bluuebunny/crossref_metadata_2025 huggingface dataset:
An electroencephalograph study of classical conditioning
Authors: Galambos Robert , Sheatz Guy C.
Published: December 2017

Unanesthetized monkeys and cats bearing indwelling electrodes show electrical activity evoked by clicks and light flashes in regions such as caudate nucleus, hypothalamus, and limbic system as well as in the classically defined sensory pathways. Amplitude and duration of the evoked responses, which display a similar triphasic form wherever recorded, vary spontaneously but can be experimentally enhanced by reinforcement or reduced by extinction in a simple Pavlovian conditioning procedure. When an animal displaying large responses to click stimuli appears to attend to a simultaneous visual stimulus (distraction) the click-evoked activity is remarkably reduced. Both wave shape and lability of the responses are preserved despite paralysis produced by a curare-like drug and (at auditory cortex) cutting the auditory pathway bilaterally at the midbrain level. Relevance of these results to some previous studies on learning is discussed, along with the possible relationship of these data to the neurophysiological findings reported on anesthetized preparations.
Renal disposal of salicyluric acid
Authors: Knoefel P. K. , Huang K. C. , Jarboe C. H.
Published: December 2017

Physical properties and disposal by the dog's kidney of salicyluric ( o-hydroxyhippuric), p-hydroxyhippuric, 3-nitrohippuric, and 3- and 5-nitrosalicyluric acids have been measured. All undergo renal tubular excretory transport, but also tubular reabsorption to a varying degree, depending on their lipoid solubility, which property is greater in the salicyluric acids as a result of internal hydrogen bonding. Both bonded and free forms are present; it is probable that it is the bonded form which is reabsorbed passively; which form(s) is secreted cannot be stated.
Swimming stress and adaptation by dystrophic and normal mice
Authors: Soltan Hubert C.
Published: December 2017

Dystrophic mice, 5–11 weeks old, from the inbred strain 129/ Re- dy and from the cross between 129/Re- dy and the stock C57BL/6-Miwh/Re swam more slowly than normal littermates. For both normal and dystrophic mice the reduction in swimming speed after forced swimming stress was most marked in the first days of the new experience. No difference was detected in the swimming speeds of DyDy as compared with Dydy mice. But mice of both genotypes swam more rapidly when the temperature of the water was lowered from 95 F to 68 F.
Vitamin D3 and unidirectional calcium fluxes across the rachitic chick duodenum
Authors: Wasserman R. H. , Kallfelz F. A.
Published: December 2017

The effect of vitamin D3 on the unidirectional fluxes of calcium across the chick duodenum in vivo was studied. As the calcium concentration in the lumen was enhanced it was observed that both calcium efflux (lumen to plasma) and calcium influx (plasma to lumen) were increased in the rachitic and vitamin D3-treated chick. Of significance, it was found that vitamin D3 caused an increased efflux as well as increased influx of calcium, and the observed efflux/influx ratios at all levels of intraluminal calcium were not significantly affected by vitamin D3. The present data are not consistent with the theory that vitamin D3 operates through a unidirectionally oriented active transport system but can be more readily explained on the basis of a permeability change at the mucosal cell.
Free fatty acid concentration and composition in arterial blood
Authors: Rothlin Martin E. , Rothlin Christine B. , Wendt Vernon E.
Published: December 2017

The effect of the administration of norepinephrine, glucose and insulin, pentobarbital, and Hypertensin on the arterial concentration and composition of plasma free fatty acids (FFA) has been studied in man and dog. With a rise of the FFA concentration as produced by norepinephrine, the contribution of oleic acid to the total FFA increased, while that of stearic and palmitic acids decreased. The reverse changes in the FFA composition were observed when their arterial level fell under the influence of other agents studied. The FFA composition was dependent on the FFA concentration in arterial blood, but not on the experimental condition of the subject or animal at the time of analysis. At high FFA levels, the FFA composition approached that of depot fat.
Utilization of free fatty acids by diaphragm in vitro
Authors: Bodel P. T. , Rubinstein D. , McGarry E. E. , Beck J. C.
Published: December 2017

Human and rat diaphragm and rat gastrocnemius muscle oxidize and esterify palmitate-1-C14. Incorporation of C14 was found to be in proportion to the palmitate present in the medium over a range of concentrations from 0.8 to 2.9 µEq/ml. Fasting increased C14O2 production but had no effect on esterification. Iodoacetate or an atmosphere of nitrogen inhibited esterification of palmitate but increased the amount of free fatty acid in the tissue. Insulin increased esterification, and this was enhanced by the addition of glucose. Glucose and insulin exerted a sparing action on the oxidation of glycerides by a tissue previously charged with palmitate-1-C14. Growth hormone administered in vivo over a period of 1 week or in vitro during incubation had no effect on esterification or metabolism of palmitate-1-C14.
Lipolytic activity in rat epididymal fat pads
Authors: Björntorp Per , Furman Robert H.
Published: December 2017

