bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Cooling on Neuromuscular Transmission in the Rat
Authors: Li Choh-Luh
Published: December 2017

When the rat was being cooled from normal body temperature to 10°C, the resting membrane potentials recorded from the endplate region of the gracilis anticus muscle of the rat showed no significant change, with a mean value of –79.5 ± 4.6 mv (S.D.). The resting membrane potentials at body temperatures below 10°C were lower; the mean value at 10°–4°C was –71 ± 8.5 mv, and at 4°–0°C, –32 ± 10.2 mv. Below 0°C resting membrane potential was not recorded. The responses to nerve stimulation did not change at body temperatures between 36° and 15°C. Below 15°C the duration of the spike responses became longer and at times the responses showed no spike potentials; at 5°–4°C no spikes but endplate potentials were recorded. The miniature endplate potentials could be recorded at body temperature as low as 4°C but not below. The performance of neuromuscular transmission was most efficient at body temperature above 15°C, and was impeded at 15°C and blocked at 5°C. At 4°C the nerve ceased to conduct although contraction of the muscle could be produced by direct stimulation at body temperatures as low as 1°C. During the process of cooling some of the muscle fibers would fibrillate. In frost bite lesions, produced by cooling the extremity to –2°C for 2 hours, muscle resting potentials and miniature endplate potentials were absent and there was no response to direct or indirect stimulation of the muscle.
Intra-Axonal Injection of Biologically Active Materials
Authors: Brady Roscoe O. , Spyropoulos Constantine S. , Tasaki Ichiji
Published: December 2017

An improved method for injection of chemicals into the squid giant axon is described. A large number of metabolically active materials were found to be without any effect upon the action potential. Tetraethylammonium chloride produced a striking prolongation of the action potential. Cocaine and ethanol caused a transient reduction in the amplitude of the action potential. A filter paper eluate was found to contain materials which caused repetitive firing followed by a reduction in amplitude of the action potential and finally inexcitability.
Metabolism of Sulfobromophthalein Sodium (BSP) in the Rat
Authors: Krebs John S. , Brauer Ralph W.
Published: December 2017

Chromatographic analysis of crystalline BSP used for clinical test of liver function showed the BSP to be chromatographically homogeneous. Chromatographic analysis of BSP excreted into bile of the rat showed the excreted BSP to be composed of three similarly colored, but distinct compounds. The compound which had the same chromatographic mobility as the BSP injected amounted to only 9.6% of the BSP injected. The distribution of the compounds derived from BSP showed a continuous change during the course of excretion, but the average distribution for a 40-minute collection period after injection of the BSP was the same for several rats. Metabolic changes of BSP were found among several animal species, and the chromatographic mobilities and distribution of the compounds showed species differences. Spectrophotometric absorption curves of BSP and compounds derived from BSP in the rat were found to overlie exactly, but the derived compounds showed changes in molecular extinction coefficients. One of the derived compounds had the same bromine content as BSP. Incubation of the derived compounds with ß-glucuronidase did not regenerate BSP.
Impairment of the Enzymatic Inactivation of Adrenal Cortical Hormones Following Passive Venous Congestion of the Liver
Authors: Yates F. Eugene , Urquhart John , Herbst Arthur L.
Published: December 2017

Acute hepatic venous congestion severely impairs the enzymatic reduction of ring A of desoxycorticosterone, cortisone and hydrocortisone in male and female rats. Preliminary experiments with aldosterone indicate a similar impairment in metabolism. Sham operations do not have this effect. The defect in the inactivation of these hormones persists for as long as 9 months after the onset of hepatic venous congestion, although some recovery is evident. It is suggested that the secondary aldosteronism of congestive heart failure may be accounted for in part by this enzymatic lesion.
Respiration in the Hibernation of the 13-Lined Ground Squirrel
Authors: Landau Barbara R. , Dawe Albert R.
Published: December 2017

Respiratory rate, heart rate and body temperatures were recorded simultaneously in the 13-lined ground squirrel ( Citellus tridecemlineatus) throughout the hibernating cycle. An induction trend may appear at any time during the latter part of arousal. It may lead to the hibernating state, or it may give way to the continuation of arousal, hence neither induction nor arousal appears to be an ‘all-or-none’ phenomenon. In hibernation, respiration consists of one to two deep sighs followed by apnea of variable duration, averaging 1–3 breaths/min. The heart rate is often arrhythmic, but averages 7–8 beats/min. As the frequency of the sighs change, other shallow rhythmic breaths appear very early in arousal, and increase in rate and amplitude to marked hyperventilation. Heart rate also increases rapidly and without arrhythmia, but in late arousal various stimuli will elicit momentary respiratory and cardiac arrest. In transition stages, respiratory lead heart rate changes, except during early arousal and late induction when respiratory and heart rates are linearly related. The apparent initiatory action of respiration further implicates the respiratory muscles in the heat production of arousal.
Phrenic Cross Innervation of the Hemidiaphragm in the Dog
Authors: Ogawa T. , Jefferson N. C. , Necheles H.
Published: December 2017

