bluuebunny/crossref_metadata_2025 huggingface dataset:
Inductograph method for recording muscle activity, especially pyloric sphincter physiology
Authors: Louckes H. S. , Quigley J. P. , Kersey J.
Published: December 2017

The inductograph method for registering in vivo muscle activity under physiological conditions is described. The method is applied to a study of the physiology of the pyloric sphincter region of well-trained, unanesthetized dogs, but is readily applicable for similar studies of the heart, uterus, skeletal muscle, etc. The motor activity of the pyloric sphincter and the pyloric antrum during fasting, feeding and gastric evacuation; the response of these regions to parasympatheticomimetic and sympatheticomimetic stimulation; and the role of the sphincter in gastric evacuation is presented. These studies show that the pyloric sphincter and the pyloric antrum are either quiescent and relaxed or the pyloric sphincter contracts momentarily in a rhythmic manner four to six times a minute in response to each propagated antral peristaltic wave. The inherent rhythm of the pyloric sphincter region is almost impossible to alter, but one or more contraction cycles may be inhibited by excitement, epinephrine, atropine, etc. or the inherent rhythm in a quiescent sphincter may be made manifest by feeding, pilocarpine, etc.
Metabolic characteristics of the isolated perfused rat liver
Authors: Ostashever Alvin S. , Gray Irving , Graff Samuel
Published: December 2017

The use of the isolated perfused rat liver for quantitative biochemical studies of liver metabolism over an experimental period of as long as 4 hours is demonstrated. Respiration rates responded immediately to the addition of substrates and the liver could be restimulated by a second dose of substrate, respiration rates reflecting the nature of the substrate. Net amino nitrogen uptake was consistently exceeded by urea nitrogen production, the latter comparing favorably with in vivo rates. Fructose was rapidly removed from the perfusate by the liver, and the liver efficiently removed lactic acid formed by erythrocyte glycolysis. Ketone body production was continuous and within normal in vivo rates. Bile production declined gradually over a 4-hour period.
Reabsorptive response of renal tubules to elevated sodium and chloride concentrations in plasma
Authors: Bresler E. H.
Published: December 2017

Sustained and relatively constant levels of hypernatremia and hyperchloremia were obtained by infusing dogs with 150 ml of 5% or 10% sodium chloride solutions for 30 minutes and following this with infusions of 0.85% sodium chloride at the rate of 5 ml/min. Inulin clearances and serum and urinary sodium and chloride values were determined during a number of periods when plasma sodium and chloride were at normal or near normal values and compared with similar determinations made after hypertonic saline infusions when plasma sodium and chloride were at high but relatively steady levels. For any given rate of glomerular filtration more sodium chloride was reabsorbed at high plasma salt levels than at normal or near normal levels. Moreover, the rate of reabsorption increases as plasma sodium and chloride increase. The enhanced tubular reabsorptive activity toward sodium chloride at a time when a large surfeit of salt exists appears paradoxical when viewed as a consequence of active transport processes. On the other hand, these results are precisely what would be predicted if passive reabsorption of glomerular filtrate occurred in an area of the tubule freely permeable to salt as well as water.
Conduction in smooth muscles: comparative electrical properties
Authors: Burnstock Geoffrey , Prosser C. L.
Published: December 2017

Electrical and morphological properties were correlated in a variety of mammalian smooth muscles. In the sucrose gap electrode the gut muscles (esophagus muscularis mucosae, intestinal muscles and taenia coli) showed small slow waves (5 mv) and spikes (25–45 mv), while dog retractor penis and rat ureter gave spikes up to 110 mv. Membrane depolarization with K2SO4 was 50–72 mv in both groups of muscle; with KCl it was one-third less. Conduction velocity ranged from 15 cm/sec. for esophagus muscle to 4.1 for intestinal muscles and 1.6 cm/sec. for retractor penis. Resistance of 0.5-mm strips in the sucrose gap was approximately 1 megohm for propagating visceral muscles, 5–12 megohms for nonpropagating blood vessel muscles. Fast conduction is correlated with low resistance and high capacitance (in sucrose), brief spikes, short relative refractory periods, low threshold stimulus duration, long fibers and low interfiber spaces (close packing of cells). Conduction required many parallel fibers; it failed in strips less than about 100 µ diameter and conduction distance varied with excitability. The electrical unit is the individual fiber, but the conducting unit involves many fibers. Conduction appears to depend on relatively low resistance paths of parallel fibers which interact electrically. It also depends on excitability of individual cells which is kept high by stretch and chemical agents.
Experimental control of fractures produced by electroconvulsive shock
Authors: McDonald David G.
Published: December 2017

Incidence of fractures following ECS was found to be significantly reduced by placing animals on a water deprivation schedule, thus reducing body weight significantly. Only animals showing ‘clonic-only’, as opposed to tonic-clonic, convulsions developed fractures. Highest incidence of fractures was found to occur after first ECS, incidence tapering off rapidly thereafter. It was concluded that by reducing body weight through water deprivation, as well as manipulating the strength and duration of the convulsing current, incidence of fractures could be kept at a minimum.
Total body water distribution of creatinine and urea in nephrectomized dogs
Authors: Schloerb Paul R.
Published: December 2017

