bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Growth Hormone Preparations on Cardiac Hypertrophy and Blood Pressure of Hypophysectomized Rats
Authors: Beznák Margaret
Published: December 2017

Of three growth hormone preparations only one (PGH 163-208A, Armour) restored cardiac hypertrophy and hypertension on aortic constriction in hypophysectomized rats near to the level seen in normal rats. The same aortic constriction caused no increase in the weight of the heart and no hypertension in untreated hypophysectomized rats and in similar rats treated with a bovine growth hormone preparation (R 285-174, Armour) or crystalline growth hormone (Dr. Li, Berkeley). The different action of the three preparations was not connected with their effect on appetite and on body growth. ACTH, 5 mg/rat/day, caused adrenal hypertrophy in hypophysectomized rats without raising their blood pressure. The weight of the heart and particularly the blood pressure after aortic constriction were, however, greater in hypophysectomized rats treated with ACTH than in their nontreated controls.
Detection of Coronary Atherosclerosis in the Living Rabbit by the Ergonovine Stress Test
Authors: Rinzler Seymour H. , Travell Janet , Karp Dorothy , Charleson Diana
Published: December 2017

Electrocardiograms were taken before and during 15 minutes after administration of 0.05 mg/kg and, on occasion 1 mg/kg, of ergonovine maleate intravenously for a total of 94 ergonovine stress tests on 34 rabbits. Fourteen animals were controls and twenty, cholesterol fed. One series was kept on the diets for about 2.5 months and another for about 5 months. Positivity of the ergonovine stress test was indicated by a drug-induced depression of the S-T segment amounting to 0.5 mm or more below the isoelectric level in either leads II or IV. Hearts were examined microscopically, aortas grossly. In control animals, ergonovine stress tests were uniformly negative and coronary arteries and myocardium normal. In cholesterol-fed rabbits, after 2.5 months the ergonovine stress test was likewise negative but there was atherosclerosis of the thoracic aorta, diffuse fatty infiltration of the myocardium and marked cholesterolemia. After 5 months, the ergonovine stress test had become positive in all cholesterol-fed rabbits. At this time, each animal showed subendothelial lipid accumulation in the coronary arteries with occlusive intimal atherosclerosis, and in the myocardium, fatty infiltration and spotty hyaline degeneration. Data show a correlation of positivity of the ergonovine stress test with occlusive atherosclerosis of the small coronary arteries and myocardial damage. It is suggested that this test may provide an experimental procedure for the study of coronary atherosclerosis in the living animal.
Regulation of the Circulation During Exercise
Authors: Barger A. C. , Richards V. , Metcalfe J. , Günther B.
Published: December 2017

Oxygen consumption and cardiac output (direct Fick) have been measured in normal dogs at rest and during graded exercise on the treadmill up to a work intensity of 5 mph and 10°. Systemic and pulmonary artery pressures have also been recorded. The changes in cardiac output produced ‘at rest’ by excitement were frequently as large as those induced by moderate exercise. A short bout of exercise followed by a rest period was far more efficacious in producing lower and more uniform results during rest and subsequent exercise than a prolonged rest period alone. Under such conditions the ‘steady state’ was reached in 3 minutes or less of exercise. The linear relation between oxygen consumption and cardiac output during exercise in the dog is similar to that observed in man, and in the horse. The possible significance of this similarity is discussed and it is suggested that the data are consistent with the hypothesis that the increase in blood flow during exercise is largely the increase in muscle flow with a constant arteriovenous oxygen difference of approximately 14 vol. %.
Relative Rates of Passage of H1H3O16 and of H12O18 Across Pulmonary Capillary Vessels in the Dog
Authors: Enns Theodore , Chinard Francis P.
Published: December 2017

Relative rates of passage of H1H3O16 and H12O18 across the pulmonary capillaries of the dog have been examined. No significant difference has been found. In previous studies ( Am. J. Physiol. 178: 203, 1954), no significant difference was found in the relative rates of passage of H1H2O16 and H1H3O16. It is concluded that H12O18, H1H2O16 and H1H3O16 may be used interchangeably as tracers for each other and as tracers for ordinary water, H12O16, in biological systems in which physico-chemical processes such as diffusion are involved.
Inulin Space as a Function of Equilibration Time
Authors: White H. L. , Rolf Doris
Published: December 2017

Recovery of alkali-stable inulin injected intravenously into nephrectomized rats is complete at 30 minutes and at 3 hours, but falls progressively to 73% at 72 hours. Whole body inulin space is less than Cl space at 30 minutes and 3 hours, equals Cl space somewhere between 15 and 24 hours, and exceeds total body water at 72 hours. Inulin in cells is still in alkali-stable form. Alkali-stable inulin space equals total inulin space. Inulin space at 72 hours greatly exceeds water content in three tissues, liver, skin and spleen, rich in macrophages, while it is less than water content in a tissue, skeletal muscle, poor in macrophages. It is postulated that macrophages actively ingest and concentrate inulin. Rise in inulin space follows a straight semilog line rather closely, but this cannot be taken as proof that a single exponential process is operating. Since inulin space never levels off, the period of equilibration for the best measurement of ECF is uncertain.
Modification of Acute Intestinal Radiation Syndrome Through Shielding
Authors: Swift Marguerite N. , Taketa S. Tom
Published: December 2017