In acute experiments on mongrel dogs, the innervation of each hemidiaphragm was investigated. In approximately 30% of the animals a division of the posterior branch of the left phrenic nerve was found to cross to the right side, innervating part of the right crus of the diaphragm immediately to the right of the esophageal hiatus. A similar cross innervation from right to left was not found; neither was a cross innervation from an anterior branch of the phrenic nerve found. The physiologic significance of cross innervation in relation to trophic maintenance of the muscle of the diaphragm by sympathetic innervation is discussed.
Mechanism of the Wenckebach-Luciani Cycles
Authors: Rosenblueth A.
Published: December 2017

The development of Wenckebach-Luciani cycles was studied in dogs anesthetized with pentobarbital, with the heart denervated, the S.A. node crushed, and the adrenals ligated. When the auricle is stimulated with increasing frequency there is at first a 1:1 correspondence between the A and the V impulses. At a critical frequency the correspondence becomes nA:( n – 1)V, where n > 2. At higher frequencies, n = 2, i.e., the ventricle alternates. The hypothesis that the cycles ( n > 2) are due to cumulative impairment of the propagating system is deficient. The cycles are due to the modulation of two frequencies, that of the stimuli and that determined by the longest functional refractory period of the conducting elements. The laws of the cycles are formulated mathematically. V-A cycles also develop when the ventricle is stimulated. They are often obscured by the appearance of impulses that return from the auricle to the ventricle. The mechanism of these cycles is similar to that of the A-V cycles.
Inhibition of Vagally Stimulated Gastric Acid by the Pyloric Antrum
Authors: Shimizu H. J. , Morrison R. T. , Harrison R. C.
Published: December 2017

It has been previously demonstrated that gastric acid production of antral and intestinal origin is inhibited by acidification of the antrum. In this experiment a vagally innervated gastric pouch (Hollander) and an excluded antral pouch were constructed in four animals, two of the antral pouches being vagally innervated and two denervated. The gastric pouches were stimulated to secrete in response to insulin hypoglycemia and the effect of acidification of the antrum tested. It was found that gastric secretion was reduced by acidification whether the antrum was denervated or not, the difference between the two being insignificant. It was concluded that the gastric acid produced in response to vagal stimulation is reduced by acidification of the antrum and that denervation of the antrum did not influence this result.
Creatine and Creatinine in Tissues and Urine of Mice With Hereditary Muscular Dystrophy
Authors: Kandutsch A. A. , Russell Alice E.
Published: December 2017

Muscle creatine in mice with hereditary muscular dystrophy averaged 20% lower than normal when values were based on wet weight of muscle. Part of the apparent decrease may be the result of an approximately twofold increase in total lipid. The concentration of creatine in liver and kidney was similar in dystrophic and normal mice. The ratio of urinary creatine to creatinine was similar in both groups when the diet was laboratory chow. It was increased in dystrophic but not in normal mice when they were fed oatmeal or a synthetic diet. The injection of creatine resulted in an increase in urinary creatine that was similar in both groups while supplementing the diet with vitamin E did not reduce the creatinuria of dystrophic mice to normal levels. Dystrophic mice appeared to be able to remove injected creatine from the blood stream somewhat more rapidly than did normal mice.
Interaction of Actomyosin and Adenosinetriphosphate as Studied With Glycerol-Extracted Cardiac Muscle Bundles
Authors: Benson Ellis S. , Hallaway Ben E.
Published: December 2017

Glycerol-extracted muscle bundles were obtained from the right and left ventricles of dogs. Isometric tension developed on addition of adenosinetriphosphate (ATP) and resistance to stretch of the extracted bundles and the rate of ATP hydrolysis of the myofibrillar components of the bundle were studied. Effects of temperature, ionic strength, pH and concentrations of ATP, sodium, magnesium and calcium were evaluated. The results indicated that the contractile phenomenon producing tension is a complex of at least two underlying reactions one of which promotes contraction ( R1) and the other ( R2) relaxation. Which of these reactions limits tension development is determined by the concentration of ATP. The concentration at which the transition takes place between R1 as the limiting reaction to R2 is a function of temperature, ionic strength, pH and the concentration of calcium ions. R1 appears to be associated with the hydrolysis of ATP and this may be the energy-supplying reaction. Certain findings in regard to the effect of concentration of divalent cations on the contractile response and the rate of hydrolysis are difficult to reconcile, however, with the contention that R1 is a reaction in which ATP is hydrolyzed. At very low concentration of Mg and Ca, hydrolysis is strikingly inhibited though contraction takes place. Furthermore, concentrations of Mg of the order of 2 x 10–2 m inhibit enzymatic hydrolysis and promote contraction. Concentrations of Ca of 10–2 m inhibit contraction but accelerate ATP hydrolysis.
Factors Influencing Serum Copper and Ceruloplasmin Oxidative Activity in the Rat
Authors: Meyer B. J. , Meyer A. C. , Horwitt M. K.
Published: December 2017

The effect of turpentine, estradiol benzoate and epinephrine hydrochloride on the copper concentration and paraphenylenediamine oxidase activity of serum were studied in the male albino rat. All three of these substances raised the serum copper level and paraphenylenediamine oxidase activity in both ‘control’ and ‘adrenalectomized’ animals, turpentine being the most active. The average serum copper level is approximately the same for normal humans and rats, while the phenylenediamine oxidase activity of normal human serum is about 2–3 times as high as that of rat serum. The data are discussed with relation to the known facts about serum copper in normal subjects and mental patients.
Renal Excretion of Radioiodide in Rats
Authors: Halmi N. S. , King L. T. , Widner R. R. , Hass A. C. , Stuelke R. G.
Published: December 2017