It was the purpose of this study to measure and to compare the volumes of distribution of creatinine, urea and tritiated water in nephrectomized dogs. After bilateral nephrectomy a solution containing known amounts of these was infused intravenously and at a constant rate in some studies. Frequent arterial blood samples were taken during and following infusion for periods up to 20 hours and were analyzed for water and the infused substances. The respective volumes of distribution and rates of dilution were calculated. Isotopic water and urea were distributed in 95% and creatinine in 61% of their final volumes of distribution at the end of a 30-minute infusion. Final equilibrium occurred in about 90 minutes with water and urea and in about 4 hours with creatinine. Creatinine became distributed in 99 ± 3% of the tritiated water volume and in 101 ± 5% of the urea volume. Urea distributed in 98 ± 4% of the tritiated water volume. It is concluded that administered creatinine is distributed in total body water of nephrectomized dogs with an equilibrium time of about 4 hours and that urea is similarly distributed within 1 1/2 hours.
Corticosteroids and accumulation of C14-labeled amino acids and histamine by isolated rat diaphragm
Authors: Wool Ira G.
Published: December 2017

The rate of penetration and the magnitude of accumulation of several utilized C14-amino acids, of the amino acid analogue, α-aminoisobutyric acid-1-C14, and of C14-histamine was measured in intact and cut isolated rat diaphragm. Adrenalectomy was without effect on the rate of entry of the amino acids or of histamine; cortisone administration (2 mg/day) depressed the accumulation of the utilized amino acids, of α-aminoisobutyric acid and of histamine.
In vivo alteration of the pathways of dopamine metabolism
Authors: Williams C. M. , Babuscio A. A. , Watson R.
Published: December 2017

The 24-hour urine of normal fasting rats injected intraperitoneally with 300 µg of C14-labeled dopamine was found to contain an average of 39% of the administered radioactivity as unconjugated homovanillic acid (HVA), 3.4% as homoprotocatechuic acid (HPA), 6.5% as 3-methoxytyramine, and 6.1% as dopamine; 80% of the 3-methoxytyramine was conjugated as the glucuronide. Pretreatment with a monamine oxidase inhibitor resulted in a 10-fold reduction of HVA and HPA excretion and a 3-fold increase in 3-methoxytyramine excretion without affecting the excretion of dopamine. Pretreatment with a catechol-O-methyl transferase inhibitor reduced 3-methoxytyramine excretion to negligible amounts, increased HPA excretion fivefold without affecting HVA or dopamine excretion significantly. The ratio of labeled 3-methoxytyramine to labeled HVA after the injection of 200 µg of labeled 3-methoxytyramine was 0.81, from which it was calculated that 21% of the HVA excreted after an exogenous load of dopamine was derived from the 3-methoxytyramine pathway and 79% was derived from the HPA pathway. An unidentified metabolite was found in the catecholamine fraction of urine after monamine oxidase inhibition and after pretreatment with ethanol (1.9 and 1.1% of the administered dose, respectively).
Effects of ganglionic blockade by hexamethonium on blood pressure responses to histamine
Authors: Hilton James G.
Published: December 2017

The effects of blockade of the autonomic ganglia by administration of hexamethonium on blood pressure responses to histamine were studied in the dog anesthetized with sodium pentobarbital. A series of graded doses of histamine acid phosphate were administered before and after the blockade of the ganglia, and blood pressure responses elicited by these doses of histamine were analyzed for minimum attained blood pressure and actual fall and duration of fall in blood pressure. In all cases the minimum attained blood pressure was lower after administration of the ganglionic blocking agent than before. The amount of lowering of the minimum attainable blood pressure was about the same as that of lowering of the control blood pressure produced by the ganglionic blocking agent. Actual fall in blood pressure was unaffected by administration of the ganglionic blocking agent but duration of the fall following all the larger doses of histamine was markedly prolonged by this same procedure. Prolongation of depressor response and lowering of minimum attained blood pressure seem to be more related to the presence or absence of autonomic nervous activity than to the level of control blood pressure.
In vitro uptake of I131 by mammary tissue
Authors: Maqsood M. , Reineke E. P.
Published: December 2017

In vitro uptake of I131 by lactating rat mammary tissue, incubated at 37°C for 6 hours, was 10–15 times that of liver, muscle or boiled mammary tissue. Uptake was greatly reduced by thiouracil and blocked by KSCN, NaCN or incubation under N2. It was increased to about twice the level observed in fresh mammary tissue after storage overnight at 7° C, but decreased rapidly during storage (with penicillin) at 37°C. I131 uptake by fresh mammary tissue was low during early pregnancy and increased sharply from 15 to 20 days of gestation. It increased further during lactation and decreased to minimal values after 10 days of mammary involution. Significant I131 uptake also occurred in lactating mammary tissue of mouse, guinea pig, rabbit and cow. Incubation of lactating rat mammary tissue with varying concentrations of prolactin, TSH, growth hormone, insulin or hydrocortisone had no effect on its I131 uptake. The data indicate that a simple enzyme system, not closely associated with respiratory metabolism, is involved in iodide collection by lactating mammary tissue. Though quite stable at 7°C, it is inactivated by boiling or by storage at 37°C.
Substrate requirements for ion transport by rat intestine studied in vitro
Authors: Gilman Alfred , Koelle Ethol S.
Published: December 2017