Mortality associated with intestinal injury in rats occurring 3–5 days after 1000 r x-irradiation was significantly decreased by shielding, during exposure, a small exteriorized section of duodenum or ileum. Protection was not obtained by shielding either the distal half of the cecum or the whole stomach. Beginning recovery of radiation-induced small intestine weight loss was observed 4 days after 1000 r in rats irradiated with a section of ileum shielded, whereas no recovery had occurred by this time in nonshielded controls. This effect was not demonstrable at 875 r, a dose that produced no acute intestinal deaths in either control or experimental group. An intermediate dose of 500 r to the ileal section under exposure conditions otherwise identical to the 1000-r experiment decreased the incidence of early deaths but failed to affect intestinal weight significantly as compared with controls without ileal shielding.
X-Irradiation and Lipoprotein Metabolism in Various Species
Authors: Hewitt John E. , Hayes Thomas L.
Published: December 2017

The changes in lipoprotein concentration following x-irradiation have been presented for the rabbit, dog, rat and mouse. The most striking lipoprotein changes in the four species were: a) a large increase in the concentration of the low density lipoproteins of the rabbit at 30 hours postirradiation; b) increased concentrations of the two lower density classes and decreased concentrations in the highest density class in the dog at 10–13 days postirradiation; c) elevated concentrations of the high density lipoproteins at 3 days and the low density lipoproteins at 8 days in the rat; d) a pronounced decrease in the concentrations of the high density lipoproteins of the mouse at 4 days. Hyperlipoproteinemia is associated with higher average flotation rates for the lipoprotein molecules, indicating qualitative as well as quantitative changes in the metabolism of lipids in the irradiated animal. A relatively large increase in the concentration of the low density lipoproteins precedes death from irradiation in the rabbit, rat and dog.
Cholesterol Vehicle in Experimental Atherosclerosis
Authors: Kritchevsky David , Moyer A. W. , Tesar W. C. , McCandless R. F. J. , Logan John B. , Brown Raymond A. , Englert Mary E.
Published: December 2017

The severity of atheromata in cholesterol-fed rabbits appears to vary inversely with the iodine number of the fat used as vehicle for the sterol. The serum cholesterol levels increase with increasing iodine number and the serum lipoprotein levels vary, depending on the class of lipoproteins being studied.
Effect of Acute Hyponatremia on Distribution of Water and Electrolytes in Various Tissues of the Rat
Authors: Woodbury Dixon M.
Published: December 2017

Effects of acute hyponatremia, induced by intraperitoneal injection of isosomolar glucose solution, on electrolyte distribution in various tissues of rats have been studied and the following results were obtained. The hyponatremic procedure increases intracellular brain Na concentration, decreases K concentration and results in a slight but insignificant decrease in brain water. Muscle Na, K and Cl concentrations are decreased and Na space is smaller than Cl space; cellular hydration occurs. In the heart, Na and Cl spaces decrease, and there is no change in K concentration; cellular hydration also occurs. Bone responds with a marked loss of cellular Na and a slight decrease in Cl space; K concentration is unchanged; cellular hydration results from the procedure. Skin responds in still a different manner; Na and Cl spaces and K concentration are unchanged; however, dehydration rather than hydration occurs in skin. The implications of the various changes in tissue water and electrolytes associated with the acute hyponatremia are discussed and various tissues are postulated to be storage sites for Na and/or water. It is concluded that each tissue has its own intrinsic control of electrolyte and water metabolism.
Effects of Denervation on the Histochemical Characterization of Skeletal Muscle During Growth
Authors: Eichelberger Lillian , Akeson Wayne H. , Roma Michael
Published: December 2017

Skeletal muscle, which has been histochemically characterized by: a) extracellular tissue comprising extracellular fluid plus connective tissue solids, and b) intracellular tissue comprising intracellular water and fiber solids, has provided a method to interpret quantitatively what occurs when skeletal muscle atrophies. Histochemical findings from skeletal muscle (calf and thigh groups) from the legs of puppies following disuse brought about by denervation were compared with those obtained on muscles removed from the opposite weight-bearing leg, the control leg. All tissue data were calculated on a fat-free basis. The calculation of the extracellular tissue mass was based on the chloride space, and the estimation of the connective tissue solids was based on the collagen nitrogen values. The histochemical interpretations indicated that following the denervation of muscle the change of greatest magnitude was in the mass of the extracellular tissue. In a kilogram of control calf muscle the extracellular mass (F) was 295 gm, of which 47 gm were the connective tissue solids. In a kilogram of denervated calf muscle the (F) was 397 gm, of which 57 gm were connective tissue solids. In a kilogram of control thigh muscles the (F) was 249 gm containing 41 gm of connective tissue solids; and there were 378 gm in the (F) of the denervated thigh containing 52 gm of connective tissue solids. After correcting the determined total solids of the muscles for the connective tissue solids, the remaining solids were allotted to the muscle fiber solids. Therefore in atrophied muscle there was a decrease in the muscle fiber solids of 166 gm (control) to 137 gm (denervated). Since histologically a definite shortening of fibers has been found, the histochemical decrease in the fiber weight must be the result of shortening of the muscle fibers. Histochemical evidence that the internal structure of the muscle fibers did not change in denervation was provided by the findings that the calculated concentrations of potassium (156 mEq) and magnesium (30 mEq)/kg of muscle fiber water did not differ from the control values. Likewise, the amount of water per kilogram of muscle fibers remained the same: 77% in the control and denervated calf muscles, and 78% in all of the thigh muscles.
Immunochemical Relationship of Human Plasma Beta-Lipoprotein and Chylomicrons
Authors: Middleton Elliott
Published: December 2017

