bluuebunny/crossref_metadata_2025 huggingface dataset:
Accuracy of the regulation of caloric ingestion in the rhesus monkey
Authors: McHugh P. R. , Moran T. H.
Published: December 2017

In seven male monkeys, Macaca mulatta, the infusion of nutrients into the stomach just prior to or 20 h before a 4-h feeding period reduced the feeding by an amount comparable to the calories infused. Pure carbohydrates, fat, protein, and mixtures were employed as infusions and given in a random fashion over a caloric range of 75-300 kcal. In a second series of experiments, monkeys were partially fasted on 1 day and in this way deprived of 75, 150, 300, or 450 kcal. On successive days, they overate to compensate for this deprivation. The smaller deprivations (75 and 150 kcal) were corrected on the first recovery day. The 300-kcal deprivation required 2 days to be corrected while the 450-kcal deficit was only partially restored. These experiments demonstrate the capacities of the monkey to respond with precision to caloric supply and deprivation so as to maintain a constant caloric intake.
Glucocorticoid receptors in the guinea pig
Authors: Hodgson A. J. , Funder J. W.
Published: December 2017

In cytoplasmic fractions of liver and kidney prepared from adrenalectomized guinea pigs, tritiated dexamethasone ([3H]DM) is bound with a very low affinity (Kd 4 degrees C greater than or equal to 2 X 10(-7) M). By competition studies, the specificity of this binding was shown to be comparable with that for [3H]DM binding to glucocorticoid receptors in other species. In addition, cytoplasmic preparations from guinea pig liver and kidney appear to inhibit the binding of [3H]DM to rat glucocorticoid receptors under a variety of experimentally determined circumstances. It is proposed that such inhibitory activity may reflect a system of [3H]DM sequestration, perhaps by metabolizing enzymes with a high combining power for glucocorticoids. Both low affinity glucocorticoid receptors and avid binding to sites of metabolism may represent additive cellular bases for the apparent corticoresistance of the guinea pig.
Nycthemeral rhythm in adrenal responsiveness to ACTH
Authors: Dallman M. F. , Engeland W. C. , Rose J. C. , Wilkinson C. W. , Shinsako J. , Siedenburg F.
Published: December 2017

Adrenal adenosine 3',5'-cyclic monophosphate (cAMP) and corticosterone responses to exogenous ACTH were found to be about 2.5 times greater in the evening (at lights off) than in the morning (at lights on) in rats. The rhythm in adrenal responsiveness to ACTH was found to persist in rats treated with dexamethasone 15 and 3 h before exogenous ACTH (in the presumed absence of a rhythm in endogenous ACTH). Treatment with p-chlorophenylalanine did not affect the daily rise in circulating ACTH levels but did abolish the rhythm in adrenal responsiveness to ACTH. The magnitude of the rhythm in adrenal responsiveness to ACTH is greater than the magnitude of the rhythm in ACTH. Because the rhythms are dissociable, we conclude that in vivo measurements of adrenal corticosteroid levels do not necessarily reflect ACTH levels.
Induced hyperthermia in sedated humans and the concept of critical thermal maximum
Authors: Bynum G. D. , Pandolf K. B. , Schuette W. H. , Goldman R. F. , Lees D. E. , Whang-Peng J. , Atkinson E. R. , Bull J. M.
Published: December 2017

The concept of critical thermal maximum (CTM) has been defined in the literature as the minimal high deep-body temperature that is lethal to an animal. In man the CTM has been estimated at 41.6--42.0 degrees C. Data are presented for sedated, unacclimatized, well-hydrated men heated 1 h at esophageal temperatures of 41.6--42.0 degrees C, without sequelae, except for modest elevation of serum enzymes in two of five patients. These data when combined with other observations in the literature suggest that CTM be redefined as the particular combination of exposure time at elevated body temperatures that results in either subclinical (CTM)s) or clinical (CTMc) injuries. Also presented is a mathematical technique, equivalent time at 42 degrees C (Teq 42 degrees), for expressing hyperthermia in terms of body temperature and exposure time.
Body fluid distribution in wild Mus musculus acclimated to water restriction
Authors: Haines H. , McKenna T. M. , Melton J. E.
Published: December 2017

Total body water (TBW), extracellular volume (ECV), and plasma volume (PV) were measured in wild house mice acclimated to chronic water shortage and compared to the same measures in mice exposed acutely to water shortage. Chronic mice were either steady state (SS), i.e., completely acclimated, or nonsteady state (NSS), i.e., transitional. Water shortage was imposed sequentially--1/2, 1/4, and 1/8 ad lib., and no water. SS mice lost solids and cellular fluid at each level of restriction, but maintained plasma volume and partially defended extracellular volume. Acute restriction to 1/2, 1/4, and 1/8 ad lib. caused proportional losses of solids and fluids with the predominant fluid loss being extracellular. Acute restriction to no water caused cellular dehydration plus a loss of extracellular fluids including plasma. Comparison of acute and NSS mice at identical levels of restriction showed the NSS groups to be preacclimated toward further water restriction. Discussion centers on the comparison of acclimated and nonacclimated animals, mechanism of PV defense, and the general process of acclimation.
Diurnal rhythms of bile acid production in the rat
Authors: Duane W. C. , Gilberstadt M. L. , Wiegand D. M.
Published: December 2017

