bluuebunny/crossref_metadata_2025 huggingface dataset:
Apraxia and aphasia for a visual-gestural language
Authors: Poizner H. , Bellugi U. , Iragui V.
Published: December 2017

Since signed languages utilize visual-gestural channels, their study allows a unique opportunity for insight into the ways language and gesture may be represented in the brain. The separability of apraxia and aphasia for sign language was examined in four deaf signers who had unilateral brain damage, three to the left hemisphere and one to the right hemisphere. These patients were administered various tests for apraxia and a test of pantomime recognition. The patient with damage to the right hemisphere was not apraxic as we would expect. For the patients with damage to the left hemisphere, all of whom were aphasic for sign language, strong dissociations emerged between their capacities for sign language and their nonlinguistic motor skills. The language deficits of these patients seemed related to specific linguistic components of sign language rather than to an underlying motor disorder or an underlying disorder in the capacity to express and comprehend symbols of any kind. This separation between linguistic and nonlinguistic function is all the more striking, because sign language and gesture are transmitted in the same modality.
On the genesis of "is" and "ought"
Authors: Iberall A. S.
Published: December 2017

Human beings are confronted by how things, including themselves, work and how they ought to work. Human beings are also confronted, relatedly, by movement and language. The purpose of this note is to suggest an objective physical base within which these philosophic, psychological, and physiological properties of complex systems can be anchored.
A comparative study of potassium-induced relaxation in vascular smooth muscle of tiger salamanders and rats
Authors: Malvin G. M. , Webb R. C.
Published: December 2017

This study compares potassium-induced relaxation in vascular tissue of an amphibian (Ambystoma tigrinum) and a mammal (rat). Aortas (salamanders) and tail arteries (rats) were cut into helical strips for isometric force recording. After norepinephrine-induced contraction in potassium-free solution, arteries relaxed in response to added potassium (1–20 mmol/l). Potassium-induced relaxation was greater in rat tail arteries than in salamander aortas. Half-maximal relaxation occurred at a potassium concentration of approximately 3 mmol/l in both species. Ouabain inhibited potassium-induced relaxation; salamanders were more sensitive to the glycoside than rats. Potassium-induced relaxation decreased as the temperature of the bathing medium was lowered; half-maximal inhibition occurred at 19 and 29 degrees C for salamander aortas and rat tail arteries, respectively. Potassium-induced relaxation also varied with the interval in potassium-free solution, the hydrogen ion concentration (rats only), and the magnitude of norepinephrine-induced contraction. It appears that the cellular mechanism causing potassium-induced relaxation is similar in blood vessels of salamanders and rats. The observations are consistent with the hypothesis that stimulated electrogenic sodium transport produced membrane hyperpolarization and relaxation in vascular smooth muscle.
Role of conjugation and red blood cells for inactivation of circulating catecholamines
Authors: Alexander N. , Yoneda S. , Vlachakis N. D. , Maronde R. F.
Published: December 2017

We investigated the extent of catecholamine (CA) conjugation in plasma and accumulation inside red blood cells (RBCs) after forced immobilization of the rat. A control blood sample was obtained from undisturbed rats resting in home cages via an indwelling aortic catheter. Then rats were immobilized for 2 h, and blood samples were taken during stress at 15 min and 2 h and at 30 min poststress. Both sulfate and glucuronide conjugates were deconjugated by enzymatic hydrolysis and measured by radioenzymatic thin-layer chromatographic methods. In plasma of resting rats, the major conjugate of norepinephrine (NE) is sulfate and that of epinephrine (E) and dopamine (DA) is glucuronide; total conjugates in plasma are 53, 57, and 97% of total NE, E, and DA, respectively. During stress, sulfate conjugates of NE, E, and DA increased significantly along with free NE, E, and DA. DA glucuronide unexpectedly declined at 2 h of stress and 30 min poststress. Concentrations of free CAs rose in RBCs during stress, as did NE sulfate, the only conjugate present in RBC lysate. We conclude that both CA conjugation and RBC accumulation are enhanced when large amounts of free CA enter the circulation as a result of immobilization stress and that the relative importance of these inactivation pathways is different for the three CAs.
Effect of a purified atrial natriuretic factor on rat and rabbit vascular strips and vascular beds
Authors: Garcia R. , Thibault G. , Cantin M. , Genest J.
Published: December 2017

Rat atrium cardiocytes contain a powerful natriuretic and diuretic peptide that has been localized in the specific granules. This atrial natriuretic factor (ANF) produced a potent, dose-dependent relaxant effect on rabbit and rat arterial strips previously made to contract by application of either norepinephrine (NE) or angiotensin II. The effect was not seen if KCl was used as contractile agent or under any conditions with rabbit mesenteric strips. After the application of ANF the vascular strips were refractory to subsequent stimulation by either NE or angiotensin II. The infusion of ANF into a high-resistance isolated perfused rat kidney produced a rapid decrease (33 +/- 5 mmHg) in perfusion pressure that lasted for 18 +/- 3 min. This effect was not seen in the isolated rat mesenteric arterial preparation, even when the perfusion pressure was raised by the infusion of NE. These effects of ANF on vascular smooth muscle are not mediated by prostaglandins, by alpha- and beta-adrenergic and muscarinic receptors, or by an impairment of Ca2+ influx, but they are mimicked by sodium nitroprusside. A low- and a high-molecular-weight ANF produced the same effects. The existence of specific receptive sites for these peptides is suggested.
Gonadal and photoperiodic control of seasonal body weight changes in male voles
Authors: Dark J. , Zucker I.
Published: December 2017