Sf 3–8 human plasma beta-lipoprotein was prepared in the ultracentrifuge and was shown to be electrophoretically and ultracentrifugally homogeneous. Studies of this material with rabbit antisera to it indicated marked immunological inhomogeneity by agar gel diffusion and supernatant tests. Saline washed human chylomicrons reacted with the anti-beta-lipoprotein sera only after steapsin hydrolysis of the chylomicrons. No reaction between washed hydrolyzed chylomicrons and anti-human-serum-albumin rabbit serum was noted. Serial absorption studies indicated that chylomicrons and Sf 3–8 beta-lipoprotein are not immunologically identical but in the low density chylomicron fraction there is some substance antigenically related to Sf 3–8 beta-lipoprotein.
Role of Red Blood Corpuscles in Regulation of Renal Blood Flow and Glomerular Filtration Rate
Authors: Kinter W. B. , Pappenheimer J. R.
Published: December 2017

Renal blood flow was measured as a function of arterial red cell concentration in acute experiments on anesthetized cats breathing oxygen. Renal blood flow changed only slightly when the arterial red cell concentration was varied over the range 20–55%, despite large changes in the viscosity of blood as measured in a glass tube or in a perfused hindleg. When the red cell concentration was progressively reduced below 20%, however, the blood flow (measured at constant pressure) increased greatly, despite the fact that blood viscosity changes very little in this range of cell concentrations. Renal blood flow and glomerular filtration rate (creatinine clearance) were measured as a function of arterial pressure at normal and at very low arterial red cell concentrations. Autoregulation of both renal blood flow and filtration rate was partly or wholly abolished at low red cell concentrations. Autoregulation returned when cells were restored. The experimental results are explicable in terms of the cell-separation theory of renal hemodynamics (1). According to this theory the renal blood flow and glomerular filtration rate are largely controlled by the efficiency of separation of red cells from plasma in the interlobular arteries. Many observations which were previously attributed to differential changes in afferent and efferent arteriolar resistance can be equally well accounted for in terms of the cell-separation theory.
Acute Effects of Denervation on Kidney Function in the Dog
Authors: Sartorius O. W. , Burlington H.
Published: December 2017

Alterations in renal function produced by acute renal denervation were studied in anesthetized and unanesthetized female dogs and in crossed perfusion preparations. Initially, the renal nerves of both kidneys were isolated under anesthesia, and silk thread placed loosely around the nerve bundles and brought to the outside through a flank incision. Ureteral catheters were inserted and tied in place. Urine was collected on succeeding days and after a suitable control period one kidney was acutely denervated by a single pull on the thread, following which urine samples were collected. In the crossed perfusion preparation the left kidney received its entire blood supply from the carotids of a donor dog. The nerves were intact during control periods. Glomerular filtration rate, renal plasma flow, water excretion and sodium and potassium excretory rates were studied before and after denervation. Renal arterial pressure was rigidly controlled and experimentally altered throughout. Results indicate that acute denervation produces a significant and immediate increase in urinary sodium concentration and excretion and that this increase is independent of any alteration in renal hemodynamics. A direct influence of the renal nerves on reabsorbtive activity of renal tubules is suggested.
Cardiovascular Effects of Acutely Raised Intracranial Pressure
Authors: Brown Faith K.
Published: December 2017

Cardiovascular effects of acute elevations of intracranial pressure were studied, with special reference to three questions: a) whether vasoconstriction or cardiac stimulation is primarily responsible for the pressor response to this stimulus; b) whether the ultimate nature of the stimulus is neurogenic or humoral; and c) whether or not changes in venous tone occur in response to ICP elevation. It is concluded from the experimental findings that vasoconstriction was the dominant factor in the response, that the reflex is primarily neurogenic, and that the venomotor system shows an active constriction which accompanies the arterial pressure rise.
Urinary Composition During Hypothermia
Authors: Segar William E. , Riley Philip A. , Barila Timothy G.
Published: December 2017

Five dogs were cooled artificially to 22°C and then warmed to 37°C. Blood and urine chemical changes were periodically studied. An increase in whole blood ph and a decrease in serum potassium were observed; and little change in hematocrit, serum Na, Cl or total CO2 concentrations occurred during cooling. Both blood ph and serum potassium concentrations returned to normal values upon warming the animals. Urine flow increased with cooling and the U/P ratios of sodium, potassium and chloride approached unity as body temperature was progressively lowered. The U/P ratio of creatinine dropped from 150 to 8. The ability of the kidney to produce ammonia or to acidify the urine decreased in a linear manner as cooling progressed and returned promptly upon warming. The changes in volume and composition of the urine which were produced by cooling, indicate that such urine is essentially glomerular filtrate which has undergone isosmotic reabsorption but which has remained unaltered by further renal tubular activity.
Cardiac Output by the Dye Dilution Technique Under Thiopental Sodium-Oxygen and Ether Anesthesia
Authors: Greisheimer Esther M. , Ellis Dorothy W. , Stewart George , Makarenko Lydia , Oleksyshyn Nadia , Thompson Kenneth T.
Published: December 2017

