bluuebunny/crossref_metadata_2025 huggingface dataset:
The Subcomissural Organ: A Regulator of Thirst
Authors: Gilbert Gordon J.
Published: December 2017

Electrocoagulative destruction of the subcommissural area in rats results within a few days in death due to dehydration. Subcutaneous injection of aqueous extracts of rat or beef subcommissural area into rats resulted in sharp depression of water consumption, with a rise in intake on the 2nd day. Control injections employing extracts of rat or beef cerebrum failed to alter water intake. Twenty-five hundredths per cent acetic acid destroys this hormonal activity, as does shaking with ether or petroleum ether. It is suggested that the active substance may be a large, readily denatured protein. When these subcommissural extracts were injected into either adrenalectomized or hypophysectomized rats, the response differed markedly from that observed in normal animals. Intake of water fell 40–50% on the 1st day and there was no return to normal levels of water consumption on the 2nd day, but recovery, if it occurred, was a gradual process.
Adipsia and Aphagia in Rats After Lateral Subthalamic Lesions
Authors: Morrison Seoras D. , Mayer Jean
Published: December 2017

Localization of lesions in the lateral subthalamic area of rats which produce a high success rate of aphagia is described. Complete adipsia accompanied this aphagia in all cases. The aphagia and the adipsia are separate responses to the lesion. The pattern of material exchange cannot be reproduced by deprivation of sham-operated rats of either food or water. Rats fully sham operated in this area show hypophagia and hypodipsia for 1 or 2 days after operation. Daily intubation of water into operated animals appears to facilitate the escape of animals from the inhibition of eating and drinking. Escaped animals showed a pronounced polydipsia after escape, but this was of a variable degree of permanence and did not always appear consistent in other respects with diabetes insipidus.
Effect of Sham Operations in the Hypothalamus on Food and Water Intake of the Rat
Authors: Morrison Seoras D. , Mayer Jean
Published: December 2017

Exploratory electrode insertions using a stereotaxic instrument, without passing current, have been made bilaterally in and around the area in the hypothalamus of the rat where electrolytic lesions produce complete aphagia and adipsia. These ‘sham operations’ produce pronounced hypophagia and hypodipsia for 1–2 days. Effect on food intake is large and fairly uniform with all insertions peripheral to these nuclei but increases abruptly in the immediate neighborhood of the nuclei. It is suggested that electrode insertion without passing current may be useful as a finer tool than electrolytic lesions for precise localization of the centers involved.
Alterations in Systemic Vascular Volume of the Dog in Response to Hexamethonium and Norepinephrine
Authors: Rose John C. , Freis Edward D.
Published: December 2017

A diaphragm pump of controlled constant output was substituted for the left ventricle in dogs. Left auricular blood was conducted to a reservoir, from which it was pumped into the thoracic aorta. Left ventricular by-pass was complete. Alterations in total vascular volume were continually monitored by observation of the pump reservoir level. Sympathetic blockade (hexamethonium) increased total vascular volume (mean 15%). This resulted in decreased venous return and decreased right ventricular output. Norepinephrine constricted the total vasculature and decreased vascular volume (mean 12%). This resulted in increased venous return and cardiac output. These experiments demonstrated the complex integrated responses of the total circulation to sympathetic vasomotor activity. The role of the sympathetic nervous system not only in the regulation of arteriolar tone and cardiac activity but also in adjusting total vascular volume and venous return was emphasized. Venous return, and hence cardiac output alterations accompanying systemic vasomotor activity can only be detected by continuous methods of flow measurement.
Hypoglycemia in Dogs and Recovery After Intracisternal Administration of Glucose
Authors: Doyle Miles L. , Olsen Norman S.
Published: December 2017

A standardized procedure for the production of hypoglycemia in dogs has been developed. The degree of hypoglycemia may be determined by the correlation of electroencephalographic tracings and levels of plasma constituents. During severe hypoglycemia glucose was injected either by the intravenous or intracisternal route. In the former group the brain electrical activity returned to normal within 1 minute, whereas, the latter group required 6–10 minutes. Serial sampling of arterial blood in the animals which had been given glucose directly into the cerebrospinal fluid showed that relatively large increases in plasma glucose preceded the return to normal electrical activity of the brain. It is concluded that glucose does not pass directly from the cerebrospinal fluid into the cerebral tissues but rather is transported to the general circulation before entering the brain.
Action of Mephentermine on Arrhythmias Due to Pulsus Alternans, Rapidly Discharging Single Atrial Foci and Prolonged P-R Intervals
Authors: Oppenheimer M. J. , Lynch P. R. , Ascanio G.
Published: December 2017

Slow conduction velocities play a role in pulsus alternans and digitalis intoxication and possibly in the arrhythmia due to a rapidly discharging atrial aconitine focus. In the ventricle mephentermine increases conduction velocity, shortens refractory period and A-V conduction time. The present study investigates the usefulness of mephentermine in these conditions. Pulsus alternans was reverted to a normal series of mechanical contractions by mephentermine. The same agent provided periods of regular rhythm during the presence of an atrial aconitine focus; in two cases a permanent sinus rhythm was established. The prolonged P-R interval due to intoxication with acetyl strophanthidin was restored to normal by mephentermine. The action of mephentermine is specific since compounds with addition or subtraction of one methyl group or the hydroxy-mephentermine were ineffective against a circus flutter.
Relation of the Saluresis of Urea and Mannitol Loading to the Normal Excretion of Electrolyte
Authors: West Clark D. , Bayless Ruth K.
Published: December 2017