After 15 wk in a short photoperiod (10 h of light/day), adult male voles weighed 25% less and consumed 33% less food than did voles in a long photoperiod (14 h light/day). Neither body weight nor food intake differed among long- and short-day castrated voles. After 19 wk, castrated long-day voles weighed less than did intact animals. Voles reduced their body weight during the first 15 wk in the short photoperiod and increased their body mass during the succeeding 15 wk. Body mass of short-day voles was positively correlated with combined testes weight. Voles in the short photoperiod collected less nesting material than did their long-day counterparts at week 31. Pelage characteristics at week 32 were not affected by castration or by photoperiod. We conclude that the decreased body mass of male voles during the late summer, fall, and early winter reflects a decrease in circulating levels of testicular hormones; gonadal recrudescence and increased circulating androgen levels are in part responsible for the subsequent seasonal increase in body weight. Part of the increased body mass in late winter in field populations or in laboratory voles after 15 wk in the short photoperiod is independent of the resumption of gonadal activity. Fluctuations in neural and endocrine processes, rather than availability of food, are the principal factors underlying seasonal changes in energy balance.
Steady-state autoregulation of renal blood flow: a myogenic model
Authors: Lush D. J. , Fray J. C.
Published: December 2017

This paper presents a model of myogenic control of renal blood flow based on the proposition that steady-state flow occurs when the distending and constricting forces acting on the afferent arteriole are equal. The distending force is represented by the Laplace relationship. The opposing force is governed by the properties of the arterioles and has two components--a purely passive component and an “active” component resulting from vascular smooth muscle contraction. Within the myogenic model, vascular smooth muscle contraction is initiated by “stretch”-induced changes in calcium permeability. Terms are developed describing the effect of stretch on calcium permeability, intracellular calcium, and contractile activity. The model is adapted to describe the myogenic control of blood flow in the dog kidney. Sigmoidal relationships between stretch and calcium permeability and between intracellular calcium and muscle tension seem to account for the shape of the autoregulatory curve. The model predicts a shifting of the autoregulatory pressure-flow curve upward and to the right in response to increased tissue hydrostatic pressure. The model is also exquisitely sensitive to changes in the parameters governing intracellular calcium. These predictions agree well with experimental observations.
Saline acclimation and water and sodium transport across avian small intestine
Authors: Roberts J. R. , Hughes M. R.
Published: December 2017

The uptake of sodium and water across everted sacs of the jejunum and ileum of Pekin ducklings, nestling Glaucous-winged gulls, and adult Japanese quail was measured in both freshwater- and saltwater-acclimated birds to assess the importance of the avian small intestine in salt and water balance after a salt load. The jejunum and ileum together were divided into segments I-V in ducklings and gulls and segments I-IV in Japanese quail. Acclimation to sodium chloride solutions increased the uptake of sodium and water, per unit dry weight of tissue, across segments II and IV in larger ducklings, although no significant differences were observed in smaller ducklings. Sodium and water transport were significantly greater across the posterior region of the small intestine of saltwater-acclimated gulls. In Japanese quail acclimated to sodium chloride solutions, mean values for sodium and water uptake were decreased, compared with fresh-water-acclimated birds, but were not statistically significantly different. Increased uptake of water and sodium after saline acclimation appears to be correlated with the presence of functional salt glands.
Reflex regional vascular responses during passive gastric distension in cats
Authors: Longhurst J. C. , Ibarra J.
Published: December 2017

The increase in systemic vascular resistance during gastric distension in cats may result from variable vasomotor responses in several parallel regional vascular beds. Accordingly, in 23 anesthetized cats the stomach was passively distended with a balloon while systemic hemo-dynamics were monitored. Regional vascular responses were determined during control periods and during gastric distension either by injection of radioactive microspheres (15 cats) or by constant perfusion of vascularly isolated organs (8 cats). During distension, mean arterial pressure and systemic vascular resistance increased by 32 and 28%, respectively. Regional flow measurements indicated no significant alterations in any of the organs examined. Calculated regional vascular resistances indicated vasoconstriction in the kidneys (53%), small intestine (31%), and large intestine (37%) that was reversed by alpha-adrenergic blockade with phentolamine. Constant-flow perfusion studies confirmed the regional vasoconstriction in the renal, superior mesenteric, and hindlimb circulations. These studies suggest a regional heterogeneity of vasomotor response during passive gastric distension in cats that includes no change in vascular resistance in some organs and alpha-adrenergic vasoconstriction in others.
Muscle fiber activity in carp as a function of swimming speed and muscle temperature
Authors: Rome L. C. , Loughna P. T. , Goldspink G.
Published: December 2017