Ion transport by the jejunum and ileum of the rat was studied in vitro by a technique which presented a fluid of constant composition (Krebs-bicarbonate) to the mucosal surface of the gut over a period of 2 hours and permitted the direct collection of the transported fluid. Fluid transported by the jejunum was isosmotic with the mucosal fluid but had a lower concentration of Na, K and Cl and a higher concentration of HCO3. The jejunum exhibited a very high rate of aerobic glycolysis and large amounts of lactate were present in its serosal fluid. Fluid transported by the ileum closely resembled the mucosal fluid in composition except for the partial replacement of bicarbonate by lactate. The rate of glycolysis was much lower in the ileum. When the glucose in the mucosal fluid was replaced by citrate or pyruvate, transport practically ceased in the jejunum but was little affected in the ileum. It was concluded that glycolysis provides an obligatory source of energy for ion transport by the jejunum.
A requirement for glucose by excised working rat diaphragm
Authors: Neptune E. M. , Foreman D. R. , Reish J. J.
Published: December 2017

Diaphragm will contract vigorously in vitro for several hours if glucose is present in the medium. In the absence of glucose contracting diaphragm becomes fatigued. Short-chain fatty acids, ß hydroxybutyrate and acetoacetate could not be substituted for glucose to maintain working diaphragm. There is no significant change in the endogenous fatty acids of diaphragm at the end of a period of work. Glycogen synthesis and degradation appear to have no consistent role in the metabolic events occurring during active work.
Effect of cortisone, thyroxine and cold on femurs of guinea pigs
Authors: Sobel Harry , Bonorris George , Sideman Martin
Published: December 2017

The femurs of guinea pigs were analyzed for total mineral, collagen and hexosamine contents following daily administration of 25 µg of l-thyroxine and/or 60 mg/kg of cortisone acetate for 30 days. As judged from values predicted from femur length, cortisone markedly inhibited growth; mineral and hexosamine contents were consistent with growth, and collagen content was greater than predicted. Thyroxine did not reduce growth of femurs but caused less of its constituents to be deposited. Animals exposed to 2°–4°C for 90 days demonstrated a growth pattern and femur composition similar to that observed in thyroxine-treated animals. When cold-exposed animals were returned to room temperature and permitted to attain the weight of the unexposed controls, even though femur length was as great or greater, mineral, collagen and hexosamine contents were below the predicted values.
Physiological effects of extremely high X-ray intensities and dosages on mice
Authors: Moos W. S. , Mason H. C. , Counelis M.
Published: December 2017

The physiological effects of high-intensity x-irradiation (2 x 105 r/min.) and dosages of 1 x 106 r on mice (head and abdomen) were investigated. An increase in pulmonary and heart rates were observed. Electrocardiographic recordings after irradiation demonstrated reversal of wave components and increase of amplitudes. Blood counts present no changes except for a drop in leukocyte counts. Hemoglobin remained unchanged. A considerable increase in serum potassium was noted and some indications of methemoglobin production. Head-irradiated animals yielded a higher incidence of auricular congestion and brain hemorrhage in contrast to animals receiving abdominal irradiation.
Potassium ions and electrical activity of specialized cardiac fibers
Authors: de Mello Walmor Carlos , Hoffman Brian F.
Published: December 2017

Records of the transmembrane potentials of single fibers in isolated preparations of rabbit atrium show that the specialized fibers of the sinoatrial and atrioventricular node as well as latent pacemaker fibers in the crista terminalis are less sensitive to excess potassium than are atrial muscle fibers. Excitability of these fibers is maintained at potassium concentrations which render the remainder of the atrium inexcitable. Measurements of the potassium content and resting potential of these fibers in solutions containing varying concentrations of K+ suggest that the membrane permeability of the specialized fibers may be quantitatively different from that of atrial muscle.
Fatty acid oxidation by mitochondria from cold-fasted rats
Authors: Masoro E. J. , Porter Edith
Published: December 2017

Page 634: E. J. Masoro and Edith Porter, "Fatty acid oxidation by mitochondria from cold-fasted rats." Footnote to table 1 should read: Values are means ± standard deviation of the mean.
Stereotaxic measurements of the calvarium of Macaca mulatta
Authors: Valenstein Elliot S. , Beer Bernard
Published: December 2017

Stereotaxic measurements of the calvarium of the skulls of 40 rhesus monkeys were made, grouping data in five weight classes. Recording was made of distances in millimeters between the top of the calvarium and Horsley-Clarke, horizontal zero. This information permits the utilization of electrodes cut and attached to an anchoring pedestal prior to the time of surgery. Such a procedure considerably shortens the operation time thereby adding convenience and lessening risk. Information on the stereotaxic coordinates of principle skull landmarks as well as length and breadth of skulls from representative weight classes was evaluated.
Curare reveals central rather than peripheral factor determining cardiac orienting reflex
Authors: Newton Joseph E. O. , Gantt W. Horsley
Published: December 2017

The purpose of these experiments was to determine to what extent the cardiac acceleration ordinarily associated with the movement to a novel stimulus (orienting reflex) or to a conditional reflex (pain or food) is dependent upon the accompanying muscular movement and to what extent upon the CNS excitation. In dogs previously studied, curare was given to eliminate or diminish the movement. An auditory stimulus (bell) was used to elicit the orienting reflex in both controls and curarized animals. Motor components that were seen normally were abolished or greatly diminished. In spite of the lack of movement, however, the cardiac acceleration to the bell was approximately the same under curare as without curare. Our conclusion is that the cardiac component in the orienting reflex to novel stimuli is primarily a result of CNS excitation and not due to the degree of muscular movement.
Plasma proteins in the blood of fishes from the Gulf of Mexico
Authors: Sulya L. L. , Box B. E. , Gunter Gordon
Published: December 2017