Rat epididymal fat pads were incubated in the presence of heparin and epinephrine. The lipase activity present in the incubation medium and in the tissue after homogenization was measured, partially purified, and characterized. A lipase was eluted into the incubation medium which was considered to be identical with lipoprotein lipase described by E. D. Korn. It had a pH optimum of 8.5, required serum proteins and ammonium sulfate as cofactors, and was inhibited by high ionic strength, protamine sulfate, EDTA, and deoxycholate. The yield of this lipase was greater when heparin was present in the incubation medium and when the pads were obtained from fed rather than fasting rats. This lipase was also present in the tissue homogenates. A lipase differing from lipoprotein lipase was found in the tissue homogenates. It had a pH optimum between 6.5 and 7 and required albumin for optimal activity. It was inhibited by NaF. The yield of this lipase was greatest in the homogenates of fat pads obtained from fasting rats and incubated with epinephrine. Position-specificity tests utilizing a pure triglyceride of known fatty acid composition indicated preferential alpha fatty acid hydrolysis by both lipases as well as by pancreatic lipase.
Olfactory mucosal and neural responses in the frog
Authors: Mozell Maxwell Mark
Published: December 2017

A comparatively recent electrophysiological technique for studying peripheral olfactory events is to record sustained negative potentials from the olfactory epithelium. This method is rapidly replacing the older technique of recording multifiber discharges from the olfactory nerve or bulb. Therefore, the extent to which the results from the two methods correlate with each other was studied by simultaneously recording from the nerve and from the mucosa under several conditions. Although most often parallel, some differences between the two measures were found. Their response maxima did not always temporally coincide. Their amplitudes did not always correlate. Certain stimuli reduced subsequent mucosal responses but not the neural. Repeated stimulation sometimes produced similar differences. Finally, the two responses were not linearly related as a function of stimulus intensity or flow rate. However, for reasons discussed, it is difficult to conclude that these discrepancies necessarily reflect unfavorably upon the reliability of the mucosal potential as the criterion measure of peripheral olfactory activity. Nevertheless, the mucosal potential should not be accepted unequivocally as such a criterion measure until it is more thoroughly understood.
Pressure-diameter relations of the in vivo aorta
Authors: Remington John W.
Published: December 2017

Simultaneous pressure and diameter (using a Peterson transformer coil) pulses were recorded from the aorta, carotid, and femoral arteries of the dog. The pressure-diameter loop showed many points of similarity with that given by excised vessels. Thus the loop was modified by changes in pulse pressure, heart rate, and the number of successive pulses covering the same pressure range. The in vivo loops showed a greater rate of diameter return during stretch-release. Any effect of vasoactive drugs on extensibility was obscured by changes in one or more of the passive factors. Attempts to stimulate the muscle of the aorta directly were ineffectual. A wall stiffening was produced, in a minority of cases, with muscular arteries. As one means of evaluating the physiological significance of the distensibility changes, modifications of the pulse contour technique for calculating stroke indexes were made, based on the usual dimensions of the hysteresis loops. Recalculation of a large number of pulses showed a better fit of derived stroke indexes with those obtained by the Fick procedure.
Response of motor unit of gastrocnemius of the rat to repetitive stimuli
Authors: Locke Simeon
Published: December 2017

The response of the action potential of the single motor unit of the gastrocnemius of the rat to trains of stimuli delivered to a ventral root filament was studied in ten animals. Fractionation of the action potential of the unit into component subunits occurred with trains of stimuli having less than a 5-msec stimulus interval. The anatomical nature of the subunit is not known.
Influence of vitamin D on calcium absorption in the chick
Authors: Sallis J. D. , Holdsworth E. S.
Published: December 2017

The site of absorption of Ca45 was studied in rachitic chicks and rachitic chicks given vitamin D3. Vitamin D3 markedly increases absorption from the small intestine and, in vivo, similar amounts of calcium are absorbed along the entire small intestine. With everted gut sacs, the distal third of the small intestine transported much more calcium than did the duodenal and middle sections. Thus, interpretations of in vitro results may not always depict the natural in vivo process. Vitamin D2 had little activity in the chick, but AT-10 series 2 and AT-10 series 3 were almost as active as vitamin D3 for calcium transport. These results suggest an "active carrier" may be formed by addition of hydrogen or hydroxyl groups to the opened ring B of vitamin D, giving a carrier capable of reversible oxidation-reduction or keto-enol tautomerism. Using metabolic inhibitors, active calcium transport in vitro relied on glycolysis for its energy supply. The transport was independent of the sodium pump.
Electrolyte, urea, and water movements across canine intestinal mucosa
Authors: Annegers John H. , Wakefield Harold
Published: December 2017

Solutions of varying chemical and osmotic composition were perfused through isolated upper or lower bowel loops in unanesthetized dogs. Enterosorption and absorption of solute ions were measured separately and an apparent insorption rate of solutes was estimated. The latter increased nearly linearly with log perfusate concentration. The slope constants (Δ insorption/Δ log conc.) differed among ions and differed for a given substance when certain other ions were present. Insorption rates at a standard solute concentration (100 mm/liter) ranged from 15 mm/hr for urea to .62 mm/hr for calcium (chloride). Sodium and potassium (chloride) rates averaged 4.35 and 3.1 mm/hr, respectively. Water enterosorption increased linearly with log perfusate osmolarity for all perfusates. However, at a standard perfusate concentration (278 mOs/liter), water absorption ranged from 4.3 m/hr for urea to .4 m/hr for CaCl2. Concomitant solute insorption and water absorption rates were correlated significantly.
Relationship between electrical and hydrogen ion gradients across rat proximal tubule
Authors: Bank Norman
Published: December 2017