One hundred-twenty determinations of cardiac output by the dye dilution technic utilizing the cuvette oximeter were made on 20 dogs. Of these, 60 were done under thiopental sodium-oxygen analgesia and 60 were done after supplementing with ether. Arterial blood pressure was recorded by strain gauge. Electrocardiograms were taken periodically. Concentrations of thiopental and ether in arterial blood were determined. Cardiac output began to increase under thiopental analgesia and continued to increase when ether was administered. Arterial blood pressure and heart rate decreased slightly when ether was administered. Stroke index increased when ether was administered. Total peripheral resistance decreased markedly under thiopental analgesia, and continued to decrease when ether was administered. When compared with an earlier study in which cyclopropane was used as the supplementing agent, it was found that cyclopropane and ether exert opposite effects on cardiac output and peripheral resistance despite the fact that the effect on arterial blood pressure is similar under the two agents. Increase in cardiac output was found to be parallel with decrease in total peripheral resistance in this study. Amount of dye injected did not influence cardiac output. Under the conditions of this study, cardiac output was in no way dependent on the concentration of thiopental in the blood nor on the amount injected. Level of ether in the blood did not show much effect, if any, on cardiac output. It is probable that the changes observed in this study are comparable with those which obtain clinically when thiopental-oxygen analgesia is supplemented with ether. Systolic blood pressure is not an infallible guide to other cardiovascular functions since it may remain fairly steady while cardiac output and peripheral resistance undergo marked changes under anesthesia.
Absorption of Serotonin (5-Hydroxytryptamine) by Canine and Human Platelets
Authors: Zucker Marjorie B. , Borrelli Jennie
Published: December 2017

Serotonin absorption was studied by incubating platelets for 5 or 10 minutes at room temperature with synthetic serotonin in a concentration of 0.2–4 µg/ml. Serotonin disappeared from the supernatant in two experiments with canine platelet-rich plasma, seven experiments with human platelet-rich plasma and three out of four experiments with native whole human blood. It did not disappear in four out of nine experiments using washed dog platelets suspended in saline and in none of five experiments with washed human platelets. Assay of the platelets in two experiments with human platelet-rich plasma demonstrated that much or all of the serotonin could be recovered in the platelets. The ability of the platelets to absorb serotonin could be correlated with their morphological appearance. Normal disc-shaped platelets absorbed serotonin, whereas spiny spherical platelets often seen in shed blood did not. The quantity of serotonin absorbed by washed dog platelets or by human platelets in platelet-rich plasma from a solution of 0.2 µg/ml was about 0.38 µg/109 platelets, and virtually all of the serotonin was taken up. When the initial concentration was 2 µg/ml, human platelets absorbed up to 2.8 µg/109 platelets, and appreciable quantities of serotonin were left in the supernatant.
Effect of Intermittent Nitrogen Exposures on Tolerance to Oxygen at High Pressures
Authors: Penrod Kenneth E.
Published: December 2017

If the exposure of guinea pigs to 4 atm. oxygen pressure is interrupted at 30-minute intervals with exposures to air or oxygen-nitrogen mixtures, the total survival time of the guinea pigs is significantly increased. Five-minute exposures to air increase the survival time by 40% with increasing benefits from 10-minute and 20-minute exposures to air. If the oxygen pressure is increased to 5.5 atm. the intermittent air exposures must be 20 minutes in length to significantly increase survival time. In addition to significantly increasing survival time intermittent air exposures have the apparent effect of reducing the frequency of convulsions. An explanation is advanced for the finding of a significant influence on survival at 4 atm. based on the observation that pulmonary damage is the usual cause of mortality at this pressure of oxygen. Since the pulmonary damage has been shown to be in large measure an atelectatic process a theory is proposed that nitrogen inhaled during the intermittent air breathing period is carried by the blood to those areas of the lungs in the process of collapse and the infiltration of nitrogen into the collapsing air sacs has the effect of reinflation, thereby delaying the process. This is not thought to be the sole mechanism responsible for the beneficial effects of intermittent nitrogen breathing on oxygen toxicity as it is not clear how such a mechanism could influence the convulsion frequency.
Transfer of Potassium Between Blood, Cerebrospinal Fluid and Brain Tissue
Authors: Rudolph Guilford G. , Olsen Norman S.
Published: December 2017

Anesthetized dogs were injected with radioactive potassium. After intravenous injection the appearance of the ions in cerebrospinal fluid was a summation of two exponentials with the maximum at about 30 minutes. The ratio of radioactivities of brain tissue to cerebrospinal fluid was stabilized at 120 minutes, whereas the ratio of cerebrospinal fluid to plasma reached this state after 30 minutes. After intracisternal injection the disappearance of K42 from cerebrospinal fluid was described by two exponentials. The activity in the plasma reached a maximum at 10–15 minutes and thereafter paralleled the disappearance curve from cerebrospinal fluid. Brain tissues did not reach equilibrium. These data have been compared with those obtained using radioactive sodium and bromide and discussed in relation to cerebrospinal fluid formation.
Blood Pressure Responses to Epinephrine in the Etherized Dog, Before and After Baroreceptor Denervation
Authors: Hilton James G. , Brown Robert V.
Published: December 2017