In hydrated dogs subjected to mild solute diuresis with mannitol and urea, the patterns of change in the course of the experiments in the ratios of sodium and chloride excretion to total solute excretion were not significantly different from those observed in control experiments conducted in an identical manner but in which no solute load was imposed. In hydrated, mildly acidotic dogs a similar result was obtained if only the mean values of the data are considered; in individual experiments loading produced considerable fluctuations in the ratios as compared with control experiments. Hydropenic animals, on the other hand, showed an increase in the sodium:total solute ratio with loading but the chloride:total solute ratio was not significantly affected. The potassium: total solute ratio was, in general, also independent of solute diuresis. In the hydropenic and hydrated acidotic animals the ratio was unaffected by loading but in the hydrated nonacidotic animals, considerable variability in excretion made interpretation of the ratios difficult. Ratios calculated in a similar manner for titratable acid, ammonia, bicarbonate and phosphorus all fell with loading. Reductions in filtration rate occasioned by urea loading had no effect on the ratios for sodium, potassium and chloride. The data appear to provide a link between the saluresis of solute loading and the normal excretion of electrolyte and suggest that the saluresis is simply a magnified operation of the normal mechanism concerned with electrolyte. The ratio of electrolyte to total solute would appear to be of physiological significance, differing from other parameters of electrolyte excretion in that it is independent of at least moderate fluctuations in the rate of nonelectrolyte excretion.
Potentiation of Renoprival Hypertension by Alanine, Pyruvate and Lactate
Authors: Muirhead E. E. , Jones F. , Stirman J. A.
Published: December 2017

An assay procedure for the evaluation of renoprival hypertension without the use of dialysis is presented. The arterial pressure is taken twice daily for 4–7 days in the intact animal. Both kidneys are removed and subsequently the arterial pressure is taken twice daily. Each day the animal is given about 2 mEq of sodium/kg in 16 ml volume/kg. To this is added daily the dietary or other ingredient which is being evaluated. A group of 28 dogs receiving protein in the diet developed a significantly greater hypertension when compared to a group of 31 dogs receiving no protein. When compared to these two control groups a group receiving alanine in the diet (10 dogs) and two additional groups receiving pyruvate (15 dogs) and lactate (12 dogs) parenterally revealed evidence for potentiation of renoprival hypertension by these compounds.
Mechanism of the Increased Venous Return and Cardiac Output Caused by Epinephrine
Authors: Guyton Arthur C. , Lindsey Arthur W. , Abernathy Berry , Langston Jimmy B.
Published: December 2017

The effect of epinephrine on venous return has been measured in 11 dogs under total spinal anesthesia. The mechanism by which epinephrine increases venous return seems to be to increase the tone of the vascular walls thereby increasing the mean circulatory pressure. This in turn increases the pressure gradient forcing blood from the systemic vessels toward the right atrium. By equating the recorded venous return curves with curves that depict the effect of epinephrine on the heart's ability to pump blood, it is shown that under normal operating conditions cardiac output is determined far more by the tendency for blood to return to the heart than by the heart's ability to pump blood.
Performance Characteristics and Oxygen Debt in a Nonfailing, Metabolically Supported, Isolated Heart Preparation
Authors: Sarnoff S. J. , Case R. B. , Welch G. H. , Braunwald E. , Stainsby W. N.
Published: December 2017

Performance characteristics, stability and ventricular function curves were studied in an isolated heart preparation in which the metabolic state of the perfusing blood was kept at or near normal by continued exchange with a supporting dog. In contrast to the progressive failure exhibited by the classical isolated heart or heart-lung preparations, the isolated supported heart's performance did not differ from the performance of the heart in an open-chest, anesthetized dog with a complete circulation. Myocardial O2 consumption could be determined with a high degree of precision. O2 debt comparable to that which occurs in skeletal muscle was not observed.
Hemodynamic Determinants of Oxygen Consumption of the Heart With Special Reference to the Tension-Time Index
Authors: Sarnoff S. J. , Braunwald E. , Welch G. H. , Case R. B. , Stainsby W. N. , Macruz R.
Published: December 2017

The hemodynamic determinants of myocardial oxygen utilization were ascertained in the isolated, metabolically supported, nonfailing canine heart. The primary determinant was found to be the total tension developed by the myocardium as indicated by the area beneath the systolic pressure curve (Tension-Time Index). The significance of these findings for the understanding of the low efficiency of the failing heart and the consequently increased importance of Laplace's law are discussed.
Renal and Cardiovascular Effects of Anesthetic Doses of Pentobarbital Sodium
Authors: Blatteis Clark M. , Horvath Steven M.
Published: December 2017