These experiments were performed to determine how ectothermal animals maintain their locomotory ability during acute changes in muscle temperature, despite the large thermal dependence of the mechanical properties of their muscle. The electrical activity of the red (slow-twitch) and white (fast-twitch) muscle fibers of carp was monitored while the carp swam at various speeds at 10 and 20 degrees C. The patterns of recruitment of different fiber types were similar at both temperatures. At low speeds only the red muscle was active, whereas at high speeds the white muscle was active as well. The swimming velocity at which white muscle was initially recruited increased from 26 cm/s at 10 degrees C to 46 cm/s at 20 degrees C. These results suggest that the order of recruitment of motor units was the same at 10 and 20 degrees C but that the recruitment occurred over a narrower range of speeds at the low temperature. Hence, to generate the muscle power required to swim at a certain velocity, fish recruit more muscle fibers, which include faster fiber types when their muscle is cold than when their muscle is warm.
Catecholamine turnover in S 5B/P1 and Osborne-Mendel rats: response to a high-fat diet
Authors: Fisler J. S. , Yoshida T. , Bray G. A.
Published: December 2017

Catecholamine turnover in response to fasting, cold exposure, and a high-fat diet has been measured in the Osborne-Mendel rat, which readily develops obesity when fed a high-fat diet, and the S 5B/P1 rat, which does not. We have tested the hypothesis that this difference in response to diet might be associated with altered rates of norepinephrine or epinephrine turnover. The endogenous norepinephrine concentration in interscapular brown adipose tissue was significantly greater in fasted S 5B/P1 rats than in fasted Osborne-Mendel rats. The fractional norepinephrine turnover rate in interscapular brown adipose tissue of fasted animals was also greater in the S 5B/P1 rat than in the Osborne-Mendel rat. Cold exposure increased the fractional norepinephrine turnover rate in interscapular brown adipose tissue for both strains of rats but increased the fractional norepinephrine turnover rate in the pancreas in only the Osborne-Mendel rats. The turnover of epinephrine and the adrenal concentration of this hormone were not different between the two strains. Normal and high-fat diets were fed to both strains; the Osborne-Mendel rats were pair fed the high-fat diet to prevent excess weight gain. Endogenous concentrations of norepinephrine in interscapular brown adipose tissue was increased by the high-fat diet; the increase was greater in S 5B/P1 rats. The high-fat diet resulted in increased norepinephrine turnover in interscapular brown adipose tissue of the S 5B/P1 rat but not the Osborne-Mendel rat.(ABSTRACT TRUNCATED AT 250 WORDS)
Rat organum vasculosum laminae terminalis in vitro: responses to transmitters
Authors: Sayer R. J. , Hubbard J. I. , Sirett N. E.
Published: December 2017

Spontaneous single-action potentials (units) were recorded extracellularly from explants of the rat organum vasculosum laminae terminalis in vitro. Increasing the osmotic pressure of the bathing solution by 15% by adding NaCl or mannitol increased frequency, whereas reducing the osmotic pressure by 15% by omitting NaCl reduced frequency. The mean frequency ratio (test/control) for 6 (of 13) units responding to a 15% increase was 2.2 +/- 0.5 (SE), and for 8 (of 11) units responding to a 15% decrease it was 0.6 +/- 0.1. These responding units all lay within 55 microns of the ventricular surface. Reduction of the calcium concentration from 2 to 0.75 mmol X l-1 increased the mean frequency of units by 55%. Putative transmitters were added to the bathing solution at 0.1 mol X l-1. The results were as follows: carbamylcholine (26 units), 27% excited and 19% inhibited; luteinizing hormone-releasing hormone (34 units), 38% excited and 12% inhibited; angiotensin II (ANG II) (34 units), 26% excited, and 6% inhibited; somatostatin (14 units), 36% excited and 43% inhibited; serotonin (15 units), 67% excited and none inhibited; and dopamine (13 units), 46% excited and none inhibited. Of the units tested, 86% lay less than 100 microns from the ventricular surface. Units responsive to ANG II lay deeper than units responding to serotonin (P less than 0.005), osmotic changes (P less than 0.001), or carbamylcholine (P less than 0.02).
Analysis of data on efflux of radioactive ions from isolated membrane vesicles
Authors: Grover A. K.
Published: December 2017

Conventional semilogarithmic plots of radioisotope-retained [y(t)], by membrane vesicles during efflux, against time give a gross overestimate of the half-life (t 1/2) of the efflux, if a significant proportion of the radioisotope is retained at equilibrium. By using simulated efflux experiments, it is shown that apparent linearity of such plots evidenced by excellent linear correlation coefficients may not detect such error. 45Ca efflux from sarcolemma of rat myometrium further illustrates this point. Rat myometrium sarcolemmal vesicles were loaded at pH 6.27 and 7.07 with 1 mM CaCl2 and then diluted into solutions containing ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) to result in 1 microM Ca2+ at the above pH values. Analysis using log y(t) vs. t plots gave t 1/2 values of 93.32 +/- 8.64 and 28.63 +/- 1.22 min at pH 7.07 and 6.27, respectively. However, log [y(t) - yeq] vs. t plots yielded t 1/2 values of 28.28 +/- 2.15 and 24.88 +/- 1.00 min. The discrepancy results from a larger equilibrium binding at the higher pH. Therefore it is recommended that the quantity of the isotope retained at equilibrium (yeq) be determined experimentally and then that the data be analyzed using log [y(t) - yeq] vs. t plots to obtain true estimates of t 1/2. This recommendation would be applicable to a wide range of studies.
Caloric intake and Na+-K+-ATPase: differential regulation by alpha 1- and beta-noradrenergic receptors
Authors: Swann A. C.
Published: December 2017