Experiments were performed on dogs anesthetized with ether to determine the effects of denervation of the baroreceptors upon the blood pressure responses to graded doses of epinephrine. The results of these experiments show that the denervation procedures do not significantly affect the peak blood pressure attained or the duration of the rise in blood pressure resulting from doses of epinephrine. Denervation of the baroreceptors elevated the level of the control blood pressure and reduced the height of the pressor response significantly. At all but the 10.0 µg/kg dosage level the difference in the pressor response could be accounted for by the difference in the control blood pressure.
Pressor Response to Adrenalin Shown by Spinal Dogs
Authors: Mooring Paul K. , Rathe John , Root Walter S.
Published: December 2017

Intravenous injection of Adrenalin (1 ml of 1:300,000–1:25,000) into 10 normal, anesthetized (Nembutal) dogs produced an average increase in mean arterial pressure which amounted to about 25 at the lower and 100 mm Hg at the higher doses. Essentially the same responses were shown by seven anesthetized, vagotomized dogs and five anesthetized, vagotomized animals in which the carotid regions were denervated. Eight anesthetized dogs with spinal cords cut between C8 and T1 showed after Adrenalin injection an average percentage increase in mean arterial pressure which was some threefold greater than that found in normal, anesthetized animals. This difference was increased still further by bilateral section of the vagi in eight spinal dogs. Section of the spinal cord one or two segments below C8 to T1 (4 dogs) decreased the response to Adrenalin. The increase in mean arterial pressure induced by the intravenous injection of Adrenalin was greater in six spinal dogs (C8 to T1) anesthetized with Nembutal than in two similar unanesthetized animals. Acute changes in plasma volume did not influence the magnitude of the blood pressure response to Adrenalin shown by four high spinal animals.
Age Changes in Body Size, Body Composition and Basal Metabolism
Authors: Conrad M. C. , Miller A. T.
Published: December 2017

The interrelations of body size, body composition and basal metabolism were studied in 69 albino rats ranging in age from 18–174 days. The decline in metabolic rate with age was more rapid than would be predicted from the weight0.75 rule which eliminates the influence of body size in interspecific measurements. Body composition analyses indicated that the increase with age in metabolically inert fat and bone minerals was approximately balanced by a corresponding decrease in metabolically inert extracellular fluid, so that ‘active tissue mass’ was virtually unchanged. Calculations based on data in the literature indicate that about one-half the decline in metabolic rate with age may be due to the corresponding decrease in the relative weight of the viscera. The remainder of the decline in metabolic rate must be due to factors other than changes in the chemical or histological composition of the body.
Effect of Fibrinolytic Activation on Survival and Cerebral Damage Following Periods of Circulatory Arrest
Authors: Crowell Jack W. , Smith Edward E.
Published: December 2017

Experiments presented show that dogs given Varidase, a fibrinolytic activator, can withstand circulatory arrest for longer periods of time than control animals. Fifteen control animals were subjected to 10 or 15 minutes of circulatory arrest and only one survived. Fourteen animals were given Varidase plus human plasma and twelve survived. Additional evidence indicating a coagulation defect during circulatory arrest is presented.
Physiologic Properties of Anserine and Carnosine
Authors: Sutfin D. C. , Hines H. M.
Published: December 2017

Studies were made of physiologic responses to anserine and carnosine, isolated and synthetic, as measured by changes in diastolic, pulse and systolic blood pressure and peripheral blood flow in the cat and dog, and by oxytocic effects on smooth muscle of guinea pig and rabbit. Both dl-anserine and l-carnosine exhibited a feeble depressor action on blood pressure and a weak oxytocic activity. The wide variations in the activity of these peptides from various natural and synthetic sources is attributed to contamination with traces of other physiologically-active substances with a histamine-like action. The activity is dependent upon peptide linkage and not exhibited by the free amino acid components.
Role of Renal Tubular Secretion in Potassium Homeostasis
Authors: Koch Alan R. , Brazeau Paul , Gilman Alfred
Published: December 2017

The changes in Na and K excretion which accompanied induced changes in Cl excretion were studied in K-depleted and K-fed dogs. Diuretic agents and infusions of isotonic sodium chloride solution were used to vary Cl excretion both when the animals were normally hydrated and during water diuresis. In all cases, it was found that changes in Na excretion were accompanied by quite regular and predictable changes in K excretion. In K-depleted dogs, the ratio of the increment in Na excretion to that of K excretion approximated the ratio of the two ions in the glomerular filtrate. This relationship suggests that the renal tubule, in reabsorbing Na and K in conjunction with anions, makes no distinction between the two cations. Thus the renal control of potassium homeostasis depends largely on the tubular secretion of the ion. In dogs in which the stimulus for distal tubular secretion of K had been maintained by a K-rich diet, the increments in K excretion as Na excretion was increased were observed to be much larger than in the K-depleted dogs. It is concluded that this finding demonstrates a partial dependence of distal K secretion upon the availability of the lumenal component of the Na-K exchange mechanism.
Rate of Elimination of Labeled Carbon Dioxide From the Body
Authors: Drury Douglas R. , Wick Arne N. , Almen Mary Carol
Published: December 2017

