bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuropeptide Y in the hypothalamus: effect on corticosterone and single-unit activity
Authors: Albers H. E. , Ottenweller J. E. , Liou S. Y. , Lumpkin M. D. , Anderson E. R.
Published: December 2017

The purpose of the present study was to determine whether neuropeptide Y (NPY) acts within the hypothalamic paraventricular nucleus (PVN) or the suprachiasmatic nucleus (SCN) to alter circulating levels of corticosterone and to evaluate the effects of NPY on the single-unit response of PVN and SCN neurons using the hypothalamic slice preparation. Blood levels of corticosterone were determined in groups of rats that received microinjections of NPY or saline (Sal) into the PVN or SCN. NPY injected into the PVN 4 h after light onset resulted in corticosterone levels of 13.15 +/- 2.18 (SE) micrograms/dl within 1 h, which were significantly higher than the corticosterone levels of 4.08 +/- 1.78 micrograms/dl seen in rats receiving Sal injections. In contrast, no significant differences were observed in circulating levels of corticosterone between groups of rats 1 or 4 h after NPY or Sal microinjection into the SCN. In the hypothalamic slice, NPY was found to produce primarily inhibitory responses in both SCN and PVN neurons. Forty-nine percent of the SCN units examined were inhibited. In addition, another 20% of the neurons tested in the SCN displayed excitation followed by more sustained inhibition. In the PVN, 45% of the units examined were inhibited by NPY, however, nearly 30% of the remaining neurons were significantly excited by NPY. In summary, NPY alters the electrical activity of both SCN and PVN neurons but appears to act only within the PVN to influence circulating levels of corticosterone. These and other data indicate that NPY acts as an important neurochemical messenger within several hypothalamic sites.
Regulation of the level of uncoupling protein in brown adipose tissue by insulin
Authors: Geloen A. , Trayhurn P.
Published: December 2017

The role of insulin in the regulation of the thermogenic activity and capacity (uncoupling protein content) of brown adipose tissue (BAT) has been investigated using mice made diabetic with streptozotocin and then subsequently infused with different doses of insulin. After 12 days of diabetes, the animals received either 0, 8, 16, or 32 units of insulin.kg body wt-1.day-1 delivered by osmotic minipumps implanted subcutaneously for 12 days. After 12 days of diabetes, body weight, interscapular BAT, and epididymal white adipose tissue weights were each reduced. In BAT, significant decreases (P less than 0.05) in the mitochondrial protein content (63%), cytochrome oxidase activity (79%), mitochondrial GDP binding (51%), and the specific mitochondrial concentration and total tissue content of uncoupling protein (71 and 89%, respectively) were obtained, indicating that the thermogenic activity and capacity of the tissue were reduced in diabetes. The infusion of insulin at a dose of 8 units.kg-1.day-1 normalized mitochondrial GDP binding and doubled the concentration of uncoupling protein. Body weight, epididymal white adipose tissue weight, and the mitochondrial protein content of BAT were restored with 16 units of insulin.kg-1.day-1. Higher doses of insulin did not further increase the specific mitochondrial concentration of uncoupling protein, but the mitochondrial content (and thereby the total uncoupling protein content) of BAT was increased and blood glucose normalized. There was a significant correlation between the dose of insulin replacement and several of the parameters measured in BAT: mitochondrial protein content (r = 0.68, P less than 0.001), cytochrome oxidase activity (r = 0.54, P less than 0.001), and total uncoupling protein content (r = 0.68, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Renin-angiotensin system and opioids during acute hemorrhage in conscious rabbits
Authors: Schadt J. C. , Gaddis R. R.
Published: December 2017