Diurnal rhythms of bile acid synthesis were studied in Sprague-Dawley rats maintained in 12 h of illumination and 12 h of darkness each day. Synthesis, measured as output from a chronic bile fistula, underwent a consistent diurnal change with an amplitude of about 20% around mean daily synthesis and a peak in the dark period. The peak in cholate synthesis preceded the peak in chenodeoxycholate synthesis which preceded the peak in alpha-muricholate synthesis which preceded the peak in beta-muricholate synthesis. Fasting, intravenous infusion of dexamethasone (100 microgram/kg . h), adrenalectomy, and ocular enucleation all failed to abolish the diurnal rhythm in synthesis. In one rat studied 30 days after ocular enucleation the diurnal rhythm in synthesis persisted; however, relative to 4 days after enucleation the phase of the rhythm shifted about 90 degrees suggesting that light deprivation caused the rhythm to become free-running with a period slightly different from 24 h.
Blood oxygen transport and organ weights of two shrew species (S. etruscus and C. russula)
Authors: Bartels H. , Bartels R. , Baumann R. , Fons R. , Jurgens K. D. , Wright P.
Published: December 2017

Blood parameters concerning oxygen transport and relative organ weights of 11 Suncus etruscus and 13 Crocidura russula under light halothane anesthesia were investigated. Mean body weight of S. etruscus was 2.5 g and for C. russula was 9 g, hemoglobin concentration was 17.4 and 15.6 g/100 ml blood, hematocrit was 50 and 44%, red blood cells were 18 and 11 X 10(6)/microliter, respectively. Mean corpuscular volume was calculated to be 26 and 41 micron3, mean diameter 5.5 and 7 micron, and mean thickness 1.2 and 1.1 micron, respectively. Mean corpuscular hemoglobin concentration was in the normal range of mammalian red blood cells. A blood oxygen half-saturation pressure of 35 and 34 Torr at pH 7.4, 37 degrees C and a Bohr factor deltalog P50/deltapH of -0.61 and -0.66 was measured. Experiments with stripped hemoglobin showed that 2,3-diphosphoglycerate is the main oxygen affinity reducing allosteric factor. Relative weights of heart, kidney, and liver are remarkably high in S. etruscus. The maximal oxygen transport of 400 ml . kg-1 . min-1 of S. etruscus is feasible by an enormous heart rate, a large relative stroke volume, a high hemoglobin concentration combined with a low oxygen affinity, and a large Bohr effect.
Mechanism of morphine-induced mydriasis in the cat
Authors: Wallenstein M. C. , Wang S. C.
Published: December 2017

Neurons that increased their firing rate in response to light stimulation were recorded from the pretectal region and the anterior oculomotor nucleus of sedated immobilized cats while morphine (2 mg/kg iv) was administered. The dose produced mydriasis and an increase in spontaneous firing rate of all light-sensitive neurons recorded from the anterior oculomotor nucleus. This suggested that morphine did not produce mydriasis through inhibition of the third nerve. Phenoxybenzamine, iv or topically, antagonized the mydriasis, indicating a peripheral source of sympathetic input as the basis for morphine-induced mydriasis. Morphine (2 mg/kg iv), administered 1 h after adrenalectomy, produced miosis and increased the spontaneous firing rate of light-sensitive neurons recorded from the oculomotor nucleus. These observations suggest that, in the cat, although morphine activates the oculomotor neurons to produce miosis, the effect is masked by the morphine-induced release of catecholamines, mainly from the adrenal glands, which produced mydriasis.
Effects of carotid occlusion and left atrial stretch on supraoptic neurosecretory cells
Authors: Menninger R. P.
Published: December 2017

Acute experiments were performed on pentobarbital-anesthetized cats to determine whether atrial and carotid baroreceptors affected the same neurosecretory neurons in the supraoptic nucleus (SON) of the hypothalamus. The osmosensitivity of these neurons was also determined. Eighty-two SON neurons were antidromically identified and 63 of these increased their firing rates during complete occlusion of the right carotid artery. Further testing of these 63 neurons demonstrated that 56 were inhibited by directly stretching the left atrium and 61 were excited by intracarotid injection of hypertonic saline. Left atrial stretch greatly reduced the neuronal response to carotid occlusion. These results show that the activity of the majority of the antidromically identified SON neurons is altered by left atrial and carotid artery receptors as well as changes in plasma osmolality. Results are consistent with the known influence of these receptors on plasma vasopressin.
Body weight and body composition of male rats following hypothalamic lesions
Authors: Keesey R. E. , Mitchel J. S. , Kemnitz J. W.
Published: December 2017

Carcass analyses were performed on 160 male rats maintaining reduced, normal, or elevated levels of body weight following lateral hypothalamic (LH), sham (control), or ventromedial hypothalamic (VMH) lesions, respectively. Extracted body lipid (ranging from 26 to 738% of the control mean) correlated highly (r = +0.95) with the level of maintained body weight (which ranged from 67 to 191% of control). Neither the nonfat solids (which ranged from 60 to 123% of control) contributed significantly to the variance in body weight (r = +0.01 and +0.06, respectively). Fat thus accounted for approximately 90% of the overall variance in body weight among LH, control, and VMH animals. Consideration of only the LH data, however, revealed a breakdown of this close covariance of body fat and weight. Fat mass correlated significantly with body weight in LH rats maintaining weight 0-12% below normal; but, at maintained body weights below 88%, the correlation between weight and fat in LH rats was only +0.07. Variation in lean body mass then better accounted for differences in body weight. The implications of these observations for existing lipostatic theories of weight regulation are discussed.
Computer simulation of metabolism in pyruvate-perfused rat heart. V. Physiological implications
Authors: Garfinkel D. , Kohn M. C. , Achs M. J.
Published: December 2017