The renal and cardiovascular effects of anesthetic doses of pentobarbital sodium were investigated in eight trained, postabsorptive, female dogs. Glomerular filtration rate, renal blood flow, and certain tubular functions remained unchanged during the unanesthetized and anesthetized states. Except for a brief period during induction, the blood pressure likewise was unaffected by the anesthesia. The heart rate increased significantly in the immediate postanesthetic period, but had regained control levels after 30 minutes. The hematocrit was unaltered by the pentobarbital action. The conflicting results which have been reported on the influence of this anesthetic agent on renal and cardiovascular functions can most probably be attributed to the variability in experimental conditions employed.
Pressure-Flow Relationships in the Dog Lung During Acute, Subtotal Pulmonary Vascular Occlusion
Authors: Lategola Michael T.
Published: December 2017

The relationship of pulmonary artery pressure to pulmonary blood flow was studied in the dog by means of occlusive shifting of blood flow within the pulmonary vascular bed. All experiments were performed using the closed-chest preparation. The range of blood flow increases studied was 25–388%. A graphical plot of the percentage change in blood flow versus the percentage change in mean pulmonary artery pressure is presented. A visually estimated curve of this latter data is presented, discussed and compared to four other curves from previous pulmonary vascular studies. A comparison of these curves suggests that the relative maximum capacity of the pulmonary vascular bed of man and dog are similar. These curves plus certain assumptions allow the speculative delineation of a graphical area representing the ‘active’ vasomotor component of exercise at different levels of pulmonary blood flow increase.
DC Potentials of the Membranous Labyrinth
Authors: Smith Catherine A. , Davis Hallowell , Deatherage Bruce H. , Gessert Carl F.
Published: December 2017

The endolymphatic DC potentials were measured in the utricle, saccule and cochlear duct of the membranous labyrinth of the guinea pig and compared with potassium analyses of the endolymph. The average utricular potential was found to be +4 mv, the saccular potential +1 mv, and the cochlear potential +65 mv. The average potassium concentration of utricular endolymph was 139 mEq/l.; that from the cochlea was similar. The cochlear DC potential is approximately 70 mv higher than that of the vestibule (utricle and saccule), whereas the high potassium and low sodium concentration of endolymph is similar throughout. It is concluded that the endolymphatic resting potential of the internal ear is not correlated with the potassium or the sodium concentration of the endolymph.
Lasting Behavioral and EEG Changes in Cats Induced by Prolonged Stimulation of Amygdala
Authors: Alonso-deFlorida Francisco , Delgado José M. R.
Published: December 2017

Social behavior of a colony of eight cats was recorded by time-lapse photography. A picture was taken every 9 seconds for 10 hours daily. Direct observations were also made. Films were analyzed, noting the time spent by each animal in selected patterns of behavior. Permanent cerebral electrodes were implanted in 15 cats and different areas stimulated for half a second every 5 seconds for 1 hour daily for 1–15 days. This type of prolonged stimulation of amygdala increased playful and contactual activities, modified aggressive and sexual behavior and produced other somatic, autonomic and behavioral effects. Local electrical activity was also influenced and seizure-like patterns were persistently recorded. Both behavioral and EEG phenomena were reversible (with 2 exceptions) and reproducible. Similar prolonged stimulation of other cerebral structures (internal capsule, falx cerebri and anterior hypothalamus) did not produce significant results.
Changes in Intestinal Net Absorption of a Sodium Chloride Solution Produced by Atropine in Normal and Vagotomized Dogs
Authors: Tidball C. S. , Tidball M. E.
Published: December 2017

Net absorption of 1% NaCl was studied in acute experiments in dogs anesthetized with sodium pentobarbital. In dogs with intact vagi, net absorption was increased by atropine and then decreased below the preatropine level before returning to that level in approximately 1 hour. In dogs with complete bilateral vagotomies, net absorption was increased by atropine and there was no decrease below the preatropine control level; 1 hour following the injection of atropine the net absorption was still significantly elevated. In dogs with vagi intact or sectioned, increased net absorption following atropine is explained, in part if not entirely, by a depression of secretion. That atropine can produce changes in secretion in vagotomized dogs indicates that acetylcholine produced by intrinsic mechanisms is capable of stimulating secretion in the small intestine. In dogs with intact vagi, decreased net absorption following the increased net absorption is believed to be due to a decrease in true absorption. That this decreased net absorption is not observed in the vagotomized dog is evidence that the vagus exerts a stimulatory influence on true absorption.
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

Elimination of radioiodide by the kidney of adult male rats pretreated with a single dose of propylthiouracil was measured. Rats given water or isotonic saccharose served as controls. Renal clearance of radioiodide (CI131) was greatly enhanced (up to 100-fold) by the sodium salts of chloride, perchlorate, stable iodide, bromide and bicarbonate, and by choline iodide, but not by sodium thiosulfate. Under most conditions CI131 markedly exceeded the CCl and CNa of the same animals, which suggest that renal tubules are less permeable to iodide than to chloride or sodium. CI131/CNa varied greatly, its magnitude being dependent on the loading solution used. CI131 showed no correlation with urine flow or excretion of endogenous creatinine-like chromogen (UCrV) when groups receiving different treatments were compared. Both urine flow and UCrV showed only minor variations among these groups. Our findings are most easily explained by the hypothesis that tubular reabsorption of iodide filtered by the glomeruli involves, possibly in addition to a passive process, an active transport mechanism capable of saturation by iodide and (competitive?) inhibition by other anions.
Effect of Prolonged Consumption of Pemmican Survival Ration on Some Aspects of the Intermediary Metabolism of Rat Liver Tissue
Authors: Hannon John P. , Vaughan David A.
Published: December 2017