We measured changes in plasma renin activity (PRA) and used angiotensin-converting enzyme blockade with captopril to evaluate the role of the renin-angiotensin system during hemorrhage and after opioid receptor blockade in conscious rabbits. The increase in PRA after nonhypotensive hemorrhage was not statistically significant. PRA increased sixfold after a hypotensive hemorrhage to a mean arterial pressure less than 40 mmHg. This increase was statistically significant. Captopril altered the hemodynamic response to hemorrhage. The normal increase in vascular resistance early in hemorrhage was reduced by captopril pretreatment. After a critical blood loss, arterial pressure and heart rate decreased in both groups. The blood loss required to decrease mean arterial pressure to less than 40 mmHg was approximately 25% less in animals pretreated with captopril. The characteristic decrease in vascular resistance coincident with the onset of hypotension was still present after captopril pretreatment. Injection of naloxone or saline during acute hemorrhagic hypotension did not affect PRA. However, recovery of blood pressure after naloxone or saline was attenuated by converting-enzyme blockade. This attenuation was due primarily to a reduction in spontaneous recovery (i.e., recovery after the control saline injection) and not to a reduction in the response to naloxone. We tested whether this effect of captopril might be due to an interaction of ANG II and catecholamines. The plasma norepinephrine (NE) response to naloxone was statistically similar with and without captopril. In contrast, the response to exogenous NE after hypotensive hemorrhage was significantly reduced by captopril pretreatment. Captopril apparently did not alter baroreflex sensitivity but did reset the baroreflex to lower pressure levels during naloxone's pressor response.(ABSTRACT TRUNCATED AT 250 WORDS)
Facial vessels of desert camel (Camelus dromedarius): role in brain cooling
Authors: Elkhawad A. O. , Al-Zaid N. S. , Bou-Resli M. N.
Published: December 2017

The reactivity of the superficial veins of the camel was investigated in vitro in response to stretch, heat, norepinephrine, and transmural nerve stimulation (TNS). Stretch at 30 degrees C or 37 degrees C produced a maintained tone and phasic contractions of the facial and nasal veins. The developed tone increased significantly with increasing the temperature (from 30 to 45 degrees C), especially in the proximal part of the buccal facial vein. Norepinephrine caused a constrictor response in the facial vein with the proximal part showing a lower maximum. TNS evoked a constrictor response in proximal segment and a dilator response in the more proximal segment of the buccal facial vein. Either responses were blocked by bretylium or tetrodotoxin. Morphological examination of the vasoactive segment of the facial vein showed a thick muscular layer and a valve in the proximal segment of the buccal facial vein. These results show functional variation in the distribution of adrenoceptors in the facial vein. The high-temperature sensitivity of the buccal facial vein suggests that this part could serve as a temperature-sensitive sphincter that diverts cool nasal blood to the brain for selective cooling of the camel brain during heat stress.
Chemospecific deficits in taste detection after selective gustatory deafferentation in rats
Authors: Spector A. C. , Schwartz G. J. , Grill H. J.
Published: December 2017

Electrophysiological data support the existence of sodium-specific taste receptors that appear to be limited to the anterior tongue. However, previous behavioral findings suggest that bilateral transection of the chorda tympani nerve (CTn) has minimal consequences on NaCl intake and preference. This study employed a conditioned avoidance procedure to measure detection thresholds to NaCl and sucrose both before and after bilateral transection of the CTn. Rats were trained to maintain spout contact in response to water presentations (70 microliters) and to avoid spout contact when a taste solution (70 microliters) was presented. In experiment 1, all rats (n = 3) showed statistically significant impairments in the detectability of NaCl after bilateral section of the CTn. The mean increase in the NaCl detection threshold was 1.41 log units. In contrast, sucrose threshold in these same rats was marginally affected by CTn section (mean increase = 0.22 log units). Experiment 2 (n = 4) replicated the findings of the first experiment. The mean increase in the NaCl detection threshold was 2.23 log units. Sucrose threshold in these rats was, again, only marginally affected by CTn section (mean increase = 0.83 log units). Histological examination of the anterior tongue from the rats in experiment 2 indicated that the CTn transections were complete. These findings reveal that the anterior oral receptive field (innervated by the CTn) containing only 15% of the total taste bud population is critical for the normal detection of NaCl.
Effects of desipramine hydrochloride on peripheral sympathetic nerve activity
Authors: Cohen M. D. , Finberg J. , Dibner-Dunlap M. , Yuih S. N. , Thames M. D.
Published: December 2017