The results of a simulation of metabolism in the pyruvate-perfused rat heart subjected to a sudden increase in work load are interpreted to provide a coherent explanation for the observed physiology. Respiration is most closely correlated with the mitochondrial phosphate potential, calculated from the MgATP and MgADP levels. No correlation between respiration and the pH gradient across the mitochondrial membrane was found. The transient falls in pH in the cytosol and perhaps the mitochondria are due largely to carbonic and lactic acidosis and appear to be only weakly coupled. The heart maintains a high ATP level during the transition to increased work by utilizing its energy reserves in order of decreasing availability in response to physiological signals mediated by Mg2+, Ca2+, and cAMP.
Effect of timing of FICO2 changes on ventilatory period in domestic fowl
Authors: Tallman R. D. , Kunz A. L. , Miller D. A.
Published: December 2017

These experiments were conducted to see if the pacing phenomenon found by Kunz and Miller (Respir. Physiol., 22: 167--177, 1974) in the open-loop, unidirectionally ventilated chicken is important in normally breathing birds. In this study, chickens breathed spontaneously through a tracheostomy from a gas source in which the fraction of CO2 (FICO2) could be rapidly changed. A feedback algorithm kept the FICO2 at 0.05 except for a constant duration pulse (approx 0.6 s) of low FICO2 given tau seconds after the beginning of each inspiration. In all birds tested an increase in tau resulted in a proportional increase of both inspiratory period (TI), expiratory period (TE), and the total period (Ttot). Increases in TI were from 0.5 to 1.0 times the increase in tau. Dynamic expeiments showed TI usually changed on the next breath after a step change in tau, and sinusoidal modulation of tau caused concurrent sinusoidal changes in TI, TE, and Ttot. These findings indicate that the phenomenon that produced pacing in the unidirectionally ventilated birds is important to the ventilatory pattern of normal breathing.
Liver heat production and temperature regulation in the anesthetized dog
Authors: Baconnier P. , Benchetrit G. , Tanche M.
Published: December 2017

Liver heat production (LHP) was measured in the anesthetized dog by a new calorimetric method. Blood flows and temperatures were measured at the same points. The method avoided damage of liver innervation and vascularization. Changes of LHP were investigated under different thermal conditions. Measurements at controlled arterial temperatures within the physiological range showed changes of LHP when arterial temperature was randomly increased or decreased. When measured LHP was compared in experiments carried out at different ambient temperatures, a negative linear correlation was found between LHP and the ambient temperature. It was concluded that liver heat production may be a factor in temperature regulation.
Flux of labeled compounds in biochemical oscillations
Authors: Kaczmarek L. K.
Published: December 2017

If a labeled compound (e.g., a radioisotopically or chemically labeled metabolite) is introduced into any biochemical reaction system, the label will be removed by catabolic reactions and replaced by unlabeled compound through anagolic reactions. It is shown that the removal of labeled compounds is particularly efficient if the rates of the catabolic steps are able to oscillate. This is demonstrated by comparing reaction schemes that maintain the same mean fluxes and concentrations of metabolites and the same overall chemical affinity but which differe in that the rate of catabolism is either constant or oscillates as a function of time. Simple analyses are presented for both small and large oscillations of undefined wave form and for sinusoidal oscillations. The enhanced removal of labeled compounds from oscillating reaction systems is also documented by numerical computation on a nonlinear model system. It is suggested that this ability to remove labeled compounds may have provided a selective advantage for the evolution of some biological oscillations.
Universal eating monitor for continuous recording of solid or liquid consumption in man
Authors: Kissileff H. R. , Klingsberg G. , Van Itallie T. B.
Published: December 2017

A universal eating monitor has been developed that permits covert continuous weighing of a subject's plate or other food reservoir by means of a concealed electronic balance. By coupling the device with a digital computer, it is possible to record precisely the amount consumed every 3 s throughout a single-course meal consisting of a relatively homogeneous mixture of foods. The monitor have been used to compare total intake, meal duration, initial rate of intake, and deceleration of intake in human subjects ingesting either a solid or liquid version of the same food after 3 or 6 h without food. It was found that the liquid form was eaten faster than the solid form, but that total amounts consumed in each form were not significantly different. These results suggest that when the rate of consumption is controlled by the physical consistency of the food, the amount eaten is not determined by the rate of consumption alone. Further studied are necessary to determine the relative roles of visual cues and interoceptive signals on quantity eaten.
Circadian pacemaker times gonadotropin release in free-running female hamsters
Authors: Stetson M. H. , Anderson P. J.
Published: December 2017

Female golden hamsters (Mesocricetus auratus) were housed individually on a photoperiod of LD 6:18 (lights 1000-1600 h). Estrous cyclicity was interrupted for an average of 16 wk after which cycles resumed spontaneously. Such animals are photorefractory, remaining cyclic on normally nonstimulatory photoperiods. Photorefractory females were exposed to continuous darkness in which estrous cyclicity in the population rapidly became asynchronous as each hamster's "day" assumed the endogenous periodicity (tau) of her circadian clock. Tau usually approximated but rarely equaled 24 h. Successive estrous cycles in each animal possessed a periodicity of 4 tau. Preovulatory luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release occurred at a specific time of the animal's circadian day, bearing a discrete phase relationship of 2 to 3 h to the circadian rhythm of locomotor activity. Thus, although seemingly asynchronous with respect to laboratory time, peak preovulatory gonadotropin release on proestrus in free-running hamsters was synchronized with respsect to circadian time. We conclude that a circadian pacemaker times preovulatory gonadotropin release in hamsters.
Polysaccharidic material in chloride cell of teleostean gill: modifications according to salinity
Authors: Pisam M. , Sardet C. , Maetz J.
Published: December 2017