By means of micropuncture methods, proximal transtubular electrical potentials and tubular fluid pH were measured during isotonic sodium chloride or hypertonic dextrose infusion in normal rats and during sodium ferrocyanide infusion in salt-restricted rats. The mean electrical potential during sodium ferrocyanide infusion was significantly higher than in the other two groups (31.5 mv vs. 18 mv) and the mean tubular fluid pH was significantly lower (6.85 vs. 7.08). This parallel increase in electrical and concentration gradients with sodium ferrocyanide infusion suggests a passive component to hydrogen ion distribution across the tubular cells. Using the Nernst equation, equilibrium potentials were calculated from the observed hydrogen ion gradients. Almost all of these calculated potentials were found to be less than the observed electrical potentials and therefore the distribution of hydrogen ions in these experiments could be accounted for entirely by passive diffusion. It is postulated that poorly reabsorbable anions depolarize the luminal membrane to a greater extent than the peritubular membrane, thereby increasing both transtubular potential and hydrogen ion excretion.
Conductivity changes in some organs after circulatory arrest
Authors: Harreveld A. Van , Biber M. P.
Published: December 2017

A loss of electrical conductivity after circulatory arrest was observed in the submaxillary salivary gland, liver, kidney, and skeletal muscle. A drop in conductivity of 85–90% of the original value developed in about 0.5 hr in the liver. In the kidney the loss was less severe. Salivary glands lost about 70–80% of their conductivity in 1.5 hr. The losses in muscle conductivity developed late and were not greater than 50%. The drop in conductivity observed in the various organs after circulatory arrest can be accounted for by losses of extracellular electrolytes from the tissues, which could be demonstrated in preparations stained for chloride. In this context the electrolytes in the blood plasma have to be included in the extracellular compartment. The extracellular electrolytes are lost either because they are transported into the intracellular compartment or because they leave the tissue with blood that flows out of the organ after circulatory arrest.
Cerebral high-energy phosphates during insulin hypoglycemia
Authors: Tarr Merrill , Brada Donald , Samson Frederick E.
Published: December 2017

The high-energy phosphate compounds in whole brain from normal and insulin hypoglycemic rats were analyzed with ion-exchange methods. When the rats are severely hypoglycemic but not unconscious, the total concentration of high-energy phosphates in brain is not decreased.
Urea transport in the central nervous system
Authors: Kleeman Charles R. , Davson Hugh , Levin Emanuel
Published: December 2017

The kinetics of urea transport in the central nervous system have been studied in rabbits during sustained intravenous and intracisternal infusions of C12 and C14 urea. The steady state content of urea in the water phase of the white matter and cord was approximately equal to its content in plasma water. However, the water of whole brain and gray matter had levels of urea which exceeded those in plasma by 7 and 18%, respectively, whereas the urea in cerebrospinal fluid (CSF) was only 78% of the plasma level. Its rate of penetration into nervous tissue was approximately one-tenth as rapid as into muscle. The intravenous infusion of urea caused a significant decrease in water content of the brain and cord. It was estimated that urea infused into the subarachnoid space penetrated the central nervous system (CNS) tissues at four to five times the rate of transport from blood to CNS tissues. These studies suggest that intravenous infusions of urea lower CSF pressure by decreasing the volume of the brain and cord. The major barrier to urea penetration into nervous tissue is at the capillary level, and not the plasma membrane of the glial or neuronal cells.
A proposed mechanism for epinephrine potentiation by ganglionic blocking agents
Authors: Hilton James G.
Published: December 2017

The blood pressure responses elicited by the injection of 1.0, 5.0, and 10.0 µg/kg of epinephrine were studied before and after blockade of autonomic nervous activity by either ganglionic blocking agents or by total spinal anesthesia. After blockade, blood pressure levels of 100, 130, and 160 mm Hg were maintained by infusion of epinephrine. The results of these studies showed that the pressor responses elicited were inversely related to the level of the maintained blood pressure and that the maximum attained blood pressures did not change markedly with the various maintained blood pressures. In the series of animals treated with ganglionic blocking agents, the maximum blood pressures were approximately the same before and after blockade but in the total spinal anesthetized animals these pressures were approximately 30 mm Hg lower after blockade. It was postulated from these results that autonomic blockade produces an apparent potentiation of epinephrine pressor response not by sensitization of the reacting structures but by lowering the level of catecholamines available to the receptor sites and shifting the dose-response curve to the left.
Perfusion of the cerebral ventricular system in unanesthetized goats
Authors: Pappenheimer J. R. , Heisey S. R. , Jordan E. F. , Downer J. deC.
Published: December 2017

Techniques have been devised for repeated perfusion of the ventriculocisternal system in chronically prepared, unanesthetized goats. The methods are designed for investigations of a) functional effects of prolonged changes of cerebrospinal fluid (CSF) composition and b) quantitative aspects of CSF formation and exchange of materials between CSF and blood. The present paper provides a technical background for subsequent papers dealing with specific problems. Goats tolerate perfusion rates of 1–3 ml/min at pressures adjustable between –10 and +30 cm H2O. Measurements are made of inflow rates, outflow rates, and concentrations of test materials entering and leaving the system. Composition of normal CSF has been determined and directions are given for preparation of sterile synthetic CSF. Brain weight is about 100 g and choroid plexuses 500 mg. CSF volume is 20–25 ml of which 8–12 ml is in the ventricles. Pressure-volume characteristics are described. Steady-state difference between inflow and outflow rates is a linear function of hydrostatic pressure; the slope is related to hydrodynamic resistance to bulk absorption. Preliminary observations are given to show effects of reduced Ca++ on nervous control of the cardiovascular system.
Electrical responses to limbic and thalamic stimulation in the unrestrained hooded rat
Authors: Birzis Lucy
Published: December 2017