Tricyclic antidepressants cause orthostatic hypotension and have antiarrhythmic effects that may be partially due to effects on the sympathetic nervous system. We studied the influence of intravenous desipramine hydrochloride on renal (n = 12) and lumbar (n = 5) nerve traffic and mean arterial pressure in alpha-chloralose-anesthetized rabbits with sinoaortic and vagal denervation. Desipramine administration resulted in dose-dependent inhibition of renal and lumbar nerve activity that was markedly reduced or abolished by yohimbine (0.5 mg/kg iv), an alpha 2-blocker that enters the brain rapidly. In contrast, administration of phentolamine (0.75 mg/kg iv), an alpha 1- and alpha 2-blocker with limited access to the brain, failed to alter the responses to desipramine. Because renal nerves are postganglionic and lumbar nerves are preganglionic, desipramine does not act via a ganglionic mechanism. Our results are best explained by an effect of desipramine on the sympathetic nervous system mediated via central alpha 2-receptors. This sympathoinhibitory effect of desipramine may contribute to its postural hypotensive effect and to its efficacy as an antiarrhythmic agent.
Oxygen consumption in the fetal lamb during sustained hypoxemia with progressive acidemia
Authors: Rurak D. W. , Richardson B. S. , Patrick J. E. , Carmichael L. , Homan J.
Published: December 2017

To investigate the fetal ability to compensate for a sustained reduction in O2 delivery (DO2; umbilical blood flow X umbilical venous O2 content), studies were carried out on eight chronically instrumented fetal lambs made hypoxemic for 7.8 +/- 0.8 (+/- SE) h by lowering maternal inspired O2 concentration to 9-10%. After 1.7 h of hypoxemia, fetal arterial PO2 had fallen from 18.4 +/- 1.2 to 10.4 +/- 0.5 mmHg. Umbilical venous O2 content fell initially by 41.1 +/- 1.8%, but the fall in DO2 was only 23.7 +/- 5.6%, caused by a 29.3 +/- 7.9% rise in umbilical blood flow. Fetal O2 consumption (VO2) was increased significantly by 29.5 +/- 15.2%. However, fetal vascular pH (7.332-7.281) and base excess (0.5 to -4.3 meq/l) were decreased while blood lactate levels were increased (1.55-7.22 mM). With continued hypoxemia, the metabolic acidemia worsened and led to progressive declines in umbilical venous O2 content and DO2. However, VO2 was maintained at the control level until delivery had fallen by 72.5% and arterial pH was 6.843, at which time VO2 decreased by 37.5 +/- 10.7%. It is concluded that the ability of the fetus to compensate for sustained hypoxemia is limited by the progressive metabolic acidemia.
Hemodynamic, renal, and endocrine actions of ANF in sheep: effect of 24-h, low-dose infusions
Authors: Charles C. J. , Espiner E. A. , Cameron V. A. , Richards A. M.
Published: December 2017

The integrative and sustained effects of small increments in atrial natriuretic factor (ANF) on hemodynamic, renal, and hormonal function are still unclear. Accordingly, we have studied the sequential effects of 24-h, low-dose infusion (2.4 pmol.kg-1.min-1) of rat Ile-ANF or vehicle alone (control) in six normal sheep receiving a constant sodium intake. Compared with control observations, ANF infusions induced a threefold rise in venous plasma ANF and a sustained twofold rise in plasma guanosine 3',5'-cyclic monophosphate. Systolic arterial and right atrial pressures fell promptly and remained significantly reduced for the duration of the ANF infusions. These changes were associated with a sustained fall in plasma volume but no activation of renin-angiotensin-aldosterone system. In contrast to the other actions, ANF-induced natriuresis, which was significant in the first 8 h of infusion, was not sustained. These studies show that significant biological effects occur in response to small ANF increments (20-25 pmol/l) and indicate that hemodynamic factors, especially fall in plasma volume, are important in determining the renal response even at near-normal plasma ANF concentrations.
Spaceflight effects on biomechanical and biochemical properties of rat vertebrae
Authors: Zernicke R. F. , Vailas A. C. , Grindeland R. E. , Kaplansky A. , Salem G. J. , Martinez D. A.
Published: December 2017