When C14-labeled bicarbonate is injected intravenously about 10% of it is exhaled within 30 seconds by the lungs before it is mixed with body CO2. Labeled CO2 that has escaped elimination by the lungs is mixed with body CO2 in a complex manner. The CO2 in those tissues with a high blood flow equilibrates very rapidly with that of the blood. Resting muscle and skin need at least 5 minutes for equilibration with the CO2 of the blood. Calculations of body CO2 pool based on the assumption of complete instantaneous equilibrium between blood and tissues are not valid. The manner of elimination of labeled CO2 produced in metabolism is complex and does not simulate that following intravenous or intraperitoneal injection of labeled bicarbonate.
Influence of Epinephrine and Norepinephrine on Respiratory Variations in Vascular Pressures
Authors: MacCanon D. M. , Horvath Steven M.
Published: December 2017

Comparisons were made between the respiratory variations in right and left ventricular and femoral arterial pressures of anesthetized dogs before and after the administration of l-epinephrine and l-norepinephrine. These analyses revealed significant deviations from control patterns following administration of these pressor drugs, but only at isolated points in the respiratory cycle. Many of these alterations could only be explained on the basis of alterations in cardiac and/or vasomotor activity.
Post-Tetanic Potentiation in the Visual System of Cats
Authors: Hughes John R. , Evarts Edward V. , Marshall Wade H.
Published: December 2017

Post-tetanic potentiation (PTP) has been demonstrated in the soma response of the geniculate and in the positive potentials of the cortex by stimulation of the cat's optic nerve and recording from the lateral geniculate and visual cortex. Within limits, an increase in duration and intensity of tetanus produces an increased amount of PTP which lasts for a longer time. Occasionally the tract response is potentiated. Various explanations are offered to account for this change and the results are discussed in relation to the probable site of action of PTP. In any case the type of PTP examined in these experiments using anesthetized animals appears to be a property of the subnormal phase with a concomitant increase in the subliminal fringe.
Effect of Intra-Arterial Injections of Adrenaline on Spinal Extensor and Flexor Reflexes
Authors: Wilson Victor J.
Published: December 2017

Doses of 5–40 µg/kg of adrenaline, injected into the left renal artery, increase monosynaptic extensor reflexes evoked by single shocks in acute and chronic spinal cats and sustained extensor reflexes in the latter. This effect reaches a peak 1/2–1 minute after the start of injection and lasts several minutes. Low doses evoke only an increase but higher doses may cause more complicated effects: a) a brief early depression sometimes appears; b) following reflex enhancement a late, sometimes irreversible, depression may occur, evidently due to massive action of large doses of adrenaline. Monosynaptic and polysynaptic flexor reflexes are diversely affected by adrenaline. No evidence for a consistent reciprocal action of adrenaline on extensor and flexor reflexes has been obtained. It is suggested that the drug action on cells of the central nervous system may be fairly general, involving modification of some factor determining cellular excitability.
Effect of Intravenous Iron in Experimental Traumatic Shock
Authors: Smith Donn L. , Kibbey Irvin I. , Bierwagen Max E. , Cruse J. R.
Published: December 2017

Intravenous administration of colloidal saccharated iron oxide prior to intestinal traumatization in the albino rat resulted in a significant reduction of the mean survival time. Sodium gold thiosulfate and colloidal manganese hydroxide employed in the same manner did not significantly alter mean survival times. ACTH and cortisone did not modify the deleterious effects of iron in experimental traumatic shock. A decrease in soluble liver iron was observed when traumatization followed the injection of iron. It was concluded that the reduction of mean survival time in iron injected, traumatized animals was due to a specific action of iron and is not the result of generalized heavy metal toxicity.
Phosphorus Metabolism of the Adrenal Gland of the Rat
Authors: Nicholls Doris , Rossiter R. J.
Published: December 2017

Observations were made on the incorporation of inorganic phosphate labeled with P32 into the inorganic P, 20-minute hydrolyzable P and total acid-soluble P of the adrenal gland of rats either maintained at room temperature (22 ± 1°C) or conditioned to cold (3 ± 1°C). In confirmation of previous findings, there was an increase in the incorporation of inorganic P32 into the acid-soluble P of the adrenal of the rats maintained in the cold. Exposure to more severe cold (–5°C) for 2 hours, caused a great increase in the incorporation of inorganic P32 into the acid-soluble P of the adrenal of the nonacclimatized rats, compared to a slight, and statistically insignificant, increase in the acclimatized animals. The adrenal response to cold in the nonacclimatized rats was greatly decreased by the prior administration of cortisone.
Effect of Indigestible Residue (Cellulose) on Elimination of Endogenous and Dietary Cholesterol
Authors: Lin Tsung-Min , Karvinen Esko , Ivy A. C.
Published: December 2017