The gill epithelium is known to be implicated in the hydromineral regulation of teleosts, especially owing to its “chloride cells.” We have examined the polysaccharides of chloride cells from euryhaline teleosts adapted to fresh- or saltwater. The use of periodic acid-chromic acid-silver methenamine, colloidal thorium, or radioautography after incorporation of [3H]glucosamine has shown that chloride cells are characterized by a high concentration of polysaccharides in their apical region (at the level of the vesiculotubular system) and by a special polysaccharidic cell coat. The polysaccharide molecules originate from the Golgi area; by 12 h they accumulate within the vesiculotubular system and are released in the apical cavity of the cell within 24 h. In fresh- and saltwater-adapted fish, the localization of polysaccharidic material in chloride cells is basically the same. However, in saltwater-adapted fish, the amount and turnover of the polysaccharide molecules are clearly increased.
PAH transport in rock crab (Cancer irroratus) urinary bladder
Authors: Holliday C. W. , Miller D. S.
Published: December 2017

Crab urinary bladder appears to possess several morphological and functional similarities to vertebrate renal proximal tubule. Sections of intermolt rock crab bladder accumulated PAH by a process that was concentrative (60 min tissue-to-medium ratio (T/M) for 10 microM PAH averaged 24), Na dependent, powered by glycolytic metabolism, and inhibitable by other organic anions. Initial section uptakes exhibited saturation kinetics and a double-reciprocal plot of uptake vs. concentration yielded a single line with a Km of 70 microM and a Vmax of 5 nmol . mg tissue-1 . h-1. Chlorophenol red and bromocresol green (BCG) competitively inhibited PAH uptake. When bladder sheets were mounted in a flux chamber, they exhibited a large, net lumen-to-serosa (L leads to S) flux of 10 microM PAH that was abolished by 1 mM BCG. The small unidirectional S leads to L flux was not BCG-inhibitable. Bladder sheets exhibited PAH T/M greater than 1 after luminal, but not serosal, exposure. BCG only reduced bladder sheet T/M after luminal exposure. The data are consistent with uphill, Na-dependent, and carrier-mediated entry of PAH at the luminal membrane and nonmediated exit at the serosal membrane.
Hepatic modulation of insulin-induced gastric acid secretion and EMG activity in rats
Authors: Granneman J. , Friedman M. I.
Published: December 2017

Intravenous infusions of fructose, a hexose that does not cross the blood-brain barrier, suppressed insulin-induced gastric acid secretion and electromyographic (EMG) activity despite continuing hypoglycemia. Hepatic portal vein infusions of 0.15 M fructose inhibited acid output while the same concentration delivered via the jugular vein did not, suggesting a hepatic site of action of the hexose. Only infusions of fructose that began before onset of the insulin-induced gastric responses were effective, whereas glucose infusions, which elevated plasma glucose levels, readily reversed ongoing gastric activity. The suppressive effects of fructose on gastric activity were prevented by prior section of the hepatic branch of the vagus nerve. In contrast, hepatic vagotomy did not prevent suppression of gastric responses by infusions of glucose, a hexose utilized by both brain and liver. These results suggest that receptors in the brain may initiate and terminate insulin-induced gastric acid secretion and motor activity, whereas sensors in the liver may inhibit these responses.
Irreversible thermodynamics of an isometric twitch, time-dependent general formulation
Authors: Moreno A. H. , Chiu H. H. , Steen J. A. , Reddy R. V.
Published: December 2017

We used the phenomenological laws of irreversible thermodynamics, to derive a system of coupled differential equations describing the time course of the mechanochemical coupling underlying an isometric twitch. Our general description is concerned only with the fundamental process of energy transduction taking place within an idealized unit element of muscle and does not include the description of associated processes such as the excitation-contraction coupling and the mechanical or external coupling that, in bulk muscle, lead to or mediate the fundamental process. The values of the initial conditions and of four parameters are required to solve for the time course of the process. Two of the parameters have a clear physical interpretation and, for the specific case of muscular contraction involving hydrolysis of ATP, their values can be readily estimated from available experimental data. The interpretation of the two other parameters is more speculative, but, from their strong interdependence with the other parameters, their values can be also approximated. Solution of the coupled differential equations yields results consistent with the typical experimental time course of an isometric twitch.
Hematologic response of fish to changes in gas or hydrostatic pressure
Authors: Casillas E. , Smith L. S. , Woodward J. J. , D'Aoust B. G.
Published: December 2017