The biomechanical and biochemical responses of lumbar vertebral bodies during a 12.5-day spaceflight (Cosmos 1887 biosatellite) were determined for rapidly growing rats (90-day-old, Czechoslovakian-Wistar). By use of age-matched vivarium controls (normal cage environment) and synchronous controls (simulated flight conditions), as well as a basal control group (killed before lift-off on the 1st day of flight), the combined influences of growth and space-flight could be examined. Centra of the sixth lumbar vertebrae (L6) were compressed to 50% strain at a fast strain rate while immersed in physiological buffer (37 degrees C). The body masses of vivarium and synchronous controls were significantly heavier than either the flight or basal controls. The flight group had an L6 vertebral body compressional stiffness that was 39% less than the vivarium controls, 47% less than the synchronous control, and 16% less than the basal controls. In addition, the average initial maximum load of the flight L6 was 22% less than vivarium controls and 18% less than the synchronous controls, whereas the linear compressional load of the flight group averaged 34% less than the vivarium and 25% less than the synchronous groups. The structural properties of the vertebrae from the 12.5-day-younger basal group closely resembled the flight vertebrae. Calcium, phosphorous, and hydroxyproline concentrations were not significantly different among the groups. Nevertheless, the lack of strength and stiffness development in spaceflight, coupled with a smaller proportion of mature hydroxypyridinoline cross-links, suggested that the 12.5 days of spaceflight slowed the maturation of trabecular bone in the vertebral bodies of rapidly growing rats.
Reappraisal of the Weir equation for calculation of metabolic rate
Authors: Mansell P. I. , Macdonald I. A.
Published: December 2017

In 1949 Weir (3) demonstrated that the metabolic rate calculated from respiratory gas exchange measurements is to a close approximation proportional to the difference in percentage oxygen content between inspired and expired air. Although values for the energy equivalent of oxygen consumed and for the respiratory quotient for the oxidation of various nutrients have been revised since 1949, we show that the error in the calculation remains generally below 0.5% for the oxidation of dietary carbohydrate, fat, and protein. Where the original equation is uncritically applied to situations in which other nutrients are being oxidized, the error may reach 3%, although alternative methods for calculating the metabolic rate may be similarly in error. We give the derivation from first principles of the general mathematical solution to the calculation of the metabolic rate following Weir's method. Examples are provided of the subsequent derivation of specific equations for the more precise calculation of the metabolic rate where different combinations of nutrients are being oxidized.
Vagal sensory neurons are required for lipoprivic but not glucoprivic feeding in rats
Authors: Ritter S. , Taylor J. S.
Published: December 2017

This experiment examined the role of subdiaphragmatic vagal sensory neurons in feeding stimulated by pharmacological blockade of fatty-acid oxidation (lipoprivic feeding) and glucose utilization (glucoprivic feeding). Rats prepared by surgical transection of the subdiaphragmatic vagal trunk or aspiration lesion of the vagal sensory terminal fields in the area postrema-nucleus of the solitary tract (AP-NTS) were maintained and tested on a fat-supplemented, high carbohydrate diet. Fatty-acid oxidation was blocked with mercaptoacetate (MA, 400 and 600 mumol/kg ip) and glucose utilization was blocked with 2-deoxy-D-glucose (2-DG, 100 and 200 mg/kg sc). On test days, rats were injected with MA, 2-DG, or saline, and feeding was measured hourly for 6 h beginning immediately after injection. We found that both subdiaphragmatic vagotomy and AP-NTS lesions abolished lipoprivic feeding. In contrast, glucoprivic feeding was abolished by AP-NTS lesions but not by subdiaphragmatic vagotomy. These results indicate that lipoprivic feeding requires intact subdiaphragmatic vagal sensory neurons that terminate in the AP-NTS region. Glucoprivic feeding is not vagally mediated but also requires a neural substate within the AP-NTS region.
Influence of acid-base status on plasma catecholamines during exercise in normal humans
Authors: Goldsmith S. R. , Iber C. , McArthur C. D. , Davies S. F.
Published: December 2017