The effect of prolonged feeding (3–5 months) of pemmican on some aspects of the in vitro metabolism of liver tissue was investigated. The endogenous metabolism of liver slices and homogenates was significantly increased by pemmican, probably due to an increase in the amount of readily metabolizable substrate. Utilizing mitochondrial preparations, it was found that with all substrates studied, except glutamate, α-ketoglutarate and succinate, the respiratory rate was not affected by the previous diet in the absence of added cytochrome c and diphosphopyridine nucleotide. The three substrates mentioned were oxidized at significantly lower rates in the pemmican group. Upon the addition of cytochrome c and diphosphopyridine nucleotide the qo2 of glutamate, α-ketoglutarate, and succinate was returned to the normal value.
Graded and Decremental Response in Heart Muscle Fibers
Authors: Kao C. Y. , Hoffman Brian F.
Published: December 2017

Simultaneous records of the transmembrane potential from two points in a single cardiac fiber indicate that during the refractory period when repolarization is about half complete graded responses appear close to the site of stimulation. These responses to cathodal pulses vary in amplitude with stimulus intensity and may show spatial decrement even when an overshoot is present close to the stimulating electrode. The results obtained indicate that the transition from graded to all-or-none response does not depend solely on the restoration of membrane potential. In some experiments stimulation was accomplished by employing one lumen of a double microelectrode; in others single Purkinje fibers were stimulated by action potentials propagated from attached papillary muscle. Similar graded responses were elicited in both instances. The experiments employing propagating action potentials as stimuli suggest the possible occurrence of graded activity as a response mechanism in the intact heart.
Oxygen Consumption, Body Temperature and Heart Rate of Woodchucks Entering Hibernation
Authors: Lyman Charles P.
Published: December 2017

Oxygen consumption, heart rate and temperatures from various parts of the body were measured in woodchucks ( Marmota monax) entering hibernation. Comparisons were made with the chilling of woodchucks anesthetized with sodium pentobarbital, with and without the ganglionic blocking agent bis(trimethylammonium)hexane dibromide. Heart rate and oxygen consumption began to decline before any drop in body temperature as animals entered hibernation. The process was usually not continuous, for periodically the heart speeded, oxygen consumption and muscle action potentials increased and, shortly thereafter, the temperature rose transiently with the anterior portion of the body warming faster than the posterior. These partial rewarmings were less and less frequent as the total period of hibernation became longer. As hibernators chilled, the heart was the warmest area, with the thorax warmer than the abdomen. Dead woodchucks curled in the hibernating position chilled faster than the hibernators with the central portion of the abdomen chilling the slowest. In the supine, anesthetized animal, with or without the ganglionic blocking agent, the flow of blood altered the chilling so that the area near the heart remained slightly warmer than the abdomen. If curled in the hibernating position, the heart region remained much warmer than the abdomen because blood flow was curtailed by the restricted position. Chilling of the hibernator was identical to the curled, anesthetized animal except that the thoracic region of the former remained warmer due to periodic rewarmings, and also shivering in this well-muscled area. It is concluded that entrance into hibernation is not strictly temperature-dependent and that the animal is vasodilated during this process.
Renal Regulation of Urea Excretion in Sheep
Authors: Schmidt-Nielsen Bodil , Osaki Humio , Murdaugh H. V. , O'Dell Roberta
Published: December 2017

In order to elucidate the renal mechanism for the regulation of urea excretion the urea clearance and the GFR were studied in sheep during normal and low protein intake in a range of urine flows from extreme osmotic diuresis to minimal flows. Differences in the effects of osmotic and water diureses and the effects of abrupt changes in rate of urine flow were also studied. In sheep on normal protein intake the urea/inulin clearance ratio was constant in the range of urine flows corresponding to inulin U/P ratios from 10 to 500. On low protein intake the urea/inulin clearance ratio decreased markedly with decreasing urine flow. At extremely high urine flows no difference was found between the urea/inulin clearance ratios on different diets. Regulation was found to be independent of GFR, plasma urea concentration and osmotic load and must therefore be on the tubular level. Observations during abrupt changes in urine flow showed that the urea clearance is not only abnormally high during increasing flows but also abnormally low during a sudden decrease in flow. The first phenomenon is known as ‘exaltation,’ and we have termed the latter phenomenon ‘abatement.’ The data on exaltation and abatement and on the effects of urine flow are consistent with a previously suggested hypothesis that the excretion of urea in the mammalian kidney is brought about through a regulated active transport of urea, accentuated by a countercurrent multiplier system represented by Henle's loops and vasa recta.
Renal Conservation of Trimethylamine Oxide by the Spiny Dogfish, Squalus Acanthias
Authors: Cohen Julius J. , Krupp Marcus A. , Chidsey Charles A.
Published: December 2017

Trimethylamine oxide (Oxide) plasma concentrations in the dogfish have been found to be maintained within the narrow range of 60–80 µmol/ml. These levels are maintained in spite of prolonged (up to 41 days) fasting. The Oxide is freely filterable at the glomerulus but is avidly reabsorbed by the renal tubule. Thus, less than 10% of the filtered Oxide appears in the urine. Dogfish urine has been found to contain an unidentified volatile amine, not NH3, presumed to be trimethylamine. The possible role of the Oxide in elasmobranch physiology is discussed.
Effect of Blood Transfusion and Hemorrhage on Cardiac Output and on the Venous Return Curve
Authors: Guyton Arthur C. , Lindsey Arthur W. , Kaufmann Berwind N. , Abernathy Joseph B.
Published: December 2017