Page 383: N. S. Halmi, L. T. King, R. R. Widner, A. C. Hass and R. G. Stuelke, "Renal Excretion of Radioiodide in Rats." Column 1, line 9 should read: U/P1131 was again a valid measure of U/P1127.
Gastric Secretion and Free Histamine in Urine
Authors: Irvine William T. , Code Charles F.
Published: December 2017

Simultaneous determinations of the hourly outputs of free histamine in the urine and free acid in the juice from Heidenhain gastric pouches were made in dogs after the ingestion of meat. The gastric secretory response to the meal was separated into intestinal and gastric components. The rough parallelism, noted by others, between the outputs of acid in the gastric juice and free histamine in the urine after the meal was verified. When the meat was placed in the jejunum the output of histamine in the urine promptly increased while the output of acid was minimal or absent. Later, the output of acid increased while the output of histamine declined. Meat placed in the isolated stomach produced active secretion of acid but no increase in urinary histamine. No increase of urinary histamine followed a meal of bread and milk. During nervous secretion induced by insulin hypoglycemia, the output of free histamine in the urine did not change.
Distribution of Glutamine Metabolizing Enzymes and Production of Urinary Ammonia in the Mammalian Kidney
Authors: Richterich Roland W. , Goldstein Leon
Published: December 2017

The distribution of the glutamine metabolizing enzymes was studied in the kidney of four mammalian species (dog, rat, rabbit and guinea pig). Glutaminase I activity of whole kidney was highest in the dog (19.1 µm NH3/gm/min.), intermediate in the rat (8.1 µm NH3/gm/min.), and low in the guinea pig (1.1 µm NH3/ gm/min.) and rabbit (0.6 µm NH3/gm/min.). In all four species, enzyme activity was highest in the cortex and inner medulla. Glutaminase II and glutamine synthetase activity were lower than glutaminase I activity in all four species. Both glutaminase II and glutamine synthetase activity were found only in the cortex and outer medulla. The relationship of the glutamine metabolizing enzymes to the production of urinary ammonia is discussed.
Some Quantitative Studies on Phlorizin Inhibition of Glucose Transport in the Kidney
Authors: Lotspeich William D. , Woronkow Seraphim
Published: December 2017

The constant infusion of phlorizin in small amounts (0.6–100 µg/kg/min.) reduces maximal glucose transport rate (Tmg) by 20–70% in dogs. Thus phlorizin is a much more powerful inhibitor of glucose transport than hitherto supposed. From these experiments it is reasonable to conclude that effective phlorizin concentrations in the intact animal are in the same range as those shown to produce effects on sugar transport and oxidative metabolism in vitro. Complete inhibition of glucose transport during constant infusion of phlorizin was never produced even at rates of 100 µg/kg/min. Experiments on citrate metabolism in vitro and Tmg in vivo show that phlorizin does not act at a site sensitive to 2,4-dinitrophenol. The findings presented are discussed in the light of a cell membrane theory of phlorizin action.
Response to Rapid Water, Sodium and Dextran Loads of Intact Ringer's-Infused Unanesthetized Dogs
Authors: Stamler J. , Dreifus L. , Katz L. N. , Lichton I. J.
Published: December 2017

In Ringer's-infused unanesthetized intact dogs, rapid intravascular injections (200 cc) caused an enhanced diuresis, regardless of injection site. Injection of Ringer's solution induced an immediate and sustained increment of H2O, Na and total solute diuresis. These changes were correlated with increases in venous pressure, reductions in hematocrit and in plasma oncotic pressure (except in the dextran experiments). They were not correlated with patterns of GFR, RPF, plasma Na and total solute, filtered electrolyte load, blood pressure of heart rate. Injection of 3.75% glucose-in-water induced a sustained increment of H2O diuresis, with only a transient or no increase in Na and total solute diuresis. Injection of 6% dextran-in-water induced a complex, variable response, with sustained enhanced diuresis of H2O, Na and total solutes in some experiments. It is suggested that two adjustments, volume and composition homeostatic correction, are operative, the former immediate, the latter delayed (possibly hormonal). It is further suggested that the former is a response to circulating intravascular volume expansion, possibly ‘sensed’ by stretch and/or pressoreceptors.
Effects of Thyroid Hormones on Ring A Reduction of Cortisone by Liver
Authors: Yates F. Eugene , Urquhart John , Herbst Arthur L.
Published: December 2017

Triiodothyronine increases total hepatic capacity for in vitro reduction of ring A of cortisone by 38% in both male and female rats. Thyro-parathyroidectomy decreases it 56% in males and 48% in females. These alterations in thyroid state influence hepatic reduction of corticosteroids in several ways: a) the total amount of Δ4-steroid hydrogenases in the liver may be altered, both by changes in liver size and by changes in amount of enzyme per gram of liver; and, b) the activity per gram of liver can also be altered through variations in coenzyme (TPNH) availability. These effects of thyroid hormones provide an enzymatic basis for the alterations in biological half-life of adrenal steroids observed in hyper- and hypothyroidism. A very close correlation ( r = 0.97) between total hepatic capacity to inactivate cortisone and the size of the adrenal glands was found. It is suggested that the rate of ring A reduction of corticosteroids by liver determines the rate of ACTH secretion in unstressed animals.
Mechanism of Arterial Pressure Response to Histamine-Liberators
Authors: Masson G. M. C. , Corcoran A. C. , Franco-Browder S.
Published: December 2017