The plasma proteins of 14 families and 26 species of fishes from Gulf coast marine waters have been studied electrophoretically. Analbuminemia has been observed not only in elasmobranchs, but in gars and some clupeids, as well as in two species of higher fishes. Analbuminemia is characteristic of the lower fishes and gradually disappears as fishes become more complex, but not entirely, since the condition exists in a few higher fishes. In addition, several species were lacking in the alpha-1-globulin fraction. There is an increase in complexity of plasma proteins from lower to higher fishes. The plasma proteins show specific differences and may be quite different in closely related fishes. The total plasma protein is lower than in mammals.
Initiation and abolition of electric response of nerve fiber by thermal and chemical means
Authors: Spyropoulos C. S.
Published: December 2017

Techniques were developed to produce brief pulses of temperature variation or pulses of variation in the chemical composition of the medium surrounding the node of nerve fibers of the toad ( Bufo marinus). The effect of such changes were studied upon the nodal response. The response was prolonged by addition of a small amount of Ni ion to the medium and/or by making the Ringer's hypertonic by addition of NaCl. Application of a pulse of temperature rise during the plateau of a response resulted in abolition of the response. A pulse of rise in the concentration of Ca ion in the medium also brought about abolition. Sudden cooling, sudden removal of Ca ion from the medium or a sudden rise in the K-ion concentration during the plateau of the response resulted in prolongation of the response; in some instances, the process of repolarization was completely prevented by these procedures. In the node at rest, sudden cooling or a sudden rise in the K-ion concentration in the medium initiated a full-sized response in an all-or-none manner.
Irreversible hemorrhagic shock in dogs: structure and function of liver mitochondria
Authors: Hift H. , Strawitz J. G.
Published: December 2017

Paired experiments were conducted with dogs dying in irreversible hemorrhagic shock and with normal controls. Examined under the electron microscope the liver cells from the experimental dogs were found to contain enlarged mitochondria characterized by a swollen matrix, rather than an altered double-membrane structure. Swollen, abnormal particles were also observed under phase contrast in whole-tissue blendorates and purified mitochondrial suspensions derived from such livers. Simultaneously, slices and purified suspensions prepared from those livers yielded higher than normal oxygen uptakes but normal P/O ratios and the purified mitochondria were found to contain normal proportions but excessive amounts of proteinous, nitrogenous and UV-absorbing material. It is suggested that liver mitochondria adjust to the stress imposed by the prolonged oligemia and hypoxia by enlarging and acquiring an extra complement of Krebs' cycle enzymes. The liver may thus be in a state of potential hyperactivity at a time when the animal as a whole is succumbing to the effects of irreversible hemorrhagic shock.
Blood flow and oxygen consumption of the pregnant uterus
Authors: Huckabee William E. , Metcalfe James , Prystowsky Harry , Barron Donald H.
Published: December 2017

The 4-aminoantipyrine method was employed for measuring rate of blood flow per kilogram of tissue in the pregnant uterus of anesthetized goats. A uterine vein was cannulated, but no other manipulation or disturbance of the uterus occurred. Uterine blood flow was high in the nonpregnant uterus and in early pregnancy but fell to a plateau of 277 ml/kg/min. at midpregnancy. (A-V)O2 was minimal in the first quarter of pregnancy and rose to a plateau also by midpregnancy. Rate of O2 consumption per kilogram was relatively high in the nonpregnant uterus, fell to a minimal value in the first quarter of the gestational period, and rose again to a plateau of 10.1 ml/kg/ min. beginning at midpregnancy. All these values appeared to remain unchanged during the last half of gestation.
Identification of a reticuloendothelial stimulating agent in zymosan
Authors: Riggi S. J. , Di Luzio N. R.
Published: December 2017

The functional activity of the reticuloendothelial system (RES), as determined by the intravascular clearance of colloidal carbon, and the degree of induced RE hyperplasia were studied following the intravenous injection of various constituents of zymosan. The readily extractable lipid component from the yeast cell wall was inactive, as was the polysaccharide, mannan. Stimulatory activity was still present in the zymosan residue after removal of free and bound lipids. The administration of glucan derived either from yeast, or its cell wall, resulted in marked RE activation and induced hyperplasia, demonstrating it to be the active RE stimulating agent. The relationship of glucan's chemical structure to its ability to induce RE hyperfunction and hyperplasia is discussed.
In vitro absorption of bile salts by small intestine of rats and guinea pigs
Authors: Lack Leon , Weiner I. M.
Published: December 2017

The transport of taurocholic and glycocholic acids by the small intestine of rats and guinea pigs against a concentration gradient was studied by the everted gutsac technique. Transport of these substances is limited to the distal ileal segment. This transport is inhibited by anoxia, dinitrophenol and sodium azide. The system has a transport maximum. On the basis of these criteria bile acid reabsorption is considered to occur by active transport.
Plasma calcium distribution in relation to parathyroid function
Authors: Breen Moira , Freeman Smith
Published: December 2017