The effect of blood transfusion or hemorrhage on the venous return curve has been studied in 10 dogs with normal circulatory reflexes and in 10 additional areflex dogs. At all right atrial pressures transfusion increased the venous return and hemorrhage decreased it. Following transfusion the venous return remained elevated only transiently, returning progressively toward the control value during the ensuing 10–20 minutes. Following hemorrhage, however, the venous return remained depressed for prolonged periods of time. The same effects were observed after infusion of Tyrode's solution as after transfusion of blood.
Measurement of the pH of the Endolymph in the Cochlea of Guinea Pigs
Authors: Misrahy George A. , Hildreth Kenneth M. , Clark Leland C. , Shinabarger Edward W.
Published: December 2017

Using a potassium chloride reference microelectrode and an antimony-Cerroseal alloy active microelectrode, the pH of the perilymph exposed to the atmosphere was found to be 7.8–8.0 and the endolymph in situ 7.3–7.5 in the guinea pig. The acidity of these fluids in situ appears to be very sensitive to changes in carbon dioxide tension.
Exaggerated Ventricular Arrhythmias and Myocardial Fatty Changes After Large Doses of Norepinephrine and Epinephrine in Unanesthetized Dogs
Authors: Maling Harriet M. , Highman Benjamin
Published: December 2017

An intravenous infusion of a large dose (0.51 mg/kg) of norepinephrine sensitizes the heart to the action of catechol amines for a period of 2–4 days. During this period, small doses of either epinephrine or norepinephrine induce ventricular tachycardia. In dogs killed the day after infusion, frozen sections of the myocardium stained with Oil red O reveal fatty changes, the severity of which roughly parallels that of the induced tachycardias. Fatty changes were still present in the hearts of dogs killed the 3rd day after infusion, but were negligible 5 days after infusion. Similar, but less marked, cardiac effects were elicited by infusions of large doses of epinephrine.
Effect of Environmental Temperature on Diurnal Variation of Blood Constituents in the Bovine
Authors: Diven R. H. , Page H. M. , Erwin E. S. , Roubicek C. B.
Published: December 2017

Five yearling Hereford steers were maintained in the open sunlight for three sampling periods; each period separated by 7 days. Feed was withheld during the sampling periods and water was restricted throughout the second sampling period. Whereas total serum protein varied directly in a linear fashion, blood creatinine, plasma cholesterol and carotene showed an inverse relationship with environmental temperature. A consistent relationship existed between time of sampling and plasma carotene concentration. Statistical analyses failed to show a consistent relationship between sampling time or temperature and levels of uric acid and glucose.
Effect of Change in Renal Venous Pressure Upon Renal Vascular Resistance, Urine and Lymph Flow Rates
Authors: Haddy F. J. , Scott J. , Fleishman M. , Emanuel D.
Published: December 2017

The usual increase in intrarenal resistance as a function of flow rate was augmented by elevation of venous pressure. The augmentation was more apparent in innervated than denervated kidneys. With blood flow rate held constant, resistance increased as a function of venous pressure in innervated kidneys but decreased slightly in denervated kidneys. The latter response was not different during administration of phentolamine, phentolamine and eserine or during perfusion of live innervated and dead kidneys with dextran. Resistance changes induced by elevation of only arterial pressure were the same in innervated and denervated kidneys. For a given arterial pressure in dead kidneys perfused with dextran, resistance was higher with venous pressure elevated than it was with pressure normal. Lymph flow rate increased as a function of venous pressure. Urine flow rate decreased as a function of venous pressure with blood flow rate uncontrolled but did not change when flow rate was held constant. Therefore, high renal vein pressures increase resistance by reflex active vasoconstriction as well as by passive vasoconstriction. The reduction in urine flow rate is in part related to these resistance controlling mechanisms.
Metabolism of Unesterified Fatty Acids (UFA) in Normal Dogs
Authors: Roheim Paul S. , Spitzer John J.
Published: December 2017

The source and disappearance of plasma UFA were studied in normal dogs by simultaneous lipid determinations in blood samples from the femoral artery, femoral vein, portal vein and hepatic vein. Marked and consistent veno-arterial and frequent portal vein-arterial differences were found indicating UFA liberation in the leg and in the abdominal region, due to either lipolysis or mobilization from fat depots. Differences between UFA content of the portal and hepatic veins and of the portal vein and femoral artery were also consistent, showing uptake of UFA by the liver. The abdominal region also took up UFA frequently as indicated by arterial-portal differences. Similar changes were not detectable in triglycerides, total and free cholesterols and phospholipids.
Control of Secretion From the Avian Salt Gland
Authors: Fänge Ragnar , Schmidt-Nielsen Knut , Robinson Maryanne
Published: December 2017