Experiments with pharmacologic blocking agents indicate that, in the barbiturate anesthetized rat, the depressor response to injected histamine-liberators is attributable to the release into the circulation of a mixture of serotonin and histamine. The data do not suggest participation of any other depressor agent. The effect of such release on blood pressure can be simulated by infusion of a mixture of serotonin and histamine, indicating that the depressor response to endogenous release or exogenous administration is undistinguishable, although tissue responses are very different. The depressor responses to histamine liberators or to infusions of histamine-serotonin mixtures can be suppressed by pretreatment with an antihistamine such as promethazine and an antiserotonin agent such as BOL. Inhibition is also obtained with drugs possessing both properties such as phenoxybenzamine.
Aorta Electrolytes of Hypotensive Potassium-Deficient Rats
Authors: Freed S. Charles , St. George Shirley , Rosenman Ray H.
Published: December 2017

The hypotension of potassium-deficiency is associated with a decrease in aorta potassium concentration, the sodium content remaining unchanged, resulting in a high sodium/potassium ratio. Loss of arterial tone may result and thus contribute to the lowering of blood pressure. Cortisone administration to such rats does not alter the low aorta potassium content but appreciably reduces the sodium concentration. The return to a more normal sodium/potassium ratio in the aorta following cortisone may restore the arterial tone and thus explain the blood pressure rise to normal levels.
Effect of Anesthesia and Hepatic Sampling Site Upon Hepatic Blood Flow
Authors: Gilmore J. P.
Published: December 2017

Pentobarbital sodium (30 mg/kg) did not significantly alter the estimated hepatic blood flow of the dog, but did initially decrease the arterial-hepatic venous oxygen difference. Hepatic venous samples obtained simultaneously from the right and left side of the liver did not on the average show significant differences in bromsulphalein concentration, oxygen content or hematocrit.
Acid Secretory Responses to Histamine and the Parietal Cell Mass in the Dog
Authors: Marks I. N. , Komarov S. A. , Shay Harry
Published: December 2017

Gastric secretion in response to graded doses of histamine, given subcutaneously at 10-minute intervals, was obtained from whole stomachs in acute experiments on six anesthetized dogs. Extragastric contamination was excluded. Each dose was maintained until a steady rate of secretion was reached, after which the dose was increased. The experiment was continued until a maximal secretory response was attained. The log dose/response curves for rates of secretion attained with different doses, corresponding acid outputs and, in some experiments, acid concentration, were normal-sigmoid in character. The maximal secretory responses were greater than those previously observed in the intact and the vagally denervated total pouch dog, although the histamine dosages found necessary to effect these responses were within the previously reported range. The total number of parietal cells in the stomach, estimated by a technique previously employed in guinea pigs and man, ranged from 1.2 to 1.6 billion. The magnitudes of both the maximal secretory response and the parietal cell mass in the dog were similar to the respective values reported in human beings free of gastroduodenal ulceration.
Measurement of Uterine Blood Flow and Uterine Metabolism
Authors: Assali N. S. , Dasgupta K. , Kolin A. , Holms L.
Published: December 2017

Uterine blood flow has been measured with a chronically implanted miniature electromegnetic flow meter in unanesthetized pregnant sheep and dogs during spontaneous and oxytocin induced labor and followed in the same animal for several postpartum days. In either spontaneous or oxytocin induced labor, uterine contractions are accompanied by a significant decrease in uterine blood flow and relaxations by the return of the flow to or higher than control values. The decrease is roughly proportional to the intensity of uterine contraction. When the contraction is of a tetanic nature and not followed by relaxation, uterine ischemia is so severe that the fetus might succumb. After the delivery of the fetus and before the expulsion of the placenta, uterine blood flow falls slightly. However, after separation and expulsion of the placenta, uterine blood flow falls precipitously. Thereafter, a very slight and progressive decrease continues for several days paralleling uterine involution.
Effects of Aldosterone on Blood Pressure and Electrolyte Distribution in the Rat
Authors: Friedman Sydney M. , Friedman Constance L. , Nakashima Miyoshi
Published: December 2017

Aldosterone racemate, 20–40 µg, induced a small rise in blood pressure in the intact or nephrectomized rat following subcutaneous or intravenous but not intraperitoneal injection. It was effective in restoring the depressed pressure of the adrenalectomized animal towards normal within 60 minutes of intravenous administration. Extracellular fluid volume (inulin space) and extracellular Na were increased in the nephrectomized rat, but not in the nephrectomized-adrenalectomized animal during the restoration of blood pressure. Aldosterone racemate, 20 µg, also caused a characteristic increase in pressor sensitivity to Pitressin within 30 minutes of subcutaneous administration. Based on these findings and our previous studies, argument is presented to link the neurohypophysis and mineralocortex, both acting by different means in the same direction, with the control of sodium distribution between cells and environment. Vascular smooth muscle tonus is considered to be a function of the continuously regulated sodium gradient and thus of the sodium transfer systems. Plasma sodium changes in diverse states with altered blood pressure are considered to be evidence of attempts at compensation for an altered sodium gradient rather than as causal in themselves.
Transfer of donor immunological reactivity to x-irradiated F1 hybrid mice by injected parental bone marrow
Authors: Cole L. J. , Garver R. M. , Ellis M. E.
Published: December 2017