The influence of acid-base status on plasma catecholamines during exercise was investigated in six healthy volunteers. Incremental exercise to 175 W was performed on a bicycle ergometer under four conditions: 1) control, 2) during forced hyperventilation (HV), 3) after pretreatment with acetazolamide (AZE), and 4) while breathing 4% CO2. Resting plasma norepinephrine (PNE) and epinephrine (PE) were not different among the four protocols despite higher resting pH during HV and lower resting pH after AZE [control, 7.4 +/- 0.02; HV, 7.48 +/- 0.03 (P less than 0.005); AZE, 7.36 +/- 0.01 (P less than 0.005) (P values indicate significant differences from the control protocol)]. Resting pH was not different from control during the 4% CO2 study (7.4 +/- 0.01). At the 175-W exercise load, there were significant differences in both pH and PNE. During the control test, pH was 7.38 +/- 0.02, PNE was 951 +/- 164 pg/ml, and PE was 264 +/- 132 pg/ml. During HV, pH was 7.46 +/- 0.5 (P less than 0.001), PNE was 976 +/- 67 pg/ml, and PE was 210 +/- 27 pg/ml. After AZE, pH was 7.31 +/- 0.2 (P less than 0.001), PNE was 1,866 +/- 561 pg/ml (P less than 0.005), and PE was 382 +/- 264 pg/ml. While subjects breathed 4% CO2, pH was 7.29 +/- 0.02 (P less than 0.001), PNE was 1.842 +/- 617 pg/ml (P less than 0.01), and PE was 467 +/- 275 pg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
Somatostatin mediates bombesin inhibition of chloride secretion by rectal gland
Authors: Silva P. , Lear S. , Reichlin S. , Epstein F. H.
Published: December 2017

The function of bombesin-like peptide, a neurotransmitter present in nerve fibers of elasmobranch rectal glands, is unknown. Since the principal activity of the rectal gland is to secrete chloride, the effects of bombesin on chloride secretion and the role of somatostatin in this response was studied. Bombesin failed to stimulate secretion in rectal glands perfused in the basal state. When added to glands stimulated by a constant infusion of vasoactive intestinal peptide (VIP), bombesin (8 x 10(-7) M) reversibly inhibited chloride secretion by 56 +/- 9.7% and at the same time evoked a 10-fold increase in the liberation of somatostatin into the venous effluent. Inactivation of somatostatin by the addition of cysteamine partially suppressed the inhibitory effect of bombesin on glandular secretion. The effect of bombesin to reduce chloride secretion was completely prevented by the calcium channel blocker nifedipine, which inhibits neurotransmitter release. These results suggest that bombesin inhibits the effect of VIP to stimulate chloride secretion by releasing somatostatin from neurosecretory nerve terminals within the rectal gland.
Metabolic control in exercising skeletal muscle
Authors: Connett R. J. , Honig C. R.
Published: December 2017

Pages R288–R290: Letters to the Editor, Reply, R. J. Connett and C. R. Honig. “Metabolic control in exercising skeletal muscle.” The sentence beginning at the very bottom of page R289 and continuing at the top of page R290 should read: “The salient feature of the system is that the concentrations of ADP, ATP, PCr, Cr, and Pi are so interdependent through the actions of creatine kinase and adenylate kinase that the system has only one degree of freedom: measurement of change in any one of the above compounds completely defines the change in any of the others (1).”
Feeding influences plasma cortisol levels during preweaning life in baboons
Authors: Lewis D. S. , Jackson E. M.
Published: December 2017

The effect of feeding on plasma cortisol concentrations was examined in neonate (preweaning), infant (postweaning), and adult baboons (Papio cynocephalus). Neonates were bottle fed four times daily, infants twice daily, and adults once daily. In neonates, plasma cortisol declined within 30 min after feeding. This decline in plasma cortisol was dependent on ingestion of formula and was independent of the time of feeding. During the day, cortisol fluctuations were synchronized with feeding times: peak levels occurred before feeding and trough levels occurred 30-60 min after feeding. Plasma adrenocorticotropic hormone (ACTH) declined within 30 min after feeding but returned to prefeeding levels at 60 min after feeding and did not exhibit significant variation associated with feeding times as did cortisol. The decline in plasma cortisol after feeding in neonates was delayed with increasing age. By 18 wk, the feed-related decline in plasma cortisol was delayed until 60 min after feeding compared with 30 min at age of 8 wk. After weaning, the decline in plasma cortisol after feeding was delayed until 90 min, and there was no effect of feeding in the afternoon on plasma cortisol. Finally, there was no significant decline at all in adult baboons greater than 6 yr of age. These results demonstrate plasma cortisol concentration is associated with feeding in neonates fed formula. The cortisol-feeding rhythm changes before weaning, and after weaning it begins to disappear, until it is completely absent in adults.
Effect of human pregnancy on metabolic clearance rate of oxytocin
Authors: Thornton S. , Davison J. M. , Baylis P. H.
Published: December 2017