Hematologic changes were studied in fingering salmon after rapid decompression from combined or independent exposure to gas and hydrostatic pressure. After decompression, fingerling salmon saturated with excess gas under pressure (10.1-40.6 m of seawater) suffered a decrease in thrombocyte counts and fibrinogen, prolonged prothrombin (PT) times, and increased fibrinolytic activity, plasma proteins, and erythrocyte counts in proportion to severity of the dive. After decompression, fingerling salmon exposed to increased pressure experienced an increase in thrombocyte counts and available fibrinogen, shortened PT times, increased erythrocyte counts, and decreased plasma protein levels. It appeared that pressure causes activation of the blood coagulation system of fish. This activation may predispose the fish to increased susceptibility to bubble-induced diffuse intravascular coagulation after rapid decompression. Furthermore, hemoconcentration after decompression may be a pressure-related phenomenon and not a response to bubble-induced anoxia.
Laryngeal reflex inhibition of breathing in piglets: influences of anemia and catecholamine depletion
Authors: Lee J. C. , Downing S. E.
Published: December 2017

Laryngeal reflex inhibition of breathing was studied in 31 piglets of both sexes varying in age from 34 to 93 days. Continuing supramaximal electrical stimulation of one superior laryngeal nerve (SLN) was associated with spontaneous resumption of breathing within 1 min in animals more than 1 mo of age. Respiratory rate and depth were reduced, however. In contrast with normal piglets, electrical stimulation of the SLN in those with severe anemia (Hct = 8.0 +/- 0.5%) caused extended apnea. An intermediate effect was observed in animals with normal hematocrits but given reserpine (2 mg/kg) 2 days prior to study. The apnea response was potentiated in these animals by reduction of the hematocrit from 22.8 +/- 3.4% to 8.4 +/- 1.1% by hemodilution. In normal piglets similar degrees of hemodilution had no discernible effects; An interrelationship between oxygen availability, adrenergic activity, and SLN-induced respiratory depression in young piglets is suggested by these findings.
Circadian periodicity of brain activity and urinary excretion in the epileptic baboon
Authors: Ehlers C. L. , Killam E. K.
Published: December 2017

A 24-H rhythm in the proclivity of the baboon Papio papio to exhibit a seizure response to intermittent light stimulation (ILS) has been uncovered. Seizure response to ILS was found to be greatest in the morning at about 0900 h, 2 h after lights on, and least severe in the evening at about 2000 h 1 h after lights off. Urine cortisol and potassium excretion rhythms followed the same pattern as seizure susceptibility and sodium rhythms were 3 or 4 delayed. Mean values for urine cortisol per 4 h ranged from 25 microgram/4 h at the maxima (0400 to 0800 h) to 2 microgram/4 h at the minima (2000 to 2400 h). Electrolyte rhythms ranged from 13 to 3 meq/4 h for potassium and 1 to 5 meq/4 h for sodium. Changes in electroencephalographic (EEG) activity also accompanied the change in urine cortisol and potassium, and seizure sensitivity, Changes in the EEG at the diurnal minima (2000 h) consisted of a decrease in slow waves concomitant with an increase in fast activity in the 18-25 Hz range,
5-Thio-D-glucose: hypothermic responses in mice
Authors: Francesconi R. , Mager M.
Published: December 2017

Adult male mice were administered several doses of 5-thio-D-glucose (5-TG) at two environmental temperatures, 4 and 22 degrees C. Both intracerebroventricular (icv) and intraperitoneal (ip) administration of 5-TG resulted in significant (P < 0.05 to P < 0.001) decrements in rectal temperature (Tre) that were dose dependent. After 30 min, the hypothermic effects were significantly (P < 0.001, icv, 100 microgram) exacerbated by cold exposure (4 vs. 22 degrees C) and were likewise intensified significantly (P < 0.005, 45 min, fed vs. 18 h fasted) by food deprivation. These reductions in Tre were accompanied by significant (P < 0.001) increases in circulating levels of glucose. The present results indicate that 5-TG may be eliciting both central and peripheral cellular glucopenia concomitant with circulatory hyperglycemia; thus, the resultant hypothermia may be arising from competitive inhibition of glycolysis by 5-TG intermediates as well as reduced availability of tissue glucose.
Thermoregulation in Telazol (CI-744)-anesthetized rhesus monkey (Macaca mulatta)
Authors: Holmes K. R. , Hunter W. S.
Published: December 2017

Seven Telazol (CI-744)-[Telazol is an experimental drug (Parke, Davis) composed of two ingredients in equal amounts by weight: tiletamine HCl, designated chemically as 2-(ethylamino)-2-(2-thienyl)cyclohexanone-HCl, and zolazepam HCl, designated as 4-(o-fluorophenyl)-6,8-dihydro-1,3,8-trimethylpyrazolo-3,4-e 1,4 diazepin-7(IH)-one monohydrochloride] anesthetized rhesus monkeys (Macaca mulatta) were exposed to ambient temperatures (Ta) of 15, 23, 29, 35, and 38 degrees C to evaluate the effect of this dissociative anesthetic agent on thermoregulation. Thermal equilibrium in both anesthetized and control animals at Ta 15 degrees C was through peripheral vasoconstriction and metabolic heat production (M); shivering increased M in the anesthetized group to 1.7 times the resting M of 41.4 W x m-2. Both groups at Ta 38 degrees C regulated body temperature by vasodilation and increased skin evaporative heat loss (Esk) due to sweating. Anesthetized animals increased Esk from 6.4 W x m-2 at Ta 29 degrees C to 32.5 W x m-2 at Ta 38 degrees C. Panting was not observed in either group. Effective tissue thermal conductance was lowest at Ta 15 and 23 degrees C (6.9 and 7.6 W x m2 x degrees C-1, respectively), and increased with Ta's above 23 degrees C (45.0 W x m-2 at Ta 38 degrees C). These results indicate that Telazol-anesthetized monkeys maintain thermal balance at ambient temperatures from 15 to 38 degrees C, and that Telazol induces little or no impairment of thermoregulation in rhesus monkeys.
Central site for pressor action of blood-borne angiotensin in rat
Authors: Fink G. D. , Haywood J. R. , Bryan W. J. , Packwood W. , Brody M. J.
Published: December 2017