Mice of the (LxA)F1 strain were exposed to an ld100 dose of x-rays (870 r), and injected with bone marrow cell suspensions from A-strain mice. Excellent protection against death was observed during the first 3 weeks, followed by secondary ‘homologous’ deaths during the ensuing weeks. When A-strain (parental strain) spleen cells were injected, together with A-strain bone marrow, the protective effect was annulled. When A-spleen cells were injected together with LAF1 bone marrow cells into irradiated LAF1 mice, again no protection was observed. However, injected LAF1 spleen cells did not influence adversely the course of protection of x-irradiated A-strain mice by injected A-bone marrow. The findings formed the basis for an experimental test system for detecting the presence of A-lymphoid cells in the tissues of irradiated LAF1 mice which had been injected with A-bone marrow. The data indicate that the spleen and thymus of LAF1 mice 21 days after irradiation and injection of A-marrow contain A-lymphoid cells which when injected, in turn, into irradiated LAF1 mice treated with LAF1 marrow, annuls the protective effect of the injected marrow. It is concluded that a reaction (of an immunological nature) of the injected bone marrow cells, or their progeny, against the host tissues, contributes to the phenomenon of the late deaths. The significance of these results with respect to the problem of ‘homologous disease’ in lethally x-irradiated mice treated with homologous bone marrow, has been discussed.
Red blood cell volume and distribution after bleed-out in the rat as determined by Cr51-labeled red blood cells
Authors: Muelheims Gerhard , Dellenback Robert , Rawson Ruth
Published: December 2017

The distribution of red blood cells after bleed-out was determined in 20 Nembutalized rats (307.1–484.4 gm body weight), using Cr51-labeled red blood cells. The normal red blood cell volume was 2.20 ± 0.25 ml/100 gm body weight. On the average 68.5% of the red blood cells were removed by the bleed-out. Per total tissue the muscle contained most of the red blood cell volume remaining after bleed-out and together with the liver and bone about 65%. Per gram of tissue the spleen had the highest red blood cell volume after bleed-out. The volume of red blood cells remaining in the spleen and kidney was the same as found by Riecke and Everett in unbled Nembutalized rats.
Effects of acute anoxia on cardiac contractility
Authors: Woods E. F. , Richardson J. A.
Published: December 2017

Ventricular contractile force and arterial blood pressures were measured in anesthetized, vagotomized dogs rendered hypoxic by respiration with 100% nitrogen. Marked increments in heart force and blood pressures were observed: a) during brief nitrogen exposure and b) during the period of reoxygenation following substitution of room air for nitrogen. Experiments in animals subjected to 1) bilateral adrenalectomy, 2) thoracic sympathectomy and 3) total preganglionic sympathetic block indicate that the responses to acute oxygen lack are mainly due to stimulation of the sympathetic nervous system, while the responses to reoxygenation are dependent upon both the adrenal medullae and the sympathetic nerves.
Gamma-aminobutyric acid: a substrate for oxidative metabolism of cerebral cortex
Authors: McKhann Guy M. , Tower Donald B.
Published: December 2017

Oxygen uptake of slices of cat cerebral cortex, which have been preincubated without substrate, is supported by subsequent addition of γ-aminobutyric acid or succinic semialdehyde to an extent comparable to that by glucose or l-glutamic acid. Esterification of phosphate by cat cortex mitochondria is also supported by γ-aminobutyric acid or succinic semialdehyde, which yielded P/O ratios between 2 and 3, similar to ratios obtained with pyruvate or l-glutamic acid. The relevance of these findings to functional activity of the brain is discussed particularly in reference to seizure states, where metabolic abnormalities of glutamic acid and γ-aminobutyric acid occur, and to the physiological roles which have been proposed for γ-aminobutyric acid. It is suggested that cerebral energy metabolism may in part depend upon oxidative metabolism via the glutamic-γ-aminobutyric acid pathway, which could regulate a portion of the available energy and thus affect levels of functional activity.
Effects of controlled progressive hypotension on some spinal reflexes in the cat
Authors: Kissel John W. , Domino Edward F.
Published: December 2017

In the unanesthetized spinal cat at normotensive levels the crossed extensor reflex appeared considerably more variable than the patellar reflex. Both reflexes failed progressively as blood pressure was lowered but became hyperexcitable and were accompanied by convulsions at mean arterial pressures of 20–40 mm Hg. The crossed extensor reflex was more affected by hypotension than the patellar reflex. These reflexes disappeared under continued severe hypotension and recovered upon restoration of blood pressure to normal. Supplementary observations on spinal and intact cats under chloralose anesthesia indicated that the patellar reflex was more affected at less severe hypotensive levels in animals with an intact cerebrospinal axis.
Simultaneous flux of sodium into and out of the dog intestine
Authors: Berger Eugene Y. , Kanzaki Grace , Homer Mary A. , Steele J. Murray
Published: December 2017