A procedure for implanting cortical and subcortical brain electrodes in young hooded rats is described. In unrestrained rats, cortical activity showed patterns of high voltage slow activity or low voltage fast activity correlated with quiet or alert states, respectively. Typical recruiting responses were elicited by stimulation of the mediodorsal thalamic nucleus. Low intensity stimulation of the limbic system produced an electrical response similar to thalamocortical recruiting, and higher intensity stimulation induced a seizure discharge in the limbic circuit with accompanying behavioral signs of excitement and hypermotility. Neither ongoing electrical activity, nor thresholds or amplitudes of response to stimulation of thalamus or limbic system were observably different after a period of 8 weeks of active growth of the rats.
Metabolism of glucose-U-C14 in perfused rat heart
Authors: Opie Lionel H. , Shipp Joseph C. , Evans John R. , Leboeuf Bernard
Published: December 2017

A closed perfusion system was designed to study C14O2 formation during uptake of glucose-U-C14 by the isolated, beating rat heart. An initial period of 5 min of preperfusion with oxygenated buffer allowed stabilization of the heart before 30 min of perfusion in the closed recirculation system. Oxygenation was adequate as judged by cardiac rate and force, the pattern of glucose metabolism, the rate of glycogenolysis, and the perfusate oxygen content. Glucose uptake increased sharply with increasing perfusate glucose concentrations over the range 1.25– 5 mm glucose, with a lesser rise in the 5–10 mm range and very little rise from 10–40 mm. Glucose oxidation, which accounted for 60% of the glucose uptake at 1.25 mm glucose concentration, reached a maximal rate at 5–10 mm. This maximal rate accounted for only 24% of the glucose uptake at 40 mm, indicating the increasing importance of nonoxidative fates of glucose with increasing glucose uptake. Lactate and net glycogen formation, and incorporation of glucose carbon into glycogen, were least at lowest glucose concentrations and increased irregularly as the glucose concentration rose. Uptake and oxidation of fructose-U-C14 (5 mm) was much less than that of glucose.
Effect of strontium on cardiac contractility and membrane resting potentials
Authors: Nayler W. G. , Emery P. F.
Published: December 2017

Isotonic contractions and transmembrane resting potentials were recorded both before and after the addition of ethylenediaminetetraacetic acid (EDTA) (4 mm final conc.) to toad hearts perfused with Ringer's solution containing either Ca++ or Sr++. After EDTA perfusion the introduction of Ringer's solution containing Sr++ resulted in contracture and a low resting potential (30 – 48 mv); the introduction of Ringer's which contained Ca++ resulted in restoration of normal contractility and transmembrane potentials. These results are discussed according to the hypothesis that Sr++, unlike Ca++, does not maintain the resting membrane potential.
Stop-flow studies on renal handling of lithium ions in the dog
Authors: Homer Louis D. , Solomon Sidney
Published: December 2017

Stop-flow experiments were performed on dogs after serum Li concentrations had been raised to 10–21 mEq/liter with intravenous infusions of Li salts. Li is actively reabsorbed at a distal portion of the nephron close to the site of sodium and potassium reabsorption. Li may cause alkalinization of the urine by inhibiting H+ secretion. Stimulation of K secretion by Li could not be demonstrated. Li may reduce K reabsorption.
Metabolism of palmitate and linoleate in intact dogs
Authors: Nestel P. J. , Bezman A. , Havel R. J.
Published: December 2017

Palmitate-9, 10-H3 and linoleate-1-C14 were infused simultaneously into intact dogs as albumin-bound free fatty acids or as esterified fatty acids in chylomicrons. Linoleate bound to albumin was removed more rapidly from the plasma and was incorporated more extensively into triglycerides of very low density lipoproteins of plasma than palmitate. Both linoleate and palmitate were incorporated more slowly into triglyceride fatty acids of low density and high density lipoproteins than into those of very low density lipoproteins. When chylomicrons obtained separately from dogs fed palmitate-9, 10-H3 with milk fat and linoleate-1-C14 with corn oil were mixed and infused into recipients, the rates of removal from the blood of both triglycerides and phospholipids of the two populations of chylomicrons differed, but this did not seem to depend on their chemical composition. Linoleate derived from chylomicron triglycerides disappeared from hepatic triglycerides and phospholipids more rapidly than palmitate and was incorporated more extensively into plasma lipids. Palmitate and linoleate were incorporated in equivalent amounts into circulating free fatty acids, but more linoleate was found in lipids of adipose tissue.
Aerobic metabolism in anaphylactic reaction in vitro
Authors: Chakravarty Nirmal
Published: December 2017