A previous study demonstrated that the threshold dose of intra-arterial angiotensin II required to induce a pressor response in the rat was significantly lower when the drug was administered into the carotid artery than when administered into the abdominal aorta. This result was interpreted to indicate that part of the increase in arterial pressure produced by low concentrations of blood-borne angiotensin in this species was the result of an effect on structures in the central nervous system selectively accessible via the carotid vascular bed. The purpose of the present study was to establish more precisely the site of the pressor action of angiotensin within the central nervous system. The central component of the pressor effect of angiotensin was quantified as the difference in pressor responses to intracarotid and intra-aortic infusions of angiotensin II (delta c-a). In conscious rats, delta c-a was attenuated by administration of the angiotensin antagonist, saralasin, into the third cerebral ventricle. In rats with chronic electrolytic lesions of the anteroventral third ventricle (AV3V), delta c-a was abolished. Periventricular structures surrounding the third ventricle appear to mediate the central component of the pressor action of blood-borne angiotensin in the rat.
Disposition of 5-hydroxytryptamine in lungs of developing rats
Authors: Wallace K. B. , Bailie M. D. , Hook J. B. , Roth R. A.
Published: December 2017

The pulmonary vasculature has been implicated in the clearance of several vasoactive peptides, prostaglandins, and biogenic amines from the circulation. In view of the age-related differences in the metabolism of angiotensin by intact lungs, it was of interest to examine the maturation of 5-hydroxytryptamine (5-HT) disposition by isolated perfused lungs. Lungs from newborn and adult rats were perfused with Krebs bicarbonate buffer containing 0.1 microM 5-[14C]HT and samples of the effluent medium collected and analyzed for 5-HT and metabolite. Adult lungs removed and a greater fraction of perfused 5-HT than did lungs from 7-day-old rats. No age-related difference in monoamine oxidase (MAO) activity was observed; however, lung slices from adult rats incubated with 5-[14C]HT accumulated radiolabel at a greater rate than did slices from lungs of 7-day-old rats. The age-related difference in 5-HT clearance by intact lungs may be attributable to a relative deficiency in the facilitated transport process for 5-HT in newborns and may reflect a general functional maturation of processes associated with pulmonary endothelial cell membranes.
Thermoregulatory ability of female rats during pregnancy and lactation
Authors: Knecht E. A. , Toraason M. A. , Wright G. L.
Published: December 2017

Thermoregulatory ability of female rats was examined before pregnancy, during gestation, and during lactation. Thermoregulatory pattern, colonic temperature, evaporative water loss, and survival time were monitored during terminal heating (39.5 +/- 0.9 degrees C) designed to allow prolonged survival (3-4 h) with a sustained thermoregulatory effort. Results confirmed our previously reported observation of decreased thermoregulatory ability in lactating dams, with evidence suggesting thermoregulatory impairment during late gestation. Lactating dams displayed a type III thermoregulatory pattern, and established a rate of evaporative water loss effective for thermostasis at an elevated colonic temperature. However, survival time was significantly decreased compared to nonreproducing females. In contrast, prior heat acclimation tended to increase the survival time of lactating dams. It was concluded that the reduction in thermoregulatory ability observed in lactating dams was related to their inability to maintain a rate of evaporative water loss effective for thermostasis at an elevated colonic temperature.
Effects of amino acids on chloride transport in Aplysia intestine
Authors: Gerencser G. A.
Published: December 2017

This investigation was principally undertaken to examine the mechanism by which organic solutes (amino acids) stimulate chloride transport across the Aplysia californica intestine. Isolated intestine, mounted between identical oxygenated seawater solutions, maintained stable transmural potential differences (serosa negative) and short-circuit currents for several hours at 25 degrees C. The addition of glycine to the mucosal solution stimulated rapid sustained increases in these electrical characteristics. The change in short-circuit increased curvilinearly with increasing concentrations of mucosal glycine. Mucosal glycine stimulated transmural potential difference and short-circuit current after mucosal phlorizin had partially inhibited D-glucose stimulation of the electrical characteristics. Mucosal glycine enhanced the transmural electrical characteristics. Mucosal glycine enhanced the transmural electrical characteristics after serosal ouabain had abolished them. The major portion of the amino acid-induced short-circuit current was carried by a net, active, chloride transfer from mucosa to serosa as determined by flux measurements. These results suggest that the amino acid-induced effect on chloride transport is mediated by a common mucosal membrane carrier for both sodium and the amino acid.
Is angiotensin essential in drinking induced by water deprivation and caval ligation?
Authors: Lee M. C. , Thrasher T. N. , Ramsay D. J.
Published: December 2017

The role of the renin-angiotensin system in drinking induced by water deprivation and caval ligation was assessed by infusion of saralasin into the lateral ventricles of rats. This technique was first validated by demonstrating its capability to specifically antagonize drinking to both systemic and central angiotensin II. However, neither the latency to drink nor the amount of water consumed following 24- or 30-h water deprivation was affected by saralasin. Furthermore, saralasin had no significant effect on the recovery of blood pressure or on the water intake following ligation of the abdominal vena cava. These observations suggest that the renin-angiotensin system alone does not play an essential role in the control of drinking following water deprivation or caval ligation in rats.
Role of arginine vasopressin on fluid and electrolyte balance in rats exposed to high altitude
Authors: Jones R. M. , LaRochelle F. T. , Tenney S. M.
Published: December 2017