The plasma calcium was fractionated into protein-bound and free fractions by means of an ultracentrifuge in normal, hypoparathyroid and hyperparathyroid dogs and normal and hypoparathyroid rats. The proportion of the total plasma calcium that was diffusible was greater in normal and hypercalcemic animals than in the hypoparathyroid state. Recalcification of hypoparathyroid dog plasma in vitro gave a similar calcium distribution to that obtained when parathyroid extract was injected into hypoparathyroid dogs. Although the binding of calcium per gram of plasma protein increased both in vivo and in vitro as the concentration rose, the results did not conform to the simple mass law relationship as usually expressed. The evidence presented indicates that parathyroid function only influences the distribution of plasma calcium indirectly by regulating its concentration.
Changes in kidney enzymes of rats after birth
Authors: Wacker Glenda R. , Zarkowsky Harold S. , Burch Helen B.
Published: December 2017

Alkaline phosphatase, glutaminase, carbonic anhydrase and protein were measured in whole kidney homogenates of newborn, 4-, 9-, 14-, 21-, 33-, 44-, and 56-day-old rats. From birth to 21 days there is little change in glutaminase and carbonic anhydrase. At 21 days there is approximately a twofold increase. Adult levels, which are, respectively, four- and sixfold greater than at birth, were measured at 56 days. Alkaline phosphatase decreases from birth to 14 days. At 21 days newborn values are again reached and a threefold rise occurs between 21 and 33 days. Adult females had higher renal concentrations of all three enzymes than adult males.
Phrenic nerve-diaphragm preparations in relation to temperature and hibernation
Authors: South Frank E.
Published: December 2017

Electrical and mechanical properties, as correlates of incubation temperature, of phrenic nerve-diaphragm preparations obtained from hibernating and control hamsters and from rats were examined. Six incubation temperatures, ranging from 5° to 38°C, were used. Nerves of rats evidenced much steeper temperature functions than did either hamster group, with respect to irritability, spike voltage and conduction velocity such that they were inexcitable at 5°C. The hibernating and control hamster groups behaved quite similarly to each other in these respects. Neuromuscular blockade occurred at 10°C in the rat preparations and at 5°C of the control hamster preparations but in no case did it occur among those of hibernating animals. Similar or analogous differences were apparent in diaphragm muscle tissues insofar as irritability, tension production and rates of contraction and relaxation are concerned. These observations were taken to demonstrate the existence of phylogenetic adaptations correlated with the ability of hamsters to hibernate as well as the probable necessity for a prehibernal acclimatization of such mechanisms as neuromuscular transmission on the part of these animals.
Renal hemodynamics and sodium excretion in dogs with graded valvular damage, and in congestive failure
Authors: Barger A. C. , Yates F. E. , Rudolph A. M.
Published: December 2017

In an attempt to study the sequence of renal changes which occur with progressive cardiac impairment, renal plasma flow, glomerular filtration rate, sodium and water excretion were investigated in a group of dogs in the normal state, following the production of tricuspid insufficiency, and then after the superimposition of pulmonary artery stenosis, and the development of frank failure. With mild valvular damage basal CCr was unchanged, rose or fell slightly, while CPAH usually was decreased. At this stage the renal response to a rapid saline infusion was sluggish; CCr, CPAH, sodium and water excretion rose approximately 50% of normal. In frank failure basal CCr was unchanged from control levels, or only slightly reduced until late in the course of the disease. Basal CPAH was markedly reduced in all the dogs, with filtration fraction rising to 0.38 in three dogs. Saline infusion produced little or no rise of CCr and CPAH, and salt and water retention was nearly complete. It is postulated that the early decrease in renal blood flow, and the sluggish response to a saline infusion is the result of increased sympathetic nervous activity in the kidney, and is part of baroreceptor reflex tending to restore the circulation toward normal.
Passage of labeled albumin into canine aortic wall in vivo and in vitro
Authors: Duncan Leroy E. , Buck Katherin
Published: December 2017

The passage of labeled albumin into canine aortic wall in vivo and in vitro was studied. In vivo albumin entered the inner layer fastest in the ascending aorta and progressively less rapidly down the length of the aorta. In vitro, this gradient was partially preserved since albumin entered the inner layer of ascending aorta faster than that of descending aorta. The gradient was not completely preserved in vitro, since albumin entered the inner layer of abdominal aorta faster than that of descending thoracic aorta. The rapid entrance of albumin into the abdominal portion of the aorta in vitro appears to have been due to the maintenance of arterial blood pressure in the unusually dense capillary network of the abdominal aorta. The partial preservation of the gradient in the isolated aorta excludes phasic variation of intra- or extra-aortic pressure as a cause of the gradient.
Muscle afferents and activity of respiratory neurons
Authors: Koizumi K. , Ushiyama J. , Brooks C. McC.
Published: December 2017

Respiratory effects of stimulating afferent fibers of muscle, skin and mixed nerve were determined in Nembutal-anesthetized cats. Repetitive stimuli which produced only monosynaptic reflex actions caused augmentation of respiration. When stronger stimuli also activated fibers of a smaller diameter than group I afferents, polysynaptic reflexes were evoked and greater changes in respiration resulted. Volume rather than rate changes were induced by stimulation of these muscle afferents. Microelectrodes were used to record from respiratory neurons of the medulla and pons. Most neurons fired in conjunction with inspiration; stimulation of muscle afferents advanced time of firing and increased frequency of discharge. Neurons firing in conjunction with expiration were inhibited by muscle afferents. A few neurons of the pons showed respiration-linked activity modified by afferent nerve stimulation. Segmental reflex discharges, out intercostal nerves, elicited by dorsal root stimulation were found to be inhibited by stimulation of muscle afferents. Discharges from muscle receptors affect ventilatory volumes and activities of medullary neurons which seemingly participate in the control of respiration.
Deficits of temperature regulation in rats with hypothalamic lesions
Authors: Han Paul W. , Brobeck John R.
Published: December 2017