This study examined the effects of diet and treatment with noradrenergic receptor antagonists on weight gain and indices of Na+-K+-adenosine triphosphatase (ATPase) activity in the rat. When rats were fed a palatable cafeteria diet, their caloric consumption increased by about 80%, but they did not gain weight significantly. Ouabain binding and K+-p-nitrophenylphosphatase (NPPase) activity were increased in brown adipose tissue and soleus. These indices remained elevated after the rats were returned to a regular diet. When rats were fasted for 3 days, they lost weight, and the indices of Na+-K+-ATPase activity were markedly reduced in brown adipose tissue and soleus. After refeeding the fasted rats gained weight three times more rapidly than nonfasted rats with similar food intake. Indices of Na+-K+-ATPase activity remained as low as they had been when the rats were fasting. There was a consistent negative correlation between weight gain per calorie eaten and brown adipose tissue NPPase activity. Changes in Na+-K+-ATPase could therefore be involved in the effects of overfeeding and fasting on metabolic efficiency. Desmethylimipramine binding was increased by cafeteria diet and decreased by fasting, consistent with changes in sympathetic nervous system activity. Treatment with prazosin, an alpha 1-noradrenergic receptor antagonist, reduced Na+-K+-ATPase in either control or cafeteria diet-fed rats but did not alter the effect of cafeteria diet feeding. By contrast, treatment with propranolol, a beta-receptor antagonist, prevented the increase in Na+-K+-ATPase during cafeteria diet feeding.(ABSTRACT TRUNCATED AT 250 WORDS)
"Functional polarity" of the spinal cord caused by its longitudinal electric dipole moment
Authors: Athenstaedt H.
Published: December 2017

Specific reactions of the vertebrates that occur through lengthwise application of direct-current (DC) electric fields in the spinal cord and are dependent on the direction of the current (e.g., electric narcosis and electric excitation) can be explained by the existence of a longitudinal dipole moment in the spinal cord. The relationship between "functional polarity of the spinal cord" and its longitudinal dipole moment was established in two different experimental series. 1) Reactions of functional polarity were quantitatively tested on Amphioxus (lancelet) and on numerous Teleostei. On this point the findings of other researchers were confirmed and complemented. 2) Fresh, almost-live spinal cord preparations (cow) were quantitatively tested using pyroelectric (PE) methods. A longitudinal electric dipole moment was demonstrated along the entire length of the white matter. Moreover fresh spinal cord preparations showed a polar orientation on sudden temperature change in a high-voltage DC field. The PE behavior showed a pronounced electric field dependence. Because the white matter is largely composed of longitudinally arranged nerve fibers, individual axons may also have a longitudinal electric dipole moment. Consequently one might expect the following: polar orientation of the growing neurite by an applied DC field, an electric dipole field inside and outside the axon, and a transport of charge carriers along the lines of flux of this dipole field. Moreover PE and piezoelectric (PZE) properties of the neuron should be provable.
Compartmental vs. noncompartmental modeling for two accessible pools
Authors: Cobelli C. , Toffolo G.
Published: December 2017

We examine the limitations of noncompartmental vs. compartmental modeling when two accessible pools are available in kinetic experiments. Focus is on the estimation of mean residence time, whole-body mass, and steady-state equivalent distribution volume. Examples illustrate these points.
Local cerebral glucose utilization in systemic acidosis
Authors: Van Nimmen D. , Weyne J. , Demeester G. , Leusen I.
Published: December 2017

Cerebral glucose metabolism (CMRglu) is decreased during acute and prolonged hypercapnic acidosis and during prolonged metabolic (HCl) acidosis; it is increased in acute (hypocapnic) metabolic acidosis and is not changed in acute isocapnic metabolic acidosis. The alteration in CMRglu can be explained by the changes occurring in intracerebral pH under these experimental conditions. In pontine gray matter, n. tractus solitarii, and n. ambiguus, three structures participating in the neuronal regulation of ventilation, local CMRglu is increased in all acidotic groups, suggesting coupling of function and metabolism at the local level during acidosis-induced hyperventilation.
Differing luminal potential difference of cystic fibrosis and control sweat secretory coils in vitro
Authors: Sato K.
Published: December 2017

Transepithelial potential difference (PD) of isolated segments of the secretory coil of both human control and cystic fibrosis (CF) eccrine sweat glands was measured during stimulation with methacholine (MCh) and isoproterenol (ISO) in vitro. Negative luminal PD of about 10 and 16 mV developed across the secretory coil epithelium in control and CF secretory coil, respectively, during maximal MCh stimulation. ISO (10(-5) M) stimulation generated a mean of 1.9-mV negative luminal PD in control glands; however, ISO failed to enhance the luminal PD beyond the resting level of 0.9 mV in the CF secretory coil. The inhibition of ISO-induced (10(-5) M) luminal PD in control secretory coil by propranolol (5 X 10(-5) M) but not by atropine (10(-5) M) indicated its pharmacologic specificity. The possibility is discussed that this lack of electrical driving force during ISO stimulation could be one of the mechanisms for the absence of sweating response to beta-adrenergic stimulation in CF sweat glands reported recently (8). The mechanism for the higher MCh-induced luminal PD in the CF secretory coil remains to be studied.
Effects of a muramyl dipeptide on the temperature and sleep-wake cycles of the squirrel monkey
Authors: Wexler D. B. , Moore-Ede M. C.
Published: December 2017