Anaphylactic histamine release from minced guinea pig lung, suspended in a substrate-free medium, was completely inhibited by lack of oxygen but was unaffected by low oxygen tension reducing the oxygen uptake up to one-third of its normal value. Glucose, pyruvate, α-ketoglutarate, and fumarate did not influence histamine release, while succinate in a relatively low concentration had a stimulant effect; the succinate-induced stimulation appeared to be related to its oxidation in Krebs cycle. Malonate, 40 mm, almost completely blocked anaphylactic histamine release but the inhibition was noncompetitive and could not be reversed by succinate. Fluoroacetate, 50–100 µm, and arsenite, 5–10 µm, caused about 50% inhibition of histamine release, probably by blocking the oxidation of citrate and α-keto acids, respectively. Inhibition with both the agents could be reversed by succinate.
Ventricular distensibility and pressure-volume curve during sympathetic stimulation
Authors: Sonnenblick Edmund H. , Siegel John H. , Sarnoff Stanley J.
Published: December 2017

Experiments with an isovolumically contracting canine left ventricle preparation do not indicate that sympathetic cardiac nerve stimulation induces any alteration in ventricular distensibility. If the heart rate is sufficiently high to produce incomplete ventricular relaxation, sympathetic stimulation, by shortening systole, restores the relaxed pressure-volume relation without any indication, however, that ventricular distensibility is changed.
Development of mechanisms for intestinal absorption of vitamin B12 in growing rats
Authors: Boass Agna , Wilson T. Hastings
Published: December 2017

Intestinal uptake of vitamin B12, with and without gastric intrinsic factor (IF), was studied with isolated tissue from rats at various stages of growth. The intestine from fetal and newborn animals showed extremely high uptake of the vitamin in the absence of IF. This IF-independent B12 uptake fell rapidly with time, approaching adult levels at about 14 days. Stimulation of B12 uptake by IF was detectable in the intestine of newborn rats in spite of the high vitamin uptake in its absence. The per cent stimulation due to added IF increased during the 1st 2 weeks because of drastic reduction of the IF-independent B12 uptake. The development of IF and pepsinogen in the stomach of growing rats was also investigated. The stomach wall of fetal and newborn rats contained less than 1% of the IF found in the adult. After the 1st week the amount increased rapidly, reaching adult levels at weaning. A rapid increase in pepsinogen content did not occur until the 3rd week. As the IF-independent transport system decreased in activity, intrinsic factor appeared in the stomach and the adult mechanism became the predominant system for B12 absorption.
Histochemical and manometric studies of cholinesterases in mammalian kidney tissue
Authors: Marx Gilbert L. , Carter M. Kathleen
Published: December 2017

The localization of cholinesterase in kidney tissue of rat, dog, mouse, rabbit, guinea pig, cat, and human has been attempted using the histochemical technique of Koelle. A cholinesterase is located in the glomeruli of rat, dog and mouse; and an aliesterase (eserine-resistant esterase) is located in the tubules of rat and dog. Other species, rabbit, cat, guinea pig, and human, stain very little for esterases in the parenchyma of the kidney using this technique. Nine of thirteen adrenalectomized rat kidneys stained less for cholinesterase in the glomeruli than normal rat kidneys. With the manometric technique hydrolysis rates for several choline esters, using homogenates of kidneys of most species mentioned, were determined. Very little correlation could be made between rates of hydrolysis of these choline esters and the staining obtained with the Koelle technique.
Testicular and accessory organ depression in immature rats with posterior hypothalamic lesions
Authors: Corbin Alan
Published: December 2017

Twenty-day-old male albino rats were subjected to bilateral lesions of the ventromedial nucleus-mammillary body area. The hypothalamic damage resulted in the following modifications: reduction in body, pituitary, and tests weight, disorganization of tubules, absence or reduction of sperm, and partial atrophy of the seminal vesicles and ventral prostate. The results are interpreted as supporting the concept of posterior hypothalamic participation in the regulation of pituitary gonadotropic activity in the immature male rat.
Ganglionic stimulant action of muscarine
Authors: Gyermek L. , Sigg E. B. , Bindler E.
Published: December 2017

Ganglionic stimulant action of muscarine has been demonstrated on the inferior mesenteric ganglion of the cat. The stimulant effect of muscarine on this ganglion is slow in onset and highly sensitive to atropine, thus differing from "nicotinic" ganglion stimulants such as 1,1-dimethyl-4-phenylpiperazinium iodide. The racemic form of muscarine is less potent than the natural l(+) muscarine and the d(–) form is inactive. Three stereoisomers of muscarine, inactive on the postganglionic parasympathetic receptor sites, were also found to be inactive on the ganglion. The existence of ganglionic receptors functionally similar to postganglionic parasympathetic receptors is proposed.
Role of mesenteric lymphatic system in water absorption from rat intestine in vitro
Authors: Lee J. S.
Published: December 2017

With an in vitro rat jejunal preparation it was found that at low distention pressures the absorption rate of segments without mesentery are about 40% lower than the rate of those with intact mesentery. The decrease of absorption rate in segments with lacteal ducts sectioned near the gut wall was the same as the rate for those completely devoid of mesentery. Section of blood vessels showed no decrease but rather a slight increase in rate. The mesenteric lymphatic ducts during water absorption in vitro and in vivo showed rhythmical contractions with an average frequency of 10/min. The lymphatic ducts of an isolated mesentery may continue to contract and transport water for a few minutes. The lymphatic pressure of the isolated segment is assumed to be an approximate measure of absorbing force. Epinephrine may augment lymphatic contractility and may also elevate lymphatic pressure. These observations suggest that the mesenteric lymphatics may play a significant role in water transport.
Frog gastric mucosae bathed in chloride-free solutions
Authors: Rehm Warren S. , Davis Terry L. , Chandler Colston , Gohmann Edmund , Bashirelahi A.
Published: December 2017