The metabolic clearance rate (MCR) of oxytocin (OT) was determined by use of constant infusion techniques to achieve low and high plasma OT concentrations in 10 women in late pregnancy and again 8-10 wk postpartum (mean plasma oxytocinase activity was 2.1 IU/ml plasma at term and less than 0.1 IU/ml plasma 8-10 wk postpartum). At the lower plasma OT concentrations (5.0 and 5.2 pg/ml, pregnant and postpartum, respectively) produced by infusion of 17.9 ng/min in pregnancy and 4.3 ng/min postpartum, mean MCR of OT was increased fourfold during pregnancy (5.7 +/- 0.6 and 1.3 +/- 0.1 l/min, pregnant and postpartum, respectively; P less than 0.001). At the higher plasma OT concentrations (8.0 and 8.0 pg/ml, pregnant and postpartum, respectively) produced by infusion of 35.7 ng/min in pregnancy and 8.5 ng/min postpartum, mean MCR of OT was likewise markedly increased during pregnancy compared with postpartum values (7.1 +/- 1.9 and 1.4 +/- 0.1 l/min, respectively; P less than 0.01). The MCR of OT was independent of plasma concentration (between 5 and 8 pg/ml) during pregnancy and in the postpartum period. It is concluded that the MCR of OT is increased markedly during human pregnancy. This may be due to concomitant increases in in vivo cystine aminopeptidase activity or other less specific pregnancy-associated metabolic changes.
Antidiuretic effect of subnormal levels of arginine vasopressin in normal humans
Authors: Andersen L. J. , Andersen J. L. , Schutten H. J. , Warberg J. , Bie P.
Published: December 2017

The renal responses to 120-min infusions of arginine vasopressin (AVP) were investigated in healthy volunteers undergoing water diuresis induced by an oral water load of 20 ml/kg body wt. AVP at 1 pg.min-1.kg-1 (approximately 10(-15) mol.min-1.kg-1) decreased urine flow (12.2 +/- 1.7 to 7.4 +/- 1.5 ml/min) and free water clearance (9.7 +/- 1.5 to 4.8 +/- 1.4 ml/min) and increased urine osmolality (Uosmol; 71 +/- 6 to 115 +/- 15 mosmol/kgH2O); 5 pg.min-1.kg-1 elicited pronounced antidiuresis (14.4 +/- 0.9 to 0.9 +/- 0.3 ml/min) with maximal Uosmol of 621 +/- 95 mosmol/kg. In response to 25 pg.min-1.kg-1, maximal Uosmol was 869 +/- 38 mosmol/kg. Responses developed gradually and stabilized within the 2nd h of infusion. AVP at 1 and 5 pg.min-1.kg-1 was without effect for at least 20 min. Only 25 pg.min-1.kg-1 caused a significant rise in plasma AVP (1.2 +/- 0.2-2.0 +/- 0.1 pg/ml), and with this dose sodium excretion decreased. The rates of K+ excretion, as well as plasma aldosterone and atrial natriuretic peptide concentrations, were unaffected by AVP. It is concluded that the human kidney is sensitive to changes in the rate of secretion of AVP of less than 1 pg.min-1.kg-1 and that the maximal change occurs after 1-2 h of constant infusion. It is estimated that the rate of infusion of AVP required to produce isosmolar urine during overhydration is approximately 3 pg.min-1.kg-1.
Mechanisms of temperature acclimation in the carp: a molecular biology approach
Authors: Gerlach G. F. , Turay L. , Malik K. T. , Lida J. , Scutt A. , Goldspink G.
Published: December 2017