Effect of increasing the level of alpha cellulose flour in the diet from a 5% to a 20 or 25% level by dry weight on the elimination of endogenous and dietary cholesterol was studied in 6 dogs and 10 rats. The dogs were fed their meal by stomach tube once a day; the rats ate their isocaloric rations voluntarily and completely. It was found that in the dog, elimination of endogenous as well as total (endogenous + dietary) cholesterol was significantly increased by the high level of cellulose, but the calculated absorption of dietary cholesterol was not reduced significantly. In the rats, the increase in cellulose content did not alter the elimination of either endogenous or dietary cholesterol. The high level of cellulose was slightly laxative in the dogs, but not in the rats. When laxation occurs, the possibility that the absorption of endogenous as well as of dietary cholesterol will be decreased should be considered.
Diuresis in Response to Hypoxia and Epinephrine in Infant Rats
Authors: Hoy P. A. , Adolph E. F.
Published: December 2017

Urine flow was measured in newborn and adult rats, urine being collected by means of a small plastic tube surgically inserted into the urinary bladder through the ventral body wall. Epinephrine in subcutaneous doses of 0.3 or 0.6 mg/kg of body weight produced a prompt diuresis which was nearly identical at all ages (1/4, 2, 6 days after birth; and adult). Arterial blood pressure was low in infant rats and was not increased by this dose of epinephrine. When infant rats breathed air low in oxygen (pO2 = 38 mm Hg), prompt oliguria lasted one-half hour; primary diuresis followed; secondary diuresis suddenly developed whenever ordinary air was again supplied. Within 15 days after birth the oliguria and the secondary diuresis were lost; primary diuresis appeared earlier and lasted a shorter time. Whereas rats up to 39 days after birth did not respond to pO2 of 56 mm Hg, adults responded to it with primary diuresis only. The urine produced during infant diureses was dilute as measured by chloride and refractive index, and remained acid. Pitressin did not interfere with these diureses. Adrenalectomy did not prevent the secondary diuresis. Though responses to epinephrine and hypoxia materialized at birth, their amount and character shifted with age, representing the terminal stages in fixiaton of a regulation.
Factors Affecting the Intracellular Distribution of Potassium in Liver, Kidney and Brain
Authors: Auditore G. V. , Holland W. C.
Published: December 2017

Effects of several experimental procedures, known to influence tissue electrolyte metabolism, on the prevailing intracellular distribution of K were studied by the method of homogenization and differential centrifugation. Evidence obtained suggests that specific biochemical mechanisms occurring in the cytoplasm, at the cell membrane, and in the mitochondria are of prime importance in maintaining this normal intracellular distribution. Pharmacological agents known to modify tissue electrolytes metabolism can do so by interfering with reactions occurring in the membrane (diuretics), the mitochondria (2,4-dinitrophenol and epinephrine), or both (the adrenergic mediators and desoxycorticosterone).
Absorption of Acetic Acid and Glycerol From the Rat Stomach
Authors: Herting David C. , Embree Norris D. , Harris Philip L.
Published: December 2017

The absorption of acetic acid from the pylorus-ligated rat stomach in 6 hours showed a typical log-dose response, with 2.0 mm being absorbed at the highest level administered. Under the same conditions, the amount of glycerol absorbed reached and maintained a constant level approximating 0.4 mm. The gastric contents of rats consuming a diet containing 30% of distilled, saturated, partially acetylated monoglycerides contained an average of 5.6 mg (0.09 mm) of free acetic acid/rat.
Pancreatic Response to Histamine in Dogs With Gastrostomies
Authors: Tankel Henry I. , Hollander Franklin , Lester Louis J.
Published: December 2017

The stimulatory action of histamine on pancreatic secretion has been studied in five dogs with a chronic pancreatic fistula and a gastrostomy for continuous gastric drainage. Histamine appears to be a potent pancreatic secretagogue; in doses of 0.1 mg base/kg body weight it gave a response usually one-third to two-thirds of the volume secreted after secretin, and occasionally even more than this fraction. In general, the bicarbonate concentrations varied in accord with the volumes, so that the evidence based on total output of bicarbonate is likewise in agreement with that based on volume. The effect of atropine on the histamine response has been studied in four of these dogs. This agent inhibits the histamine response invariably, and sometimes the inhibition appears to be complete.
Reticulo-Endothelial System in Relation to Drum Shock
Authors: McKenna J. M. , Zweifach B. W.
Published: December 2017

The administration of colloidal matter, sufficient to blockade the phagocytic activity of the reticulo-endothelial system (RES) in the liver and spleen of rats, has a dramatic effect on the subsequent response to drum trauma. Standardized episodes of trauma in the Noble-Collip drum become more lethal and refractory to therapeutic measures. Resistance to trauma, induced by adaptation to doses of increasing severity, is likewise attenuated by blockade of the RES. The predisposing effects were both dose- and time-dependent. The administration of cortisone in large doses (10–20 mg), an amount shown also to depress RES activity, undermines the capacity of normal rats to withstand traumatic shock, but has no such effect on trauma-resistant animals. It is suggested that the physiological adaptation to trauma may involve an altered relation of the RES to corticosteroids.
Role of Reticulo-Endothelial System in Blood Clearance of Cholesterol
Authors: Neveu T. , Biozzi G. , Benacerraf B. , Stiffel C. , Halpern B. N.
Published: December 2017