The concept that the Cl– and H+ mechanisms are electrogenic was tested with Cl–-free preparations. With an in vitro chamber method it was found that in the resting mucosa bathed in sulfate the potential difference (p.d.) was about zero, and that histamine produced a negative p.d. (nutrient negative), a decrease in the electrical resistance, and H+ secretion. H+ secretion occurred in the absence of short-circuiting, but short-circuiting increased it. The H+ rate was only a fraction of that in Cl– preparations. Clamping voltage in sulfate preparations at successively higher levels (nutrient positive) increased the H+ rate but not to the level in Cl– solutions. In sulfate preparations thiocyanate on secretory side (10 mm) resulted in a decrease in H+ rate, an increase of p.d. (from –17 to +1), and a decrease in resistance. Changing either the secretory thiocyanate concentration over the range of from 10 to 108 mm or the Cl– concentration from 0 to 108 mm produced relatively small changes in p.d., but marked changes in resistance. Findings explained on basis of electrogenic theory by postulation of a limited cytoplasmic biochemical coupling between Cl– and H+ mechanisms.
Effects of hormone administration on milk production of underfed rats
Authors: Ratner Albert , Meites Joseph
Published: December 2017

Attempts were made to determine whether the reduction in milk output induced by underfeeding could be overcome by administration of hormones. Half-fed female rats were injected daily with one of the following preparations, from the 4th–17th days postpartum: 15 or 25 mg anterior pituitary powder; 1 mg growth hormone; 10 µg thyroxin/100 g body wt.; 0.5 or 1 mg cortisol acetate; 1 mg prolactin; 1 IU oxytocin; and the latter three hormones in combination. None of the hormones significantly increased litter weight gains, although cortisol acetate, prolactin, and oxytocin each produced slight gains during the later part of the lactation period. These results indicate that the decrease in milk production associated with underfeeding is due primarily to nutritional inadequacy and not to reduced endocrine function. It is believed that the suckling stimulus maintains the secretion of the hormones essential for milk production and removal at optimal or near optimal levels, even in the absence of adequate food intake.
Lipid changes in cardiac hypertrophy as measured by silicic acid chromatography
Authors: Nelson G. H. , Bear D. M. , Dotson T. O. , Krause R. F.
Published: December 2017

Cardiac hypertrophy was produced in adult, male albino rats by prolonged exposure to reduced atmospheric pressure. Total lipid extracts of the heart were made and the lipids were separated into seven fractions by silicic acid column chromatography. The purity of each fraction was determined by chemical analysis. Fractions II, IV, and VII were found to contain reasonably pure triglyceride, cholesterol, and phospholipid, respectively. Fractions I, III, V, and VI contained cholesterol ester, free fatty acid, diglyceride, and monoglyceride, respectively, but were contaminated with other lipid material. The hypertrophied hearts showed a reduction in percentage of total lipid but no change in the weight of total lipid per heart. As the heart increased in weight the phospholipid content increased and the weight of cholesterol decreased. These findings confirm previous observations that the phospholipid content of muscles increases with activity.
Influence of photic stimulation and hypothermia on the electromyogram of the developing chick
Authors: Peters Joseph J. , Cusick Charles J. , Vonderahe Alphonse R.
Published: December 2017

As the body temperature of developing chicks between the 18th day of incubation and the 3rd week after hatching was lowered from normal to 16 C, the eye was subjected to photic stimulation and electrical recordings were made from the eye, cerebral lobes, and shank muscles. As body temperature drops photic stimulation modifies the amplitude of muscle potentials by first producing reduction in amplitude (35–25 C), then brief augmentation (20–24 C), then prolonged augmentation (20–16 C), first, with the onset of photic stimulation and later with the cessation of photic stimulation. These effects are most pronounced in chicks between the 20th day of incubation and 1 week after hatching.
Responses of muscles of cat small intestine to autonomic nerve stimulation
Authors: Van Harn Gordon L.
Published: December 2017

The externally recorded slow waves from the cat small intestine originate in the longitudinal muscle layer. In vitro the slow waves are recorded from all layers of the intestine if the segment is not immersed in a saline bath. When the longitudinal layer is removed from one region, the magnitude of the slow-wave potential in the other intestinal layers decreases as the distance from the intact longitudinal muscle layer is increased. An active intestine, in vivo, responds to sympathetic nerve stimulation by a hyperpolarization, cessation of spikes, and inhibition of muscle contraction. During inactivity of the intestine, either vagus or sympathetic nerve stimulation results in a depolarization, initiation of spikes, and muscle contraction. The nature of the response is influenced by the frequency of nerve stimulation and by the level of activity of the intestinal muscle, which is altered by intraluminal pressure changes. The effect of drugs on the response of the intestine to vagal and sympathetic nerve stimulation is such as to indicate that both inhibitory and excitatory nerve fibers are present in each of the autonomic nerves. The duration of the latent period of the response is long and highly variable, and a response requires 50–100 nerve volleys.
Influence of manganese on susceptibility of rats to convulsions
Authors: Hurley Lucille S. , Woolley Dorothy E. , Rosenthal Fred , Timiras Paola S.
Published: December 2017