In birds with a marine habitat the nasal glands are modified into salt glands, able to excrete excess sodium chloride. The nervous control of the salt glands was investigated in the herring gull, Larus argentatus. Normal secretion of the salt gland seems to be released by a nerve reflex involving higher nerve centers and central osmoreceptors. The reflex can be evoked experimentally by intravenous injection of a hypertonic NaCl solution or by increasing the osmotic pressure of the blood in other ways. The gland is innervated from a nerve plexus in the anterior part of the orbit of the eye. Secretion is produced by stimulation of a nerve, probably a branch of the VII cranial nerve, which connects with the plexus. The plexus also receives sympathetic fibers, but no secretion was observed after stimulation of the cervical sympathetic. The gland is stimulated to secrete its osmotically highly concentrated fluid (700–800 mm Na) by Mecholyl and acetylcholine, indicating a parasympathetic innervation as the normal excitatory pathway. The secretion that normally occurs in response to a salt load is blocked by anesthesia. It is also inhibited by atropine, adrenaline or acetazolamide (Diamox).
Growth of Normal and Thyroidectomized Rats on Iodine-Deficient Diet
Authors: Gemmill Chalmers L.
Published: December 2017

Thyroidectomized rats on an iodine-deficient diet have little or no growth. Inorganic iodide, 3,5-diiodothyronine and inorganic iodide with 3,5-diiodothyronine do not promote growth in these animals. On a normal diet, thyroidectomized rats have retarded growth. After considerable time of cessation of growth on the iodine-deficient diet, 3,3',5-triiodo-l-thyronine restores growth in the thyroidectomized animal. The cessation of growth in the thyroidectomized rats on iodine-deficient diet is considered due to the absence of metabolically active organic iodine which is present in the normal diet.
Oxidative Activity of Aortic Tissue of Man, the Rabbit and the Dog, With Special Reference to Succinic Dehydrogenase and Cytochrome Oxidase
Authors: Maier Nelicia , Haimovici Henry
Published: December 2017

Succinic dehydrogenase and cytochrome oxidase activities were determined in homogenates of three aortic segments (ascending and arch, descending thoracic, abdominal) and liver of man, the rabbit and the dog. Both enzymes exhibited the lowest activity in human aorta. Succinic dehydrogenase exhibited the highest activity in the thoracic aorta of the dog and intermediate activity in the latter's abdominal segment and the rabbit's aorta. Cytochrome oxidase, in contrast, exhibited the highest activity in the rabbit's aorta. A slight gradient of decreasing activity from thoracic to abdominal aorta was noted for cytochrome oxidase in both the rabbit and dog and for succinic dehydrogenase in the rabbit, whereas a significant decrease in the latter enzyme was noted in the abdominal segment of the dog. No gradient of activity was apparent in man. Liver exhibited the lowest activity for both enzymes in man, highest in the dog and intermediate in the rabbit. The above findings suggest a biologic species difference between the aorta of man, the rabbit and the dog, which may be partly ascribed to a difference in the components of the above two enzymatic systems. The same species difference holds true for hepatic tissue.
Comparative Effects of Parathyroid Extract and Turpentine Abscesses on the Serum Glycoproteins and the Polysaccharides of the Kidney
Authors: Shetlar M. R. , Howard R. Palmer , Joel Walter , Bowling Dorothy C. , Shetlar Clara L.
Published: December 2017

Studies were made of the time relationships existing between administration of parathyroid extract to rats, the elevation of serum glycoproteins and the deposition of polysaccharide and calcium in the kidney. Statistically significant elevations of seromucoid occured 18 hours after the injection of turpentine and 24 hours after the first injection of parathyroid extract. These data may indicate that the effects of parathyroid extracts and turpentine on seromucoid differ. Statistically significant elevations of the serum glycoproteins other than seromucoid occurred at 36 hours in both groups. The first histochemical changes in the kidney were noted 36 hours after the first injection of parathyroid extract. Intratubular lesions were noted which contained both calcium and material which stained with periodic-acid-Schiff reagent (PAS), colloidal iron and Alcian blue. Later (48 hr. after injection) another type of lesion which stained only with PAS and did not contain calcium was noted. Consequently, no definite evidence was found for the occurrence of a polysaccharide-containing lesion prior to calcification. Only cloudy swelling of the tubules was noted in the kidneys of rats injected with turpentine. Since the injection of turpentine resulted in elevated seromucoid and other serum glycoprotein levels, it is concluded that such elevations do not result per se in kidney damage.
Peripheral Resistance Changes and Blood Pooling After Endotoxin in Eviscerated Dogs
Authors: Hinshaw Lerner B. , Gilbert Robert P. , Kuida Hiroshi , Visscher Maurice B.
Published: December 2017

Studies were performed on eviscerated dogs maintained with a constant cardiac inflow with and without injections of lethal amounts of E. coli endotoxin. Continuous recordings of mean arterial blood pressure and total venous return permitted determination of changes in total peripheral resistance and extent of vascular pooling. A significant fall in mean arterial blood pressure occurs within 30 minutes after endotoxin in the eviscerated dog with constant cardiac inflow. There is therefore a decrease in total peripheral resistance. There is also a small but significant increase in vascular pooling exceeding that seen without endotoxin but much reduced from that observed in noneviscerated animals given endotoxin. It is concluded that a decrease in vascular tone occurs after endotoxin and that it probably plays a significant role in the later phase of endotoxin shock in the dog.
Effect of and Interaction Between Tranquilizers, Serotonin and Lysergic Acid Diethylamide on the Body Temperature of Pigeons
Authors: Hoffman Roger A.
Published: December 2017