The simultaneous unidirectional flow of sodium into and out of isolated loops of jejunum, ileum and colon of the dog, has been measured, in vivo. Four loops of bowel observed over a 5-year period did not degenerate physiologically or histologically. The variability of sodium flux, measured repeatedly over the five years, was no greater in experiments conducted 1 day apart than in those conducted over a period of years. Adrenalectomy did not reduce this inherent variability. Moderate salt loading by intravenous administration, or by dietary intake, did not alter the transfer rates of sodium across the intestine. Approximately 1 ml of water was transferred into and out of a 20-cm length of intestine/min. Sodium concentration was usually maintained at 144 mEq/l. in the lumen of the small intestine, while sodium concentration in the lumen of the large intestine usually decreased to be partially replaced by potassium. It is suggested that the rates of sodium flow across the dog intestine, in vivo, are of the same order of magnitude per unit surface area as those of sodium flux across amphibian tissues, in vitro. While water may enter the amphibian tissue 50 times as fast as sodium, water and sodium traverse the dog intestine in the ratio of their free diffusion coefficients, water moving twice as fast as sodium.
Effect of cancer and fasting on oxidation of labeled acetate, glucose and glycine to C14O2
Authors: Harmon Denham H. , Kirk Martha R. , Tolbert B. M.
Published: December 2017

Acetate-2-C14, glucose-C146 and glycine-2-C14 metabolism was studied in rats as a function of fasting and tumor growth. So measured, acetate metabolism was not affected, glucose utilization was at first depressed and later showed a moderate increase. Glycine was conserved in the tumor-bearing rat during the period of weight gain, but oxidation to CO2 markedly increased during weight loss in both the fasted and tumorous animals. The glycine and glucose rate curves all showed a delay of the peak specific activity time with fasting, presumably a result of depressed intermediary metabolic rates.
Quantitative relationship of antagonistic and inhibitory activities of certain adrenal steroids in an in vitro biological system
Authors: Hartman John D. , Gordon William F.
Published: December 2017

The in vitro effect of hydrocortisone, desoxycorticosterone and aldosterone has been studied in an isolated biological system. The system involved the quantitation of the leucocyte agglutination that occurs spontaneously when blood leucocytes are incubated. At critical hormone concentrations hydrocortisone inhibited whereas desoxycorticosterone and aldosterone stimulated the process. At higher concentrations the effects of hydrocortisone and desoxycorticosterone reversed. The stimulation of leucocyte agglutination by aldosterone and desoxycorticosterone can be inhibited by critical concentrations of hydrocortisone.
Measurement of hepatic glucose output and hepatic blood flow in response to glucagon
Authors: Shoemaker William C. , Van Itallie Theodore B. , Walker William F.
Published: December 2017

Arterial, portal and hepatic venous glucose concentrations and hepatic blood flow were simultaneously measured in nine dogs in the postabsorptive state, and after intravenous administration of glucagon. A marked rise in hepatic venous glucose concentration occurred promptly after glucagon administration. This rise coincided with a mean increase in estimated hepatic blood flow of approximately 100%. This increase in hepatic blood flow following the administration of glucagon was regularly observed in all animals; the increase in blood flow ranged from 41 to 204% in this series. Hepatic glucose output was calculated by multiplying the portal-hepatic vein gradient by the hepatic blood flow. The mean hepatic glucose output of the series increased from base line of 73 mg/min. to a maximum of 381 mg/min. in response to glucagon.
Effects of altitude acclimatization on rat myoglobin. Changes in myoglobin content of skeletal and cardiac muscle
Authors: Anthony Adam , Ackerman Eugene , Strother G. K.
Published: December 2017

Analyses were made of myoglobin content of rat skeletal and cardiac muscle following continuous exposure to simulated altitudes of 18,000 feet for a 2–10-week period. About five dozen rats were used. Acclimatization was associated with an increase in the myoglobin concentration of thigh, diaphragm, gastrocnemius and heart muscles. Total myoglobin content, however, increased during acclimatization in cardiac muscle but not in the three skeletal muscles. This finding together with the body weight changes and muscle weight changes suggested that the increases in myoglobin concentration of skeletal muscle may be merely a reflection of a decreased water content of muscles.
Effect of cold exposure on resistance to hemorrhage in dogs
Authors: Kuhn Leslie A. , Page Lot B. , Turner John K. , Frieden Julian
Published: December 2017

Effects of progressive hemorrhage during severe cold exposure were studied in 17 unanesthetized dogs. The amount of blood required to be withdrawn to reduce the mean arterial blood pressure to 50 mm Hg by a standardized bleeding procedure was determined in the same animals at air temperatures of +25°C and –25°C. Cold-exposed dogs showed a statistically significant increased ‘resistance’ to hemorrhage in that an average withdrawal of 20% more blood was required to reduce mean arterial blood pressure to shock levels in the cold than in the same dogs at comfortable temperature. In six animals it was necessary to draw a minor, but measurably greater, amount of blood from a given dog to produce hypotension during cold exposure than when the procedure was performed at a comfortable temperature and, in two animals, a minor, but measurably less, amount of blood was withdrawn during cold exposure. In seven animals a significantly greater amount of blood was drawn in the cold than in a neutral environment, but in some of these animals the control bleeding was apparently substandard. In two animals the control bleedings were in the normal range and bleedings were substandard in the cold. Cortisone administration did not alter resistance to hemorrhage during cold exposure.
Ventricular changes associated with sympathetic augmentation of cardiovascular pressure pulses
Authors: Kelso Albert F. , Randall Walter C.
Published: December 2017