The relationship of manganese to some aspects of brain function was studied in rats. Electroshock convulsions were produced in the following groups: 1) normal controls, 2) manganese-deficient, not ataxic, 3) manganese-deficient, congenitally ataxic, 4) not manganese-deficient, congenitally ataxic. The threshold for minimal seizures was significantly lower than normal in the two manganese-deficient groups. All manganese-deficient rats also showed alterations in the pattern of a maximal seizure. These data are interpreted to mean that brain excitability or convulsability was increased in manganese-deficient rats regardless of the presence or absence of ataxia, thus suggesting that congenital ataxia and increased convulsability are independent expressions of manganese deficiency. The convulsions and death induced by l-hydrazinophthalazine (hydralazine) in normal rats could be prevented by the prior administration of manganese salts. Cortical electroencephalographic (EEG) recordings indicated that ataxic manganese-deficient animals have a higher average EEG frequency under anesthesia than do controls. These studies suggest that the level of manganese in the body is important in determining the susceptibility of an animal to convulsive states.
Determination of fractional disappearance rate of kidney cholesterol
Authors: Duncan Charles H. , Best Maurice M.
Published: December 2017

Mevalonic acid-2-C14 was injected intraperitoneally into rats, and the incorporation of the C14 into cholesterol of various tissues determined. A disproportionate incorporation into kidney cholesterol was observed, resulting in a specific activity 55 times that of serum cholesterol with which it can exchange. This selective labeling of kidney cholesterol and the essentially identical cholesterol-C14 content found in the two kidneys permitted the determination of the disappearance rate constant of kidney cholesterol without the necessity of considering back exchange of the label. One week after the intraperitoneal injection of mevalonic acid-2-C14 into an additional group of rats the left kidney was removed from each animal and its cholesterol-C14 content determined; from 2 to 6 weeks later the remaining kidney was removed and its cholesterol-C14 content also determined. A disappearance rate constant of the labeled kidney cholesterol of 0.030 day–1 was found.
Analysis of muscular development of mice at high gravity
Authors: Bird John W. C. , Wunder Charles C. , Sandler Naomi , Dodge Christopher H.
Published: December 2017

Although 4 g, as simulated by continual centrifugation, delays growth of the heart, diaphragm, and gastrocnemius muscles, some growth of these organs is possible at this gravitational field. Over-all body growth actually suffers a more marked retardation than do these experimental organs. Results are for both sexes of NLW white mice, whose exposure was initiated at the age of 5 weeks. The fractional water content was almost constant throughout, being only slightly lower in the experimental muscles. Analysis for noncollagen-nitrogen (NCN) was employed as an index of contractile and sarcoplasmic proteins. Throughout the experiment, concentration of NCN was below the control level in the diaphragm tissue. For the heart, the fraction was 26 ± 12% below normal after 2 weeks of centrifugation. However, the NCN concentrations were not measurably changed in the heart after 1, 4, and 8 weeks of centrifugation; moreover, throughout the experiment, there were no measurable changes of NCN concentration for the gastrocnemius muscles. Although muscular growth would be possible in a gravitational field exceeding the terrestrial intensity, some alteration in the type of musculature would be expected.
Plasmatic diatrizoate-I131 disappearance and glomerular filtration in the dog
Authors: Blaufox M. Donald , Sanderson David R. , Tauxe W. Newlon , Wakim Khalil G. , Orvis Alan L. , Owen Charles A.
Published: December 2017

A study was made of the disappearance of sodium diatrizoate-I131 from the plasma of ten dogs after single intravenous injections. The plasma disappearance curves suggested a two-compartment system. The renal plasma clearance of diatrizoate-I131 calculated from these curves and the conventional renal plasma clearance of creatinine were not statistically different. Clearances calculated from the urinary excretion and midperiod plasma concentration of radioactivity in four experiments yielded values averaging 10% less than the creatinine clearance. Chromatographic studies of commercially available diatrizoate-I131 revealed the presence of about 5% free iodide and of about 5% of unidentified impurities. These impurities seem to account, partly at least, for the differences found between diatrizoate clearance and creatinine clearance. Biliary excretion and erythrocytic uptake of diatrizoate were minimal and did not appear to influence the analysis.
Respiration of avian salt-secreting gland in tissue slice experiments
Authors: Borut Arieh , Schmidt-Nielsen Knut
Published: December 2017

Oxygen consumption was determined in tissue slices of the salt gland of the herring gull ( Larus argentatus). The oxygen consumption of slices in a Krebs phosphate medium was 10.0 µl O2/mg tissue dry wt. hr. The addition of metacholine, which simulates the normal parasympathetic stimulation of the gland in vivo, caused an increase in rate of respiration of almost 50%. Doubling the NaCl concentration in the medium inhibited respiration. The presence of metabolic substrates, in particular of succinate, greatly augmented respiration. Lithium ion, which has little effect on tissue respiration in general, stimulated the oxygen consumption of salt gland slices. Potassium, which stimulates respiration in most other tissues, had a pronounced inhibitory effect on salt gland slices. A comparison of the observed oxygen consumption of slices with the calculated energy requirement for sodium transport at rates common in the living bird shows that the in vivo respiration must be much higher than that observed in slices. If the gland in vivo derives the required energy from aerobic respiration it must be characterized by a high rate of oxygen consumption and a very high rate of blood flow.
Hemodynamic mechanisms of increased cardiovascular response resulting from ganglioplegics and atropine
Authors: Page Irvine H. , Olmsted Frederick
Published: December 2017