The temperature responses of the pigeon to serotonin, reserpine, chlorpromazine and LSD-25 were investigated. It was demonstrated that a rapid hypothermia and depre sioa follow the administration of all compounds except chlorpromazine. Serotonin, reserpine and chlorpromazine were shown to have certain prophylactic and therapeutic value on the LSD-25-induced hypothermia. The data indicate that a mutual antagonism exists in the interaction of these compounds. It is suggested that the mechanism of action of these drugs is quite complex, leading to mixed reactions, depending perhaps on what measurement is being considered.
Kinetics of slow changes in membrane potential induced by direct current polarization of single nerve fibers
Authors: Schoepfle Gordon M.
Published: December 2017

A direct current pulse applied to an isolated single fiber of the frog sciatic induces a slow drift in membrane potential which can be described by a single exponential term throughout most of its time course. Both magnitude and time parameter are functions of pre-existent membrane potential. With increasing cathodal polarization the magnitude of the drift approaches a limiting value which is dependent only on the duration of the polarizing pulse. No change in resistance is detectable with brief test transient pulses. In fibers sufficiently hyperpolarized to minimize sodium inactivation it is observed that impulses fired off at any time during the course of the slow potential drift are characterized by identical peak values of membrane potential. This indicates that active firing results in a short circuiting of the mechanism responsible for the slow drift. Whereas the data presented favor a change in some e.m.f. as responsible for the slow drift, there exists strong evidence that the potassium emf remains constant.
Correlation between brain cholinesterase and brain weight within two strains of rats
Authors: Krech David , Rosenzweig Mark R. , Bennett Edward L.
Published: December 2017

Brain weight and cholinesterase (ChE) activity of cortex and of subcortical brain were measured in 176 male rats of two strains. The correlation between subcortical ChE activity and brain weight is –.66 for one strain, and –.27 for the other strain. Both correlations, and the difference between them, are significant. For cortical ChE activity and brain weight, no significant relationship was found. Thus, previous conclusions that cortical ChE activity decreases from species to species as brain weights increase find a parallel for subcortical ChE within a single species and even within a single strain. The failure of cortical ChE to correlate with brain weight supports the suggestion of a functional difference between cortical and subcortical ChE activity.
Factors in the pattern, timing and predictability of hibernation in the squirrel, Citellus beecheyi
Authors: Strumwasser Felix
Published: December 2017

Ground squirrels, Citellus beecheyi, bearing permanently implanted brain thermocouples never entered deep hibernation in one simple temperature decline. The pattern consisted of entering into and arousing from hibernation several times, each succeeding hibernation terminating at a lower brain temperature until a final plateau was reached. The entrances before the final plateau are considered test drops and evidence is presented that each of the low brain temperatures reached is a critical point. This pattern of hibernation was independent of season. The critical brain temperature/time curve is suggestive of the integrated rate of metabolic preparations necessary for entering hibernation. From the thermoregulatory behavior of the critical points, it appears that the temperature regulating mechanism is being informed of the state of biochemical preparations for hypothermia and controls the depth of each temperature drop accordingly. Arousals from hibernation, particularly during the test drop period, occur at preferred times, at statistically significant 1-hour intervals, but the time of entrance and the first plateau are randomly distributed within two selected portions of the day. Evidence is presented that this species' time sense is due to a temperature-independent internal clock. A ‘three-factor theory’ explaining the triggering of hibernation is proposed and developed.
Role of afferent activity from the bladder in regulating its activity
Authors: Marsh Donald J. , Suzuki George , Meyers Frederick H.
Published: December 2017

Sympathetic efferent activity to the bladder was recorded from the hypogastric nerves of cats. When the pelvic (afferent) nerves were sectioned or a local anesthetic applied, sympathetic activity decreased. It is concluded from these data and from previous work that sympathetic inhibitory tone necessary for normal function is maintained by afferent activity from the bladder. Nerve section experiments are reinterpreted in the light of these data.
Active transport of Ca45 by the small intestine and its dependence on vitamin D
Authors: Schachter David , Rosen Samuel M.
Published: December 2017

Everted gut-sacs prepared from segments of the proximal small intestine of young rabbits, rats and guinea pigs transport Ca45 in vitro from the mucosal to the serosal surfaces against concentration gradients. The active transport mechanism is limited in capacity, is dependent on oxidative phosphorylation, and appears to be relatively specific for Ca++ and Mg++ in contrast to Sr++ and Ba++. Vitamin D deprivation in rabbits and rats markedly impairs the capacity for active Ca45 transport in vitro. The vitamin thus has an effect directly on the upper small intestine. Neither the active Ca45 transport nor the effect of vitamin D on the transport can be explained by an accumulation of citrate and the formation of the calcium-citrate complex.
Effects of khellin on coronary blood flow and related metabolic functions
Authors: Farrand Richard L. , Horvath Steven M.
Published: December 2017