Electrical excitation of the sympathetic innervation of the heart elicits marked increase in force of contraction of both ventricles which in turn produce augmented arterial pressure pulses. These pulses are characterized by a shortened isometric contraction period, a steeper rise in the systolic ejection phase, and a relatively greater rise in systolic than in diastolic pressure. Cardiometer tracings reveal an increase in both the rate and volume of systolic ejection, smaller end-systolic volume, with no significant change in end-diastolic volume. Stimulation during isovolumetric conditions in the ventricles reveals that such augmentation is primarily dependent upon changes in contraction of the myocardium and not upon alterations in peripheral resistance or in initial distention of the ventricles. Augmentation of systemic arterial pulses is immediately sustained by appropriate adjustments in venous return from the pulmonary vascular bed. Prolonged augmentation demands similar adjustments in venous return to the right heart and the pulmonary bed.
Constancy of stroke volume in ventricular responses to exertion
Authors: Rushmer Robert F.
Published: December 2017

Diastolic and systolic dimensions of the left ventricle and the free wall of the right ventricle in intact dogs are affected little by spontaneous exercise. The concept that stroke volume and heart rate in normal man increase by about the same relative amounts was derived from estimations of cardiac output, particularly in athletes, based upon indirect measurements using foreign gases or CO2. Data for man obtained with the modern cardiac catheterization or indicator dilution techniques confirm the impression derived from intact dogs that increased stroke volume is neither an essential nor a characteristic feature of the normal cardiac response to exercise. Stroke volume undoubtedly increases whenever cardiac output is increased with little change in heart rate (e.g. in athletes or in patients with chronic volume loads on the heart). Tachycardia produced experimentally with an artificial pacemaker in a resting dog causes a marked reduction in diastolic and systolic dimensions and in the stroke change of dimensions. The factors generally postulated to increase stroke volume during normal exercise may prevent the reduction in stroke volume accompanying tachycardia.
Histamine metabolizing activity of the stomach and intestine of the rat
Authors: Kobayashi Yutaka , Ivy A. C.
Published: December 2017

The squamous and glandular stomach and the small intestine of rats were studied for histamine-metabolizing activity, using 1 µg of C14-histamine as the substrate. The intestinal mucosa which contains much diamine oxidase (DO) (histaminase) was used as a control tissue. The squamous stomach metabolized approximately 70%; the glandular stomach, 40%; and the small intestine, 92% of the histamine. After adding the DO inhibitors, aminoguanidine and semicarbazide, to the minced tissue digest of all three tissues, approximately 12% of the histamine was still destroyed or unaccounted for.
Mechanical and electrical activity in intestinal smooth muscle
Authors: Sperelakis Nick , Prosser C. Ladd
Published: December 2017

Rings of ganglion-free circular muscle from cat intestine show, in addition to circling conduction, waves which are transmitted along the long axis of the intestine at about 0.7 cm/sec. and in bands about 1.2 mm in width. Evidence against the mechanical pull hypothesis for transmission include the facts that strips of the circular muscle do not respond to brief stretches, conduction may occur through a clamped region which does not pass a mechanical wave, electrical responses may persist under tensions at which shortening does not occur, and drugs may cause some dissociation of electrical and mechanical responses. It is concluded that conduction is independent of mechanical pull. Intracellular electrodes recorded resting potentials with a mean value of 40 mv, conducted action potentials with a mean of 22 mv. Conducted responses fail to follow at intervals less than about 1 second, whereas single fibers may give multiple responses 0.3 seconds apart and double spikes only 40 msec. apart.
Effect of growth hormone and thyroxine on growth and chemical composition of muscle, bone and other tissues in thyroidectomized-hypophysectomized rats
Authors: Scow Robert O.
Published: December 2017

Rats were thyroidectomized-hypophysectomized at weaning and 5 weeks later treated for 36 days with either growth hormone (0.1 or 0.5 mg/day), thyroxine (2.5 µg/day), or both. Growth hormone stimulated growth of all tissues whereas thyroxine accelerated growth of only muscle and certain viscera. The growth response of some tissues to thyroxine was as pronounced as that to growth hormone. Administration of thyroxine increased the response to growth hormone of only the tissues that grew when thyroxine was given alone. Although thyroxine had no effect on the amount of bone protein in growth hormone treated and untreated rats, it had a pronounced effect on the morphology (length and maturation) of bone. The amount of collagen in muscle increased with dosage of growth hormone; thyroxine had no effect on this response. Myosin, on the other hand, increased with growth hormone dosage only in those animals also given thyroxine. Thyroxine given alone increased myosin deposition in muscle but had no effect on collagen in muscle, bone or skin.
Cardiovascular effects of levarterenol, hydrocortisone hemisuccinate and aldosterone in the dog
Authors: Small Harold S. , Weitzner Stanley W. , Nahas Gabriel G.
Published: December 2017