Normal rats (N) and rats with hereditary hypothalamic diabetes insipidus (DI) were employed to examine the role of arginine vasopressin (AVP) in the reduction of water intake and urine output during hypoxic exposure. The pattern of reduced water intake followed by recovery was similar in both N and DI rats during 7 days of hypobaric hypoxia (inspired O2 pressure of 75 Torr). Water intake was markedly reduced during the first 6 h of hypoxic exposure in both groups, whereas urine output did not decrease significantly until after 6 h in DI rats and after 18 h in N rats. Total urinary excretion of AVP in N rats decreased and remained depressed during 7 days of hypoxia. (AVP excretion corrected for osmolar clearance was unchanged.) Plasma AVP of conscious N rats was 2.7 +/- 0.40 pg/ml plasma during normoxia and 2.4 +/- 0.74 pg/ml plasma after 2 h of exposure to inspired O2 fractional concentrations of 0.105 (paired samples). We conclude that AVP is not a major factor in the decreased water intake and urine output observed during hypoxia, and that the initial disturbance is a reduced water intake that leads to negative water balance, reduced urine volume, increased urine concentration, and hyperosmotic volume contraction. The reduced or unchanged AVP release in normal rats during hypoxia appears to be inappropriate.
Factors affecting 3H2O transfer capacity of isolated perfused trout gills
Authors: Jackson W. F. , Fromm P. O.
Published: December 2017

Tritiated water (3H2O) transfer capacity (PdA) and vascular impedance (Zg) of isolated trout (Salmo gairdneri) gills perfused with or without epinephrine were studied under conditions of altered osmotic gradients, fluid stirring, perfusion rate (Qa), and efferent pressure (Pe). Transfer capacity was unaffected by osmotic gradients, indicating that 3H2O moves across gills by diffusion and that PdA is independent of hydraulic water movement. Fluid stirring increased PdA asymptotically, suggesting that boundary layers significantly affect diffusion across isolated gills. Transfer capacity was directly related to Qa; Zg was inversely related to Qa. The PdA results can be explained in terms of lamellar recruitment and the distribution of flow between secondary lamellae. Increased Qa reduced Zg due to recruitment and distension of gill vessels. Elevated Pe decreased Zg and PdA. The effects of Pe on Zg resulted from distension of the gill vasculature and increased venous drainage, whereas the effects of Pe on PdA can be explained by changes in the distribution of perfusion between secondary lamellae.
Temperature dependence of rat circadian pacemaker
Authors: Gibbs F. P.
Published: December 2017

Blind female rats were maintained in running-wheel cages in a 12-h light-dark cycle. Hypothermia was induced by ether anesthesia, wetting of the fur by ethanol, and covering with ice. Rats were put in restraining cages and colonic temperatures were maintained between 20 and 32 degrees C for 3-16 h by cooling with ice and water. On recovery from hypothermia, the rats were replaced in their home wheels. Examination of the activity records showed significant phase delays associated with temperatures lower than 28 degrees C. At 20 degrees C, the phase delays indicated that the clock was running at about 64% normal speed giving a mean Q10 of 1.33, which is quite a bit higher than previously reported. It is speculated that, because the rat maintains its body temperature within narrow limits after the neonatal stage, it has lost the precise temperature compensation for the period of its biological clock that has been so well documented in other organisms.
Pre- and postganglionic sympathetic activity in splanchnic nerves of rats
Authors: Celler B. G. , Schramm L. P.
Published: December 2017

Integrated sympathetic activity was recorded on anterior or posterior divisions of the greater splanchnic nerve (GSN) in anesthetized, acutely spinalized, artificially respired Wistar rats before and after ganglionic blockade by hexamethonium. Focal electrical stimulation of spinal sympathoexcitatory pathways elicited large increases in splanchnic sympathetic activity. Ganglionic blockade showed that the anterior and posterior divisions of the GSN are predominantly preganglionic and postganglionic, respectively. Histological examination of excised splanchnic nerves and sympathetic chains indicated that splanchnic postganglionic cell bodies must lie in the chain ganglia rather than within the GSN. Postganglionic responses were calculated for each rat by subtracting responses recorded after ganglionic blockade from responses recorded before ganglionic blockade. As expected, postganglionic responses exhibited longer onset latencies than preganglionic responses. However, evoked activity increased and decreased more rapidly in postganglionic fibers than in preganglionic fibers. Responses to stimulus trains were also better maintained in postganglionic than in preganglionic fibers.
Extracerebral deep-body cold sensitivity in the Pekin duck
Authors: Inomoto T. , Simon E.
Published: December 2017