The circadian sleep-wake and body temperature cycles of squirrel monkeys were monitored continuously in an environment free of time cues before and after a 50-nmol injection of a synthetic muramyl dipeptide (MDP) either 1 h after wake-up time (subjective day) or just before sleep time (subjective night). At both phases decreases in percent time awake (relative to saline controls) were observed. After administration of MDP early in the subjective day, the animals exhibited alert wakefulness only 47.4% of the daytime, compared with a mean 86.7% of daytime after a saline control injection. The transitional stage was significantly elevated from 6.2 to 28.7% of time after MDP. Nonrapid-eye-movement (REM) sleep was elevated in four of five animals, but in the fifth animal, which had the least consolidated base-line sleep-wake pattern, a small decrease in non-REM sleep was seen. Regression analysis demonstrated a significant (P less than 0.01) relationship between the degree of sleep-wake consolidation and the effect of MDP on non-REM sleep. Normal sleep behaviors and spontaneous arousals were observed. MDP given at the circadian nighttime of two animals resulted in sleep and transitional episodes occupying 84% of the subjective night vs. 73% of time asleep after control injection. Again, these were mostly transitional and non-REM sleep stages, and they persisted 4–5 h into the predicted circadian daytime. REM sleep appeared to be suppressed in the early hours after injection at either time of day.(ABSTRACT TRUNCATED AT 250 WORDS)
Receptor-mediated endocytosis: a model and its implications for experimental analysis
Authors: Gex-Fabry M. , DeLisi C.
Published: December 2017

We present a mathematical model for analyzing, simulating, and quantitating the dynamic and steady-state characteristics of receptor-mediated endocytosis. The basic processes considered by the model are ligand-receptor binding, diffusion of receptors and ligand-receptor complexes in the plane of the membrane toward and away from coated pits, binding of ligand-receptor complexes to coated pit proteins, endocytosis of coated pit contents, degradation of ligand, and recycling of undegraded receptors. The model accounts quantitatively for a wide variety of kinetic data and makes new predictions about steady-state characteristics. We show that for homogeneous receptors the slope of the Scatchard plot is not necessarily constant but can have a positive or negative derivative, depending on the concentration of coated pit proteins and their reactivity. This finding suggests that binding data, which show linear and concave curves, might be explainable be a simple coated pit-related mechanism. Similarly the relationship between the x-intercept and the number of receptors is also affected by kinetic parameters controlling endocytosis. We briefly discuss these results in terms of possible mechanisms for the action of tumor promoters, the large variations in receptor number and affinity in the literature, and methods for quantitative characterization of parameters.
Regulation of metabolic rate in Svalbard and Norwegian reindeer
Authors: Nilssen K. J. , Sundsfjord J. A. , Blix A. S.
Published: December 2017

Food intake, body weight, serum levels of triiodothyronine (T3) and free thyroxine (FT4), and metabolic rate were measured at intervals in Svalbard (SR) and Norwegian (NR) reindeer. From summer to winter food intake decreased 57 (SR) and 55% (NR), while body weight decreased 8.6 (SR) and 3.8% (NR). In SR T3 and FT4 changed seasonally, whereas this was only evident for T3 in NR. Resting (standing) metabolic rate (RMR) in winter was 1.55 (SR) and 2.05 W X kg-1 (NR), lower critical temperature (TLC) being -50 (SR) and -30 degrees C (NR). RMR in summer was 2.15 (SR) and 2.95 W X kg-1 (NR), TLC being -15 (SR) and 0 degrees C (NR). Seasonal changes in T3 and FT4 did not coincide with changes in food intake or RMR in either SR or NR. RMR did, however, correlate with food intake. This indicates that seasonal changes in RMR are due to the thermic effects of feeding and represent no physiological adaptation aimed at conservation of energy during winter.
Chemoreceptor and baroreceptor inputs to ventrolateral medullary neurons
Authors: Caverson M. M. , Ciriello J. , Calaresu F. R.
Published: December 2017

Recording experiments were done in chloralose-anesthetized, paralyzed, and artificially ventilated cats to identify single units in the ventrolateral medulla (VLM) projecting directly to the region of the intermediolateral nucleus of the spinal cord (T2) and responding to selective activation of peripheral chemoreceptors (sodium cyanide, 20-60 micrograms in 0.1-0.3 ml saline into medial thyroid artery) and baroreceptors (phenylephrine, 2 micrograms/kg iv). The firing frequency of 49 of the 81 antidromically identified single units was altered by activation of the peripheral cardiovascular receptors. Of these responsive units, 25 responded only to activation of chemoreceptors (17 excited and 8 inhibited), 20 responded in various combinations to activation of both chemo- and baroreceptors, and 4 responded only to activation of baroreceptors. In addition, units that altered their firing frequency during baroreceptor activation (n = 24) responded in the opposite direction to baroreceptor unloading (carotid arterial occlusion). These results suggest that neurons in the VLM are components of bulbospinal sympathoexcitatory and -inhibitory pathways that receive cardiovascular afferent information and in turn influence vasoconstrictor and cardioacceleratory neurons in the intermediolateral nucleus of the upper thoracic cord.
Should blood transport kinetics be modeled in metabolic processes?
Authors: Belforte G. , Bona B. , Molino G.
Published: December 2017