Ten Starling heart-lung preparations were given levarterenol, either as a single 5 µg dose or as a 2-minute infusion (5 µg/min.), while cardiac output and blood pressure were measured. A repeat dose 15–20 minutes after administration of 10 mg of hydrocortisone evoked a quantitatively similar response. Failure to observe potentiation in normal heart-lung preparations led to the use of bilaterally adrenalectomized dogs (maintained until 48 hr. prior to testing on cortisone acetate or DCA in oil), both as blood donor and preparation animal. In four such preparations similarly tested, no potentiation was observed. The blood pressure response to levarterenol was next tested in the intact dog. Two dogs were tested under local anesthesia with single 30-µg doses, and a third was tested with an infusion (5 µg/min.) while under light Nembutal anesthesia. Thirteen adrenalectomized dogs (maintained until 24 hr. prior to testing only on DCA in oil) were further tested under various conditions: either awake or anesthetized (either ventilated with 100% oxygen, or breathing spontaneously); either with a single dose (1–30 µg) or with a constant infusion (30–50 µg/kg/hr.). The response of all animals to levarterenol was unchanged after the administration of hydrocortisone or of aldosterone. It was further noted that all animals maintained a constant blood pressure response during the 10–90-minute period of levarterenol infusion before administration of hydrocortisone.
Cortisol and citrate metabolism
Authors: Harrison Helen C. , Harrison Harold E.
Published: December 2017

Determinations of citrate concentrations in serum and tissues were made in fluoroacetate-injected rats given cortisol. The increment of serum citrate is less in the cortisol treated rats than in controls injected with fluoroacetate, but the accumulation of citrate in heart and small intestine following fluoroacetate is equally great in both groups. Lower concentrations of citrate in the kidneys of cortisol-treated rats are probably due to differences in citrate of tubular urine. In the adrenalectomized rat fluoroacetate causes a greater rise of serum citrate than in the intact rat but there is no greater increase of tissue citrate. Calculation of citrate distribution ratios, i.e. the ratio of the concentration of citrate in intracellular water to that of extracellular fluid, indicates that the distribution ratio following fluoroacetate is increased by cortisol and decreased by adrenalectomy. Cortisol does not apparently influence the intracellular accumulation of citrate but alters the distribution of citrate between cells and extracellular fluid, possibly due to an effect upon the efflux of citrate from cells.
Conjugation and excretion of the amino and acetamido benzoic acids
Authors: Knoefel P. K. , Huang K. C. , Despopoulos A.
Published: December 2017

The conjugation of the aminobenzoic acids with glycine and glucuronic acid has been measured in the rabbit and the dog. In both species the total conjugation is greatest with the ortho isomer, least with the para. In the rabbit, the amount of hippurate formed is greater than the amount of glucuronide formed, and in each case, greatest with the ortho isomer and least with the para. These relations are determined by the comparative first-order reaction rates, the comparative zero-order reaction rates, the concentration of the aminobenzoic acid in the body at which the reaction changes from first-order to zero-order, and the dose. In the dog, the meta aminobenzoic acid forms more hippurate than glucuronide, as in the rabbit, but for the ortho and para isomers the formation of hippurate is much less than that of glucuronide. The meta and para acetamidobenzoates are conjugated to a smaller extent than are the aminobenzoates. Slices of kidney and liver perform these conjugations to an extent agreeing with that in the whole animal, in some but not all cases. It appears that both species form the three hippurates in the kidney, but in the liver by the rabbit only. Both species form the three glucuronides, probably in both kidney and liver.
Effect of insulin on hepatic blood flow in the unanesthetized dog
Authors: Shoemaker William C. , Mahler Robert , Ashmore James , Pugh Daniel E.
Published: December 2017

The immediate and direct effect of intravenously or intra-arterially administered insulin upon hepatic blood flow was studied in unanesthetized dogs whose hepatic vessels had been previously catheterized. Comparison was made between two dose levels, 0.1 or 0.2 u/kg and 1.0 u/kg, the latter being infused over a 30-minute period. At the 0.1 or 0.2 u/g range there was no immediate statistically significant flow increase. Sporadic flow increases occurred in about half the series during the recovery phase of the hypoglycemia (20–45 min. after insulin). At the 1.0 u/kg level insulin produced a definite increase in HBF which reached its maximum at 15 minutes. These flow changes were interpreted as secondary effects to the insulin induced hypoglycemia.
Effect of epinephrine on glycogen stores
Authors: Sokal Joseph E. , Sarcione Edward J.
Published: December 2017

Subcutaneous epinephrine doses of 0.1 mg/kg or more consistently produced declines in muscle glycogen of rats. Transient declines (30%) in liver glycogen, followed by net resynthesis to levels above the control value, were observed after subcutaneous doses 0.2–0.4 mg/kg. Subcutaneous doses of 6.0 mg/kg were required to produce progressive depletion of liver glycogen (82%), over a 3-hour period. However, such depletion was uniformly obtained by intraperitoneal injection of much smaller doses (0.4 mg/kg/hr.). High blood levels of lactate and glucose did not reverse glycogenolysis in liver or in muscle when adequate concentrations of epinephrine were maintained. Although intraperitoneal injection of epinephrine leads to high concentrations at the liver and lower concentrations at skeletal muscle, intraperitoneal doses of 0.1 mg/kg/hr. produced declines in muscle glycogen but not in liver glycogen. It is concluded that the concentration of epinephrine required to produce glycogenolysis in the liver is at least 5–10 times as high as that effective in the muscle. The transient hepatic glycogenolysis observed after relatively small subcutaneous doses of epinephrine may be due to stimulation of endogenous glucagon release.