Temperature regulation was studied in rats with bilateral hypothalamic lesions, by observing body temperature responses to the heat stress of forced exercise, and to exposure to hot or cold environments. Lesions in the preoptic area caused impairment of heat loss mechanisms but no disturbance of regulation against cold. Lesions in the lateral hypothalamic area caused no disturbance of regulation against cold; regulation against heat exposure was also not significantly altered, but the cause of a higher T-cut observed after exercise could not be explained. Lesions in other parts of the hypothalamus, with the exception of the ventromedial nuclei, did not cause changes in the normal pattern of temperature response to forced exercise.
Effects of ouabain, hypothermia and anoxia on cation fluxes in embryonic chick heart
Authors: Klein Richard L. , Evans M. L.
Published: December 2017

An active cation transport mechanism is believed to exist in embryonic chick myocardium by at least 2 days incubation. Classical effects of ouabain on unidirectional Na and K movements and contents are demonstrated in isolated ventricles of the developing embryo and hatched chick. In addition to inhibiting active Na extrusion and K entry, a marked stimulation of a passive Na in-K out exchange mechanism is indicated. Ouabain's actions on Na and K movements are believed to be primarily toxic manifestations. Hypothermia inhibits K influx and efflux equally between 30° and 20°C. Not until temperatures of 10° and 5°C are reached do Q10's for influx become greater than for efflux. Effects of anoxia on cation movements in young embryos are small, but increase greatly at older ages. Active transport of Na and K is sensitive to ouabain and relatively insensitive to hypothermia at all ages tested. It is relatively insensitive to anoxia at early ages. Changes in ventricular cation content are given for all conditions.
Common carotid artery occlusion reflex in unanesthetized dogs
Authors: Armstrong G. G. , Porter H. , Langston J. B.
Published: December 2017

The quantitative changes in systolic pressure, diastolic pressure, mean pressure and pulse rate produced by 128 bilateral occlusions of the common carotid arteries in nine conscious dogs are reported. The average of the values measured before occlusion were: systolic pressure, 176 mm Hg; diastolic pressure, 80 mm Hg; mean pressure, 117 mm Hg; pulse rate, 101 pulses/min. Increases of 28%, 50%, 39%, and 28%, respectively, were obtained as a result of the occlusions.
Circadian studies on succinic dehydrogenase pantothenate and biotin of rodent adrenal
Authors: Glick David , Ferguson Robert B. , Greenberg Leonard J. , Halberg Franz
Published: December 2017

Coenzyme A concentration and the activity of the succinic dehydrogenase system in rodent adrenals are both circadian periodic functions; both apparently can be synchronized with a 24-hour periodic regimen of alternating light and darkness. Such light-synchronized periodicity analysis reveals that circadian changes in succinic dehydrogenase activity are roughly in phase with changes in serum corticosterone and, perhaps, also in phase with the corticosterone rhythm of the adrenal itself. The circadian rhythm of adrenal CoA, in turn, shows a significant phase difference when compared either to corticosterone concentration or to the activity of the succinic dehydrogenase system. Circadian periodic changes in total biotin concentration in adrenals of rats and mice were not detected.
Oxidative phosphorylation and related reactions in liver mitochondria from diabetic dogs
Authors: Beyer Robert E. , Shamoian Charles A.
Published: December 2017

Oxidative phosphorylation, dinitrophenol- and Mg++-activated adenosinetriphosphatase and the adenosinetriphosphatein-organic orthophosphate exchange reaction were studied in mitochondria isolated from livers of chronic and acutely diabetic dogs. Although such reactions are readily demonstrable in these preparations, no trends indicating a deficiency of the energy-conservation reactions studied in preparations from diabetic dogs were noted. In addition, electron transport rates with glutamate or succinate as substrate were increased in the diabetic preparations, as was the yield of mitochondria from such animals. This is not in agreement with recently published reports concerning related studies on diabetic cats and rats. The above findings indicate that a metabolic defect in the efficiency of oxidative phosphorylation is not a general primary lesion in the diabetic syndrome.
Cardiac glycogen of rats during and following acute anoxia
Authors: Meyer Dallas K. , Purdy Ferrill A.
Published: December 2017

Cardiac glycogen, both free and bound, was determined in rats at two stages of acute anoxia and six stages of recovery from anoxia. The glycogen was subjected to ß amylase digestion to obtain the limit dextrin of each sample. Free and bound cardiac glycogen are both depleted by anoxia. Resynthesis is rapid, control levels being restored within 40–60 minutes. The overshoot in total glycogen after anoxia is shown to be due to the free glycogen alone. Free and bound glycogen exhibit structural differences during anoxia and during recovery from anoxia. Branching activity during resynthesis is complete for free glycogen within 1 hour but the bound glycogen shows internal transglucosidation that continues for more than 3 hours but less than 15 hours. The data reveal that the structure of glycogen is a reflection of the physiological state of the animal and that free and bound glycogen may have a real physiological significance.
Effect of ouabain on potassium exchange in the mammalian heart
Authors: Schreiber Sidney S. , Oratz Murray , Rothschild Marcus A.
Published: December 2017