We analyze the interaction between blood transport phenomena and uptake processes when drug kinetics are studied with compartmental models. Relevant advantages in the physiological interpretation of the model parameters are obtained when blood transport is explicitly included in the model. This is done by aggregating into a single compartment all the blood spaces where no exchange with extravascular spaces takes place and separating into different blood compartments those spaces where some uptake and/or return occurs. The proposed strategy extensively uses all available a priori information about the physiological system, instead of considering only the information available in the measurements. This modeling approach has three main advantages: it provides greater insight into the identified quantities; it allows the introduction of quantitative a priori information; and it facilitates the experiment design task.
Motor activity in decerebrate rats: spontaneous and nutrient-induced changes
Authors: Junquera J. , Lanzagorta-Sanchez G. , Mejia-Perez B. E. , Racotta R.
Published: December 2017

Bilateral decerebration was performed in adult Wistar rats of either sex under pentobarbital sodium anesthesia. Decerebrate rats were aphagic and adipsic and received 44 kcal/day subcutaneously by gastric intubation. Their motor activity was recorded in the morning after an 18-h fast, following various treatments: 10 ml mash (22 kcal) or 3.6 g glucose/kg; intragastric, intraperitoneal, or subcutaneous injection of glucose (3.6 g/kg) or glycerol (1.84 g/kg); or injection of epinephrine (25 micrograms/kg ip or im). These treatments were also applied to control rats previously maintained in the same conditions. Motor activity of both operated and control rats was generally reduced in a similar manner: intragastric mash greater than intraperitoneal glucose = intraperitoneal glycerol greater than or equal to intragastric glucose greater than intraperitoneal epinephrine. Subcutaneous glucose and glycerol and intramuscular epinephrine produced hyperactivity, at least for the first 30 min. Thus decerebrate rats respond like normal rats by reducing their general activity when subjected to the same satiating treatments given intragastrically or intraperitoneally. This suggests that the brain stem of rats can monitor peripheral information regarding caloric replenishment.
Properties of renobulbar afferent fibers in rats
Authors: Knuepfer M. M. , Schramm L. P.
Published: December 2017

Myelinated renobulbar sensory fibers project directly from the kidney to the dorsomedial medulla. They can be activated by punctate stimulation of the kidney. In these experiments we studied the physiological modality and the intrarenal locations of the receptors for renobulbar fibers. Renobulbar fibers were identified in recordings from the renal nerves of anesthetized rats. Although nonmyelinated renal afferent fibers were activated by increased intrarenal pressure and by chemical stimuli, no renobulbar fiber activated by punctate mechanical stimulation was activated by these other stimuli. Occasionally single fibers could be activated by punctate stimulation of two or more sites on the surface of the kidney, and responses from each site could be selectively blocked with a local anesthetic. Renobulbar fibers could be activated by electrical stimulation of discrete regions deep within the renal parenchyma. Increased intrarenal pressure increased the sensitivity of receptors to punctate stimulation but not to electrical stimulation of the kidney. We conclude that myelinated renal afferent fibers in the rat respond to external mechanical stimuli, lie deep within the renal parenchyma, and occasionally have more than one receptor.
Effect of stimulation of nucleus raphe dorsalis on carotid blood flow. I. The monkey
Authors: Goadsby P. J. , Piper R. D. , Lambert G. A. , Lance J. W.
Published: December 2017

The dorsal raphe nucleus (DRN) and surrounding midbrain of 16 anaesthetized monkeys were stimulated electrically, and carotid blood flows were measured with electromagnetic flow probes. Stimulation of the DRN caused a frequency-dependent decrease (vasodilatation) in both internal and external carotid vascular resistance, which was abolished in both circulations by bilateral section of the facial nerve intracranially. These vasodilator responses were unaltered by intravenous administration of muscarinic cholinergic or by alpha- or beta-adrenoceptor antagonists. A postdilatation constrictor response, observed in the external carotid circulation, was blocked by the alpha-adrenoceptor antagonist phentolamine. It is concluded that projections of the DRN through the greater superficial petrosal branch of the facial nerve mediate vasodilatation in both internal and external carotid circulations.
Changes in anatomy, glomerular filtration, and solute excretion in aging rat kidney
Authors: Corman B. , Pratz J. , Poujeol P.
Published: December 2017

Changes in kidney function were studied in anesthetized female WAG/Rij rats 6, 18, and 30 mo old. The growth in kidney size measured between 6 and 18 mo and 18 and 30 mo was due to enlargement of the glomeruli and lengthening of the proximal tubules, without significant changes in the number of nephrons. Glomerular filtration per gram kidney was unaffected between 6 and 18 mo but diminished 27% between 18 and 30 mo. This reduction was accompanied by an intrarenal redistribution of individual filtration rates for the superficial and deep nephrons. Fractional excretion of sodium, potassium, calcium, and magnesium declined sharply between 6 and 18 mo but did not change further between 18 and 30 mo, whereas the fractional excretion of amino acids and glucose remained constant between 6 and 18 mo but rose in the 30-mo group. Taken together, these observations indicate that, in the rat, kidney aging cannot be reduced to a loss in the number of functional nephrons but is the result of several differential and specific processes.
Electrophysiological and morphological characterization of neurons in stellate ganglion of cats
Authors: Bosnjak Z. J. , Kampine J. P.
Published: December 2017