Continuous measurement of cardiac output and peripheral resistance in unrestrained dogs revealed that constant arterial pressure is maintained by a variable interplay of these factors in accord with the "mosaic theory" of blood pressure regulation. Equipressor responses to several vasoactive agents also depended on this variable interplay. Tetraethylammonium and chlorisondamine had inconstant effects but usually caused an initial decrease in total peripheral resistance and an increase in heart rate. Augmentation of pressor responses by these ganglioplegics was due to larger increases in cardiac output and/or peripheral resistance depending mainly on the primary site of action of the pressor drug. Following tetraethylammonium, norepinephrine caused greater increases in both cardiac output and peripheral resistance; after chlorisondamine, the larger response to norepinephrine depended on a greater peripheral response. Response to serotonin after either ganglioplegic, or after atropine, was largely due to a greater increase in peripheral resistance. Enhanced responsiveness to angiotensin was due to increase in cardiac output or elimination of the normal decrease. Ganglioplegics increased the peripheral response to tyramine, while atropine increased both the cardiac and peripheral response. Response to vasopressin was enhanced by ganglioplegics due to a larger increase in peripheral resistance and a lesser decrease in cardiac output than normally caused by this hormone.
Cooling of rats in carbon dioxide
Authors: Chapin John L. , Edgar John L. R.
Published: December 2017

Rats cool in high carbon dioxide at room temperatures from 12 to 41 C. Confinement plays only a small role in this cooling. The mechanisms for cooling appear to be: 1) lowered metabolic rate, 2) lack of shivering, 3) hyperventilation. High carbon dioxide administration is accompanied by intense peripheral vasoconstriction which, when room temperatures are higher than body temperatures, aids cooling.
Blood volume and intravascular hematocrit in different vascular beds
Authors: Polosa Canio , Hamilton William F.
Published: December 2017

The relative volumes of cells and plasma in the isolated paw, kidney, ileum, and gracilis muscle were determined in 30 dogs by suddenly stopping the flow and washing out the vascular content with saline. Similar experiments were also performed in five dogs on the combined vascular beds draining through the superior and inferior venae cavae. Plasma volume was calculated by dividing the protein content of 1 ml plasma into the total protein recovered; red cell volume was calculated as average concentration of cells in the fluid recovered times its volume. Average blood flows in milliliters per minute per 100 g distended organ weight were 164.5 for the kidney, 26.3 for the ileum, 9.4 for the paw, and 6.4 for the muscle. Average vascular volumes in ml/100 g distended organ weight were 25.9 for the kidney, 8.9 for the ileum, 5.4 for the paw, 4.5 for the muscle, 2.4 for the inferior vena cava bed, and 1.7 for the superior vena cava bed. Average red cell concentrations (as % of the concentrations in the effluent vein during flow) were 69.0 for the kidney, 92.0 for the ileum, 87.0 for the paw, 81.8 for the muscle, 87.0 for the inferior vena cava bed, and 89.0 for the superior vena cava bed.
Metabolism of red and white muscle fiber groups
Authors: Beatty Clarissa H. , Peterson Ruth D. , Bocek Rose M.
Published: December 2017

Rat adductor fiber groups, predominantly composed of either red or white muscle fibers, have been utilized to demonstrate metabolic differences in these two types of voluntary skeletal muscle. Glycogen concentrations of muscle obtained immediately after sacrificing the rats were higher in white than in red muscle, but at the end of 2-hr incubation this relationship was reversed. No difference could be demonstrated in glucose uptake in the two types of muscle, while lactate production was greater in white than in red muscle. Acetoacetic acid uptake by red muscle was higher than that by white muscle as measured by chemical analysis and uptake of acetoacetic acid-C14. A lower percentage of acetoacetic acid-C14 uptake appeared in the lactate fraction in white as compared to red muscle fiber groups. In the case of glycogen, this relationship was reversed and a larger percentage of C14 uptake appeared in the glycogen fraction of white as compared to red muscle. Oxygen uptake and the counts from acetoacetic acid-C14 appearing in C14O2 were higher in red than in white muscle. The creatine phosphate level, after 2-hr incubation, was higher in white muscle. These data demonstrate striking differences in the relative distribution of various metabolic pathways in red and white muscle.
Effect of hypophysectomy on mitotic proliferation in gastric epithelium
Authors: Clark Ray H. , Baker Burton L.
Published: December 2017

Mitotic division of surface mucous cells and of mucous neck cells in the stomach followed a circadian periodicity in rats kept under standardized conditions with exposure to light from 6 am to 6 pm. The greatest activity occurred between 4 am and 10 am and the least at 12 midnight. Circadian periodicity persisted after pituitary excision. Following hypophysectomy, mitotic activity in surface cells was increased during the daytime, with no effect being observed at night. After hypophysectomy mitotic activity of mucous neck cells was depressed at 2 am and 8 am with no change being observed at 12 noon, 2 pm, or 8 pm. When colchicine was given over a 6-hr period during the day to increase the number of countable mitoses, mitotic activity was increased in surface cells and decreased in the mucous neck cells in hypophysectomized rats.