Khellin, a drug employed as a coronary dilator, was tested to determine its effects on the cardiovascular system of the dog. Ten mongrel dogs were anesthetized with Nembutal and, after control observations were made, given an intravenous administration of 1 mg/kg body weight of khellin. Coronary blood flow and cardiac output samples were drawn during the control period and at 10, 40 and 80 minutes after administration of the drug Cardiac output was calculated by the direct Fick principle and coronary blood flow by the nitrous oxide method. There was a significant (5%) increase in the arterial oxygen content during the 10- and 40-minute intervals, but no change was observed at 80 minutes. An increase in arterial-mixed venous oxygen difference occurred at 40 and 80 minutes. No change in systemic arterial pressure or cardiac output was noted at any time. Coronary blood flow had decreased slightly at 80 minutes. A significant decrease in carbon dioxide content of the arterial, pulmonary arterial and coronary sinus blood was observed, possibly as a consequence of hyperventilation. Khellin appeared to alter the metabolism of the myocardial and splanchnic tissues.
Electrophysiological evidence for specialized fiber types in rabbit atrium
Authors: de Carvalho Antonio Paes , de Mello Walmor Carlos , Hoffman Brian F.
Published: December 2017

Intracellular microelectrodes have been used to study the site of origin and direction of spread of activity in the rabbit atrium. In this study a number of fiber groups have been found which possess specialized electrophysiological characteristics and a consistent anatomical localization. A pacemaker potentiality has been found only in tissues derived from embryologically distinct structures such as the sinus venosus, the venosus valves and the lower segment of the auricular canal. Activity normally spreads slowly from the S-A node and excites the crista terminalis along a broad front. Spread is then rapid through the crista, the pectinate muscles and the fibers of the atrial roof. The septum is normally excited from the crista terminalis. Excitation reaches the A-V node almost simultaneously from the crista terminalis and the right segment of the S-A ring bundle. This latter shows many characteristics of specialized conducting tissue. Around the A-V ring conduction velocity slows markedly in fibers which have many of the electrophysiological characteristics of A-V nodal fibers.
Adrenal cortical function following stepwise removal of the brain in the dog
Authors: Story J. L. , Melby J. C. , Egdahl R. H. , French L. A.
Published: December 2017

Previous studies indicate that hypothalamic lesions will prevent adrenal cortical response to stress. The present study was undertaken to determine if higher centers of the brain are necessary for adrenal cortical hypersecretion of 17-hydroxycorticosteroids due to operative trauma. Intermittent samples of adrenal venous blood were obtained from dogs by means of adrenal cannulas and 17-hydroxycorticosteroid output was determined. Stepwise removal of the brain was performed, with collections of adrenal venous blood at various levels of anatomic integrity. Removal of the brain down to the hypothalamus resulted in no diminution in the maximal adrenal cortical response following operative trauma as measured by 17-OH-corticosteroid output. After removal of the hypothalamus there is a persistence of adrenal corticoid secretion up to 6 hours after removal of this structure leaving the pituitary gland intact. It is concluded that a) the CNS above the hypothalamus is not essential for adrenal 17-OH-corticosteroid production in response to operative trauma; and b) adrenal cortical secretion persists in response to stress up to 6 hours after removal of the hypothalamus.
Secretion of calcium by rat submandibular gland
Authors: Dreisbach Robert H.
Published: December 2017

The mean concentration of calcium in rat submandibular gland saliva after maximal pilocarpine stimulation was initially 3.2 µEq/gm and gradually fell during the 1st hour to 0.93 µEq/gm. The final concentration was approximately 30% of the concentration of calcium in the serum ultrafiltrate whether the total serum calcium was normal or elevated threefold by the infusion of calcium chloride. At the end of the transient phase, the gland calcium concentration was from 28 to 57% less than the initial gland concentration depending upon the type of anesthesia used. The calcium loss from the gland correlated well with the excess calcium secreted in the saliva during the transient phase. After the initial transient phase was ended, the saliva calcium concentration bore an inverse relationship to the secretory rate and was directly proportional to the serum ultrafiltrate calcium concentration.
Cardiovascular and respiratory reflexes from the left side of the heart
Authors: Aviado Domingo M. , Schmidt Carl F.
Published: December 2017

In anesthetized dogs increasing inflow into the left side of the heart (vascularly isolated from the lungs) causes bradycardia. This response is not mediated by the aortic depressor nerve but is dependent on an intact vagus. Obstruction of flow by inflating a balloon in the aortic valve causes bradycardia, vasodilatation of the perfused hind legs and respiratory inhibition which are dependent on an intact vagus. The participating pressoreceptors are believed to be in the walls of the left ventricle rather than the left atrium.
Changes in the dimensions of the venae cavae
Authors: Irisawa Hiroshi , Greer Alexander P. , Rushmer Robert F.
Published: December 2017

In 11 dogs a variable resistance gauge, a bonded strain gauge, or mutual inductance coils were installed on the venae cavae under aseptic surgical conditions so that dimensional changes in unexposed veins could be measured directly. The cyclic patterns of dimensional change resembled inverted images of venous flow records obtained by others. Since some changes in the venous dimensions apparently were not related to pressure, active contraction of the walls may have been responsible. Studies involving infusion and hemorrhage confirmed the existence of two phases in the pressure-diameter relationship correlated with the level of venous pressure. The pattern of diameter and venous pressure changes during transfusion and withdrawal of blood tended to be a clockwise hysteresis loop.