We have studied the general morphology of cat stellate ganglion cells in relation to the synaptic input that each neuron receives. Horseradish peroxidase (HRP) was injected intracellularly into single neurons of the isolated cat stellate ganglia. Neurons of the stellate ganglion receive synaptic information from central and peripheral nerves. Electrical stimulation of the preganglionic nerves (T3 ramus), and postganglionic stimulation of the ventral or dorsal ansa subclavia, evoked graded excitatory responses that led to the discharge of one or more action potentials. The neurons receiving synaptic input from preganglionic and postganglionic nerves have a complex dendritic morphology. These neurons were located close to the postganglionic nerves and had an axon emerging from these nerves. Other neurons located closer to the preganglionic nerves had no identifiable axons leaving the ganglion and could not be excited antidromically by electrical stimulation. These neurons appear to be interneurons. These results indicate that neurons of the cat stellate ganglion are organized in a complex fashion that could be important in the integrative properties of these neurons.
Electrolyte transport by alkaline gland of little skate Raja erinacea
Authors: Smith P. L.
Published: December 2017

Transepithelial flux studies and conventional intracellular microelectrode measurements were employed to examine the mechanisms of ion transport by the alkaline gland of the male skate, Raja erinacea. These studies reveal that the transepithelial potential is 6.9 +/- 0.6 mV, lumen reference, and that the transepithelial resistance is 140 omega . cm2. The short-circuit current across this epithelium is entirely accounted for by net secretion of Cl, whereas transepithelial active transport of Na does not appear to be present in this tissue. Cl secretion and/or short-circuit current are reduced by serosal furosemide and abolished when the bathing solution Na is replaced with choline or when ouabain is added to the serosal bathing solution. Intracellular microelectrode studies reveal that the apical membrane potential is -43 mV, cell interior negative to the mucosal bathing solution. The transepithelial resistance in these tissues was 103 +/- 12 omega . cm2 and the apparent fractional resistance, i.e., the ratio of the change in apical membrane potential to the change in transepithelial potential produced by passing current across the epithelium was 0.39 +/- 0.09. Ion substitution experiments demonstrated that the apical membrane is dominated by a large Cl conductance while the basolateral membrane contains a barium-sensitive potassium conductance. These results suggest that the mechanism of Cl secretion by the alkaline gland is similar to the mechanism described for a variety of Cl secretory epithelia.
Is gastric sham feeding really sham feeding?
Authors: Sclafani A. , Nissenbaum J. W.
Published: December 2017

Rats were fitted with gastric cannulas, food deprived, and allowed to drink a sugar solution that drained out of the opened cannula; i.e., the rats sham-fed. Although this procedure is thought to prevent absorption of ingested food, it was found that the sham feeding of a 32% glucose or sucrose solution significantly elevated blood glucose levels. The addition of acarbose, a drug that inhibits the digestion of sucrose, to the 32% sucrose solution blocked the blood glucose rise, as did closing the pylorus with an inflatable pyloric cuff. Neither the drug nor the cuff, however, reduced the amount of sucrose solution consumed. These findings indicate that gastric sham feeding does not necessarily prevent the digestion and absorption of food, although absorption is not essential for the appearance of a vigorous sham-feeding response. Nevertheless the possibility that neural or hormonal feedback from the stomach contributes to the sham-feeding response cannot be excluded, and until this issue is resolved the results of gastric sham-feeding studies should be interpreted with caution.
Effect of propylthiouracil dose on serum thyroxine, growth, and weaning in young rats
Authors: Blake H. H. , Henning S. J.
Published: December 2017

The antithyroid drug propylthiouracil (PTU) is a potent inducer of hypothyroidism in the rat. To evaluate the effects of PTU on serum thyroxine (T4) concentration, growth, and weaning progression during development, five doses of PTU (0.0001, 0.0005, 0.001, 0.005, and 0.01 g/100 ml) were administered to infant rats via drinking water of the dam. The highest dose, 0.01%, is commonly used in developmental studies. The results indicate that 0.001% PTU creates hypothyroid pups without the debilitating characteristics of pups raised on 0.01% PTU. A second experiment examined the effects of 0.001% PTU on serum T4 concentration, growth, and weaning progression during the fourth postnatal week. Serum T4 concentration was depressed throughout the study period to 25% of controls. The hypothyroid pups continued to grow, although they were significantly smaller than untreated controls. Weaning was initiated by postnatal day 22 and completed on day 29. For normal untreated pups, weaning is initiated by day 17 and completed by day 26. Thus hypothyroidism delays but does not abolish the weaning process.
Reflex control of osmotically stimulated vasopressin in normal humans
Authors: Goldsmith S. R. , Cowley A. W. , Francis G. S. , Cohn J. N.
Published: December 2017