Pekin ducks, in which cerebral cold sensitivity is negligible, were submitted to general body cooling at warm, thermoneutral, and cold ambient temperature (Ta) with an intestinal thermode. In some animals, hypothermia was enhanced by additional hypothalamic cooling that suppressed cold defense. In other animals, the spinal cord was cooled, either selectively or during intestinal cooling. From core temperature (Tc) and metabolic heat production (M) an overall cold sensitivity of about -5 to -6 W . kg-1 . degrees C-1 was determined at thermoneutrality. Maximum M amounted to four to five times the resting M of 3.8 W . kg-1 and was attained when Tc fell by 2.5 degrees C or more. In the cold, threshold Tc for the activation of M was elevated; overall cold sensitivity remained constant. In the warmth, threshold Tc was lowered; overall cold sensitivity was reduced, if mean skin temperature (Tsk) remained at aout 39 degrees C or higher. Spinal cold sensitivity amounted to about -0.25 W . kg-1 . degrees C-1 at normal Tc and thermoneutral and warm Ta; it increased to aout -0.50 W . kg-1 . degrees C-1 in the cold and during hypothermia. Peripheral cold sensitivity was estimated from Tsk and M as -0.4 to -0.8 W . kg-1 . degrees C-1. It is concluded that overall cold sensitivity in ducks mainly depends on deep-body temperature sensors outside of the central nervous system.
Electroencephalographic serotonin synchronization: area postrema and solitary tract nucleus
Authors: Yamasaki K. , Lico M. C.
Published: December 2017

Unilateral microinjection of serotonin (5-HT) into the solitary tract nucleus (STN) increased the amplitude of all electroencephalographic (EEG) waves ipsilateral to the site of injection. Unilateral STN blockage by lidocaine blocked the ipsilateral effect of 5-HT. Unilateral lesion of the area postrema (AP) increased the amplitude of the ipsilateral EEG in response to 5-HT stimulation of the obex. In contrast, unilateral lesion of both AP and STN decreased the amplitude of the ipsilateral EEG response to 5-HT. The data show that the STN is critically involved in 5-HT synchronizing mechanism and that the AP may have an inhibitory tonic effect on the STN.
Excitation of cardiac sympathetic afferent nerves: effects on renal function
Authors: Meckler R. L. , Macklem L. J. , Weaver L. C.
Published: December 2017

Cardiac sympathetic afferent nerves can reflexly alter renal efferent nerve activity during myocardial ischemia and in response to mechanical or chemical stimulation of cardiac receptors. They also may influence renal excretion of water and electrolytes; however, this potential influence on renal function has not been determined. Therefore, receptors of cardiac sympathetic afferent nerves were chemically stimulated by epicardial application of bradykinin to determine effects on renal function. Experiments were performed in anesthetized dogs in which cervical vagosympathetic trunks were severed and common carotid arteries were tied to diminish influences of arterial baroreceptors and vagal afferent nerves. Chemical stimulation of cardiac afferent neurons excited renal nerve activity and produced decreases in urine flow rate, glomerular filtration rate, and excretion of sodium and potassium. In contrast, no consistent changes in renal function were observed in control dogs, which did not undergo cardiac afferent stimulation. These data provide evidence that activation of cardiac sympathetic afferent neurons can lead to alterations in excretion of water and electrolytes as well as changes in renal nerve activity.
Reflex effects of renal afferents on the heart and kidney
Authors: Kostreva D. R. , Seagard J. L. , Castaner A. , Kampine J. P.
Published: December 2017

The reflex effects of renal afferents on the heart and kidney were studied in dogs anesthetized with pentobarbital sodium. Renal afferent and efferent nerve activity recorded from the renal nerves during occlusion of a single renal vein resulted in increases in nontonically firing renal afferent activity and decreases in tonically firing afferent activity. Renal efferent nerve activity from the contralateral kidney was always inhibited during single renal vein occlusion. This decrease in nerve activity was associated with a decrease in renal vascular resistance. Denervation of the congested kidney eliminated the reflex changes in renal vascular resistance. Cardiopulmonary sympathetic efferent nerve activity from the ansae subclavia was always reflexly inhibited by single renal vein occlusion. Although heart rate and left ventricular contractile force were not altered during renal vein occlusion, right ventricular contractile force decreased by -6 to -25%. This reflex decrease in contractile force was eliminated by denervation of the congested kidney. These studies demonstrate that renal afferents, activated by increases in renal venous pressure, can reflexly inhibit contralateral renal and cardiopulmonary sympathetic efferent nerve activity, decrease contralateral renal vascular resistance, and decrease right ventricular contractile force, without altering heart rate.
Cross-species invariance in state-related motility patterns
Authors: Thoman E. B. , Zeidner L. P. , Denenberg V. H.
Published: December 2017

Each of the sleep and wake states of animals are characterized by specific patterns of behavioral, motoric, and electrophysiological activity. Sleep-wake behavior of rats, rabbits, and human infants (3 of each species) was observed, and, at the same time, a single-channel analog recording was obtained of the motoric activity. A judge who had extensive experience in observing sleep-wake behaviors of human infants, but who was unfamiliar with these behaviors in nonhuman species, scored the analog signals of the rats and rabbits. Another judge, who knew rat and rabbit state behaviors well, but who had not had experience observing human infants, judged the states of the human infants from the analog signals. These judgments were evaluated by comparing them with the findings obtained from direct observation of the subjects. For the nine subjects, the correlations between the judges' scoring of the analog recording and direct observation ranged from 0.856 to 0.985. A more stringent criterion is to determine the exact agreement between judge and observer for each 10-s epoch during the observation. For the major states of active sleep and quiet sleep, the exact agreement ranged from 95.2 to 100%. The wake state was easily judged for rats (100% agreement) but was more difficult for rabbits and humans (59.9 and 66.7%, respectively). This ability to accurately score the state behavior of an unfamiliar species from an analog movement record alone represents a cross-species invariance in neuromotor organization. The critical parameters appear to be regularity or irregularity of respiration and the temporal distribution of gross motor movement.