The clearance rate of colloidal carbon particles is only slightly impaired in rabbits rendered hypercholesteremic by overfeeding cholesterol. Rabbit serum cholesterol injected into rats is cleared by phagocytosis of the reticulo-endothelial cells whether the cholesterol is in the form of chylomicra (cloudy serum) or not (clear serum from fasting animals). The clearance of the foreign serum cholesterol from the blood follows an exponential function with respect to time as for many other colloids and the rate of clearance is inversely proportional to the quantity injected. Interference is observed between the clearance of cholesterol and other colloids when injected simultaneously. Pretreatment of rats with high doses of heparin increases substantially the speed of clearance of foreign serum cholesterol. The mechanism of the action of the R.E.S. in the metabolism of cholesterol is discussed.
Metabolic Effects of Thyroxine, 3,3',5-Triiodothyronine, 3,3'-Diiodo-5-Bromothyronine and 3,3'-Diiodothyronine Administered Orally to Rats
Authors: Gemmill Chalmers L.
Published: December 2017

By using large amounts of (–) thyroxine, (–) 3,3',5-triiodothyronine, (±) 3,3'-diiodo-5-bromothyronine and (±) 3,3'-diiodothyronine in the drinking water of rats, it was found that thyroxine, triiodothyronine and 3,3'-diiodo-5-bromothyronine elevated the metabolism while 3,3'-diiodothyronine had no effect with this method of administration. It was observed that there was a limiting value to the elevation of the metabolism which was soon reached with thyroxine but not with triiodothyronine. The maximal elevation of metabolism obtained with triiodothyronine was +244 in the thyroidectomized animal and +201 in the normal animal. With thyroxine the maximal metabolism was +141 in the thyroidectomized animal and +26 in the normal animal. One hypothyroid rat showed skin changes which healed after 11 days with triiodothyronine in the drinking water.
Modification of Early Radiation Death in Guinea Pigs
Authors: Andrews H. L. , Brace K. C.
Published: December 2017

A series of depressant and anticonvulsant drugs has been used in an attempt to modify the ‘early’ or ‘central nervous system’ death in guinea pigs. Pentobarbital given in anesthetic doses prior to irradiation dramatically alters the course of injury induced by whole body doses of 6000 r or more. Survival time is sharply increased and all signs of convulsions and hyperexcitability are suppressed. Phenobarbital and paraldehyde show similar actions, but the margin of safe dosage is smaller than with pentobarbital. The action of pentobarbital appears to be a true radiation protection. Other drugs, such as diphenyl hydantoinate suppress convulsive activity and lengthen survival time slightly. This is probably due to a sparing action from the intense muscular activity associated with the convulsions. None of the drugs tested showed an effect when given after irradiation.
Effect of Stress by Crowding Prior to and Following Tuberculous Infection
Authors: Tobach Ethel , Bloch Hubert
Published: December 2017

Although it is known that stressing an already infected animal reduces resistance to the infection, the effect of applying stress prior to infection has not been studied. In the present experiments, it was found that this procedure produced significant differences in resistance to infection. Eighty male and seventy-four female B albino C mice were assigned at random to four experimental groups as follows: 1) individually maintained before and after infection; 2) individually maintained before infection and housed in groups of 20 in cages allowing 3 square inches/animal after infection (‘crowded’ condition); 3) crowded before infection and individually maintained after infection; and 4) crowded before and after infection. These animals were infected with a dose of tubercle bacilli resulting in a chronic disease. It was found that males and females reacted differently to the experimental treatment. Males which were crowded before or after injection showed less resistance than the controls whereas females which were crowded before or after injection survived longer than the controls. Seventy-six male and sixty-six female B albino C mice were assigned to experimental groups as outlined above. These animals were infected with tubercle bacilli resulting in acute disease. The factors of sex differences, crowding before infection and crowding after infection all significantly affected the course of the disease. Males and females reacted to the experimental conditions in the same way. It was found that animals which were crowded before infection and maintained individually after infection resisted tuberculosis better than animals which were individually maintained before infection and crowded after infection.
Some Effects of Prolonged Undernutrition on Carbohydrate Metabolism in Rats
Authors: Halmi N. S. , Spirtos B. N.
Published: December 2017

A) Rats fed 10 gm of ground Rockland diet/day for 4–6 weeks and then fasted for 24 hours showed an enhanced insulin sensitivity as compared with ad libitum-fed rats that were fasted for the same length of time. The fasting blood sugar and liver glycogen concentrations were significantly higher in underfed animals. B) Underfed rats were fasted 24 hours, then fed 5 gm/ 100 gm body weight and tested 8 hours later. These rats exhibited a) no greater insulin sensitivity, b) lower blood sugar levels and c) a smaller rise in liver glycogen concentration than similarly treated ad libitum-fed animals. Intestinal absorption of glucose was not diminished in the undernourished rats. C) Cortisone treatment (0.5 mg/100 gm body wt/day for 5 days) abolished the insulin sensitivity of underfed rats without altering the hepatic glycogen concentration. Somatotrophin (0.5 mg Armour standard equivalent/100 gm body wt/day for 5 days) did not improve their insulin tolerance. After functional evisceration, the blood sugar fall (if expressed as percentage of the initial level) was significantly slower in underfed than in ad libitum-fed rats. However, the decline of the blood sugar level appeared to be more markedly enhanced by insulin in the underfed animals.