Previous studies have shown that in normal humans plasma arginine vasopressin (AVP) does not increase in response to unloading of cardiopulmonary and sinoaortic baroreceptors produced by lower body negative pressure (LBNP) unless hypotension occurs. To assess whether prior osmotic stimulation of AVP might bring out latent sensitivity to nonosmotic control mechanisms in humans we studied the response of plasma AVP to graded LBNP after a 105-min infusion of 5% saline in a group of eight normal individuals. During the infusion and before LBNP, serum osmolality increased from 288 +/- 9 to 300 +/- 10 mosmol/kg, and plasma AVP increased from 4.4 +/- 1.7 to 8.0 +/- 2.5 pg/ml. Neither osmolality nor AVP changed significantly during two stages of LBNP that first reduced central venous pressure alone and then reduced central venous pressure with accompanying tachycardia and narrowing of the pulse pressure. Time control studies performed in five individuals subjected to central venous catheterization and an identical hypertonic saline infusion failed to show significant spontaneous changes in AVP during a comparable interval after the infusions but without LBNP. Thus osmotic stimulation with hypertonic saline did not render AVP more sensitive to nonhypotensive unloading of cardiopulmonary and sinoaortic baroreceptors in normal humans.
Fluctuations in basal plasma levels of pancreatic polypeptide in monkeys and humans
Authors: Hansen B. C. , Jen K. L. , Pek S. B. , Wolfe R. A.
Published: December 2017

We reported that significant rapid oscillations occur in basal plasma levels of insulin, glucagon, and glucose in rhesus monkeys and humans. We searched for evidence for similar spontaneous fluctuations also in plasma levels of pancreatic polypeptide (PP). Mean +/- SE basal plasma levels of PP were 236 +/- 15 pg/ml in 11 monkeys, 64 +/- 12 in nine normal-weight human subjects, and 74 +/- 10 in nine obese human subjects. 1) PP levels fluctuated with periods of 6–26 min. The fluctuations in PP were less regular than and did not temporally correlate with the fluctuations in plasma levels of insulin, glucagon, or glucose (usual periods 8–12 min). 2) In human subjects the concentration but not the periodicity of PP was related to obesity. 3) Comparisons of simultaneously determined levels of PP in portal and central venous plasma of monkeys suggested that PP may be extracted to varying degrees by the liver, even under basal well-controlled conditions, and that neither the size of the PP portal-central gradient nor the period and amplitude of fluctuations was associated with PP concentration. We conclude that plasma PP levels fluctuate with such a large amplitude that these fluctuations must be considered in the interpretation of experimental results based on limited numbers of samples.
Renal responses to hypoxemia during renin-angiotensin system inhibition in fetal lambs
Authors: Nakamura K. T. , Ayres N. A. , Gomez R. A. , Robillard J. E.
Published: December 2017

The role of the renin-angiotensin system (RAS) in modulating the renal hemodynamic and functional responses to hypoxemia was studied in chronically catheterized fetal lambs (132-143 days gestation; term 145 days) before and during administration of either captopril or [Sar1-Gly8]ANG II. Base-line mean arterial blood pressure decreased significantly after administration of either captopril or [Sar1-Gly8]ANG II. This decrease was associated with a significant decline in renal vascular resistance (RVR) in captopril-treated fetuses, whereas no changes in RVR were observed in [Sar1-Gly8]ANG II-treated fetuses. However, the decline in renal blood flow (RBF) and the rise in RVR associated with hypoxemia in control fetuses were not attenuated significantly during inhibition of the RAS using either captopril or [Sar1-Gly8]ANG II. Moreover neither captopril nor [Sar1-Gly8]ANG II blunted the hypertensive response associated with fetal hypoxemia. The renal functional response to captopril was different from the response observed during infusion of [Sar1-Gly8]ANG II. Administration of [Sar1-Gly8]ANG II produced significant decreases in urinary flow rate (UFR), glomerular filtration rate (GFR), and urinary electrolyte (Na+, K+, Cl-) excretion rates, whereas no changes were observed during captopril infusion. The effects of hypoxemia on renal function were not modified after captopril. However, [Sar1-Gly8]ANG II tended to increase UFR and GFR, but these changes were pressure-dependent and not directly related to inhibition of the RAS. This study suggests that the RAS is not an important mediator of the fetal renal hemodynamic and functional responses to hypoxemia.
Effects of adrenalectomy on energy balance of obese mice are diet dependent
Authors: Smith C. K. , Romsos D. R.
Published: December 2017

Obese (ob/ob) and lean mice were adrenalectomized at 3 or 6 wk of age and fed a high-carbohydrate stock diet or a high-fat semipurified diet for 3 wk. Adrenalectomy of obese mice fed the stock diet reduced the energy intake, energy gain, and efficiency of energy retention so that the values equaled those of lean mice. Hindlimb muscle gain of adrenalectomized obese mice fed the stock diet increased by 50-100%, and concentrations of plasma insulin were reduced so that they also approached values in lean mice. In contrast to results obtained when the stock diet was fed, adrenalectomy of obese mice fed the high-fat diet resulted in only slight reductions in energy intake, energy gain, or efficiency of energy retention. Likewise, muscle gain was not improved nor were plasma insulin concentrations decreased when adrenalectomized obese mice were fed the high-fat diet. Although adrenal secretions contribute substantially to the gross obesity that develops in ob/ob mice fed the stock diet, these secretions are unnecessary for development of obesity in ob/ob mice fed the high-fat diet. Factors other than adrenal secretions per se, which are influenced by diet composition, thus mediate development of obesity in ob/ob mice.