The effect of the digitalis glycoside, ouabain, on potassium exchange in the guinea pig heart in vitro was studied with the aid of K42. With modified Ringer's solution as a perfusate at 38 C, K was found to exchange at two rates in both washout and buildup studies. In vivo equilibration studies also suggested more than one rate of exchange. Ouabain, in vitro, effected inhibition of entrance of K into the slowly exchanging compartment, but did not affect influx into the fast compartment or efflux from the fast or slow compartments. The ouabain inhibition was seen at Ringer's K concentrations of 3.8–4.3 mEq/liter was equivocal at K concentrations of 5.0–5.5 mEq/ liter and absent at K concentrations of 7.0–7.5 mEq/liter. It was postulated that ouabain inhibition was directed toward the slowly exchanging fraction of intracellular potassium.
Transport and exchange diffusion of l-tryptophan in Ehrlich cells
Authors: Jacquez John A.
Published: December 2017

The initial velocity of uptake of l-tryptophan by Ehrlich ascites cells can be explained as the sum of two processes: diffusion and an active transport that shows a saturation effect. Azaserine, l-2,4 diaminobutyric acid, l-histidine, and l-leucine, at low concentrations, increase the initial velocity of uptake of l-tryptophan but compete with l-tryptophan at high concentrations. Preliminary loading of the cells with glycine decreases the initial tryptophan flux: preliminary loading of the ascites cells with azaserine or tryptophan markedly increases the initial flux of uptake of the other amino acid.
Myocardial blood flow in the rabbit
Authors: Grayson J. , Mendel D.
Published: December 2017

Internal calorimetry was applied to the study of blood flow in the rabbit myocardium. In the normotensive animal resting flow per unit mass of tissue was about double that in the liver. Blood flow was a linear function of mean systemic blood pressure. Autoregulation was not a property of the myocardial vasculature, nor was there any trace of spasmodic closure of vessels at low pressures (critical closing). Under conditions of stabilized blood pressure, adrenaline and noradrenaline reduced myocardial blood flow. Acetylcholine, which in the present experiments did not slow the heart, produced a rise in myocardial blood flow when the blood pressure was stabilized.
Effect of zymosan on dogs subjected to hemorrhagic hypotension
Authors: Blattberg Benjamin , Levy Matthew N.
Published: December 2017

Injection of zymosan intravenously, or subcutaneously in combination with adjuvants, increased the survival rate of dogs subjected to hemorrhagic hypotension ( P = <0.04). As a result of the zymosan injections, properdin titers were increased by more than 25% in 14 of 24 dogs. Of the animals with significantly increased properdin levels, 71% survived. Only 30% of dogs survived in a group in which the properdin titer did not rise. This mortality rate is virtually identical with a control series of animals which were similarly treated, but which did not receive zymosan.
Cardiac adrenergic blockade with DCI in the intact unanesthetized animal
Authors: Van Citters Robert L. , Baker Donald , Rushmer Robert F.
Published: December 2017

Using techniques developed in this laboratory for continuous recording of essential parameters of left ventricular function, the cardiovascular responses of intact unanesthetized animals to intravenous infusions of isoproterenol, epinephrine and norepinephrine, and to exercise and hypothalamic stimulation, have been compared with responses to the same drugs and procedures after adrenergic blockade, first with the dichloro analogue of isoproterenol (DCI), and then with both DCI and phenoxybenzamine. At dosage level of 5 mg/kg, DCI effectively blocked the response to isoproterenol, but had less effect on the response to epinephrine and norepinephrine, and no effect on the response to exercise or central stimulation. The effects of DCI, per se, were dosage-dependent.
Changes in myocardial composition after coronary artery ligation
Authors: Russell Raymond A. , Crafoord Joar , Harris A. Sidney
Published: December 2017

Myocardial infarction was produced by ligation of the coronary artery in a series of 20 dogs, which were killed 1, 4 1/2, 12, or 24 hours later. Each heart was divided into three parts: the infarcted area, the undamaged area, and a border zone including some of each. Each part was analyzed for its content of sodium, potassium, epinephrine, norepinephrine, and water. The water content of the infarct is detectably higher within 1 hour, reaching its ultimate concentration more rapidly than do the other changes seen. Potassium is lost from the infarct and replaced by sodium. The catecholamines progressively decrease in concentration within the infarct during the first 24 hours. No evidence of selective accumulation or loss of any of these constituents in the border zone was noted, although this zone appears to trigger the ventricular arrhythmia that occurs after coronary occlusion. The possible roles of potassium, epinephrine, and norepinephrine, as agents excitatory to such tachycardia, are discussed.
Vasoactive agents in portal blood during hemorrhagic shock
Authors: Rothe Carl F. , Selkurt Ewald E.
Published: December 2017

