contrast to the estrogen-dominated myometrium, the progesterone-dominated myometrium showed a lesser extent of passive redistribution and an earlier appearance of active transport phenomena. In both types of myometrium the net amounts of sodium extruded and potassium reaccumulated are balanced, as are the rates of the reciprocal net movements.
Development of tissue hypoxia during progressive hyperthermia in dogs
Authors: Frankel H. M. , Ellis J. P. , Cain S. M.
Published: December 2017

Heart rate, mean arterial pressure, respiratory rate, minute volume, arterial blood, Po2, Pco2, pH, hemoglobin saturation, lactic acid, and pyruvic acid were determined on anesthetized dogs during progressive hyperthermia. Heart rate increased as rectal temperature ( Tr) increased. Mean arterial pressure began to decline at Tr between 41 and 42 C. Respiratory rate and minute volume reached maximum values at temperatures around 42 C. Arterial Po2 and hemoglobin saturation did not decrease until rectal temperature exceeded 42 C. Pco2 decreased and pH increased from control values as minute volume increased. Arterial excess lactate showed the most marked rise at Trs between 41 and 42 C. Failure of external respiration is not the primary physiological failure during progressive hypothermia but the development of tissue hypoxia may be.
Food and water intake following lesions or electrical stimulation of the amygdala
Authors: Grossman Sebastian P. , Grossman Lore
Published: December 2017

In the first experiment, very small bilateral lesions were placed into the posteroventral amygdala of 12 rats. Food and water intake was recorded for 6 weeks prior to the operation and for 12 weeks following it. Water consumption rose sharply immediately after the operation and remained near the maximal level for 12–16 days. Food intake increased gradually, reaching a maximum after 3–4 weeks. Feeding and drinking returned to near-normal within the 12-week observation period. In the second experiment, electrodes were implanted into anterior, medial, and posterior portions of the ventral amygdala. Electrical stimulation of anterior points inhibited food intake but increased water consumption. Stimulation of the medial placements produced no consistent effect. Both feeding and drinking behavior were inhibited during and immediately following the stimulation of posterior points. Lesions in the anterior area increased food intake but reduced water consumption. Medial lesions reduced water intake but had no reliable effect on feeding behavior. Posterior lesions produced hyperphagia and hyperdipsia. The lesion effects appeared to be permanent.