Vasoactive agents released from the intestine during hemorrhagic shock in dogs were studied by perfusing either an isolated terminal loop of ileum or an isolated gracilis muscle with oxygenated portal blood at 100 mm Hg pressure. At 10–20-min intervals femoral arterial blood at 100 mm Hg pressure was used as the perfusate to evaluate changes in the preparation and release of vasoactive agents into the systemic blood supply. By the end of the 40 mm Hg hypotensive period, vasodilators were consistently found in the portal blood. After transfusion of the shed blood, vasoconstrictors usually seen in the arterial blood during the hypovolemic phase were replaced or masked by vasodilators. However, during the remainder of the normotensive period, vascular tone slowly returned to near normal using either source. Terminally, vasodilators were often seen in both arterial and portal blood. Results with muscle were similar to those using an intestinal loop. Although the degree and pattern of vasodilatation do not appear to be adequate to explain the eventual circulatory collapse, it is suggested that the vasodilatation during the last phase of hypovolemic hypotension may be indicative of the release of agents which act on the cardiovascular system to contribute to irreversibility.
Effect of insulin on potassium transfer in isolated rat liver
Authors: Mortimore Glenn E.
Published: December 2017

The effect of insulin on the net transfer of potassium between the isolated, cyclically perfused, fasted rat liver and the perfusate was studied. In the absence of insulin approximately 7.5% of liver potassium was lost into the serum during 60 min of perfusion. Insulin, at concentrations of 1.2 and 3.0 x 10–10 m (mol wt 6,000), inhibited this release. Maximal inhibition (93% at 10 min) was elicited with insulin levels of 1.2 x 10–9 m and greater. A comparison of liver weights at the end of the perfusions revealed that the control livers were significantly smaller than those treated with insulin. No difference in the concentration of liver potassium between these two groups was found. From these data, together with the results of liver water determinations, it was tentatively concluded that, in addition to potassium, water was also released by the liver cell. Although the metabolic significance of these shifts is not clear at present, their inhibition by low concentrations of insulin strongly suggests a physiological role for insulin in the maintenance of liver potassium and water.
Influence of coronary perfusion and myocardial edema on pressure-volume diagram of left ventricle
Authors: Cross Cecil E. , Rieben P. Andre , Salisbury Peter F.
Published: December 2017

Pressure-volume diagrams of paced, isolated hearts were derived from isovolumic contractions and auxotonic contractions (simultaneous changes of pressure and volume). Coronary perfusion, fluid accumulation in heart muscle, and left ventricular volume and pressure were measured and controlled. Pressure-volume diagrams from isovolumic and auxotonic contractions were virtually identical in the same heart and were influenced by the same factors to a similar degree. At equal diastolic volumes the magnitude of systolic, as well as of diastolic pressures, and the occurrence of a systolic descending limb were directly related to coronary perfusion pressure. At equal diastolic volumes, other factors being constant, myocardial edema did not influence the contractile strength (i.e., maximum contractile tension development) of a ventricle, but did decrease its distensibility (i.e., increase diastolic pressure) in proportion to fluid accumulation. Myocardial water content and coronary factors (coronary arterial and venous pressures, coronary blood volume and flow) therefore constitute intrinsic mechanisms which can regulate the performance of a ventricle by changing its contractile strength, its distensibility, or both. The effects of coronary factors and of myocardial edema on the distensibility of a ventricle are sufficient in magnitude to explain hemodynamic abnormalities which characterize certain types of congestive heart failure.
Sodium conservation and control of glomerular filtration rate
Authors: Blake William D.
Published: December 2017

Experiments on dogs were designed to study the role of glomerular filtration rate (creatinine clearance, CCr) in sodium homeostasis. Dogs were studied on a normal Na intake (salted) and after Na had been removed from the diet (unsalted). In both instances CCr was estimated before and after rapid expansion of extracellular fluid volume (ECF) with glucose, mannitol, or NaCl solutions. Before expansion of ECF, CCr showed no consistent change relating to Na-deficiency as such. Following expansion of ECF, CCr increased in dogs with normal intake of Na and decreased (or increased less) in nine out of ten comparisons in dogs with no Na in the diet. The percentage change in CCr elicited by ECF expansion correlated positively with change in plasma Na concentration and inversely with change in plasma potassium concentration, except following NaCl solution infusion or the inclusion of K in glucose infusions. Decreased CCr following ECF expansion in dogs with no Na in the diet was tentatively ascribed to intrarenally evoked vasoconstriction consequent to the loss of intracellular K from some undefined site.
Interrelationships of diet and cold exposure on selected liver glycolytic enzymes
Authors: Vaughan David A. , Hannon John P. , Vaughan Lucile N.
Published: December 2017

The effect of a 28-day cold exposure (4 ± 1 C) on selected glycolytic enzymes of the liver was studied in rats subsisting on carbohydrate free diets high in fat or protein and on a 65% glucose diet. Cold exposure increased glucose-6-phosphatase activity on all diets, but had an appreciable effect on glucokinase activity only in the rats fed high carbohydrate diets. The activity of phosphorylase was not affected by cold. "Pyruvate formation," like glucose-6-phosphatase activity, was increased significantly in all dietary groups by cold exposure. The extremely low activity of glucose-6-phosphate dehydrogenase in the rats fed high fat diets was unaffected by cold exposure. These results are interpreted to mean that, on a carbohydrate free diet, imposition of cold leads to increased reversal of pyruvate formation which is reflected in increased production of free glucose, whereas hexose monophosphate shunt activity and glycogenesis remain unaffected. Even on a high carbohydrate diet, the capacity for hepatic glucose production appears to be increased, possibly as a result of increased periodic demands on the part of extrahepatic tissues.