Most fish are unable to regulate their body temperature. Therefore their muscle power output would be expected to decline markedly with decreased environmental temperature. However, some species including carp show a remarkable ability to acclimate. The nature and significance of changes in enzymatic myosin ATPase activity and the recruitment of different muscle fiber types in relation to acclimation and environmental temperature in carp are reviewed. These changes presumably involve qualitative and quantitative changes in gene expression. To approach the problem, we have constructed a carp genomic library and isolated 28 nonoverlapping clones containing sequences of different myosin heavy chain (MHC) isoforms along with a clone containing carp actin sequences. Plasmids containing probes specific for a carp fast muscle MHC and actin RNA were constructed. Hybridization results suggest that the expression of this MHC isoform RNA is increased in warm- relative to cold-acclimated carp. These data indicate that there are different MHC isoform genes that are expressed at warm and cold environmental temperatures.
Lipocortin 1 fragment modifies pyrogenic actions of cytokines in rats
Authors: Carey F. , Forder R. , Edge M. D. , Greene A. R. , Horan M. A. , Strijbos P. J. , Rothwell N. J.
Published: December 2017

Lipocortins form a group of proteins that have been proposed as mediators of the anti-inflammatory actions of glucocorticoids. Intracerebroventricular injection of a recombinant fragment of lipocortin 1 (NH2-terminal 1-188) caused dose-dependent (0.4-1.2 micrograms) reductions in the acute increases in colonic temperature and oxygen consumption, which occurred in response to central injections of recombinant interleukin 1 beta and gamma-interferon in conscious rats. In contrast the lipocortin fragment did not affect the response to prostaglandin E2, and its activity was prevented by heat treatment or by pretreatment of animals with polyclonal antiserum raised to the fragment. Central injection of antiserum significantly enhanced the thermogenic responses to interleukin 1 beta in rats treated with dexamethasone without affecting the responses in normal animals. These results support a physiological role for lipocortin in the central effects of glucocorticoids.
Seasonal changes in mucosal structure and function in ground squirrel intestine
Authors: Carey H. V.
Published: December 2017

Seasonal variations in mucosal structure and transport function were examined in active and hibernating ground squirrel jejunum. Mucosal wet weight and protein content, villus height, and mucosal surface area were lowest in hibernators, increased in spring, peaked in summer, and declined in fall. Transepithelial electrical parameters and net Na+ and 3-O-methylglucose (3-OMG) absorption measured in flux chambers were greatly reduced in hibernator tissues tested at 7 degrees C compared with tissues from hibernators or active squirrels studied at 37 degrees C. At 37 degrees C, net Na+ and 3-OMG absorption normalized to serosal surface area was similar in tissues from all squirrels. When normalized to mucosal surface area, absorption in hibernators was greater than in spring or summer squirrels but was not significantly different from fall values. Absorption normalized to mucosal area was similar among spring, summer, and fall squirrels. Increases in short-circuit current evoked by mucosal addition of D-glucose or L-alanine were significantly greater in hibernators than in fall squirrels. These results demonstrate seasonal variations in mucosal structure and transport function in captive ground squirrels. Enhanced area-specific absorption in hibernator tissues at 37 degrees C may represent a compensatory response to pronounced mucosal atrophy that occurs during hibernation.
Mechanism of cardiac-related synchronized cardiac sympathetic nerve activity in awake cats
Authors: Ninomiya I. , Akiyama T. , Nishiura N.
Published: December 2017

To examine the mechanism of cardiac-related sympathetic discharge, the periodicity of synchronized cardiac sympathetic nerve activity (CSNA) was measured in awake cats before and after baroceptor denervation using an interval histogram. We found two major periodicities, i.e., Tc = 48-164 ms (20-6 cycles/s) and Tb = 164-512 ms (6-2 cycles/s). In the baroceptor-intact state, the modes of Tc (C) and Tb (B) were 96 ms (10 cycles/s) and 368 ms (2.7 cycles/s), respectively, whereas the cardiac interval (CI) was 366 ms (2.7 cycles/s). Probability of B mode was larger than that of C mode. During tachycardia by atropine, B mode decreased to 304 ms in proportion to CI of 308 ms, whereas C mode remained the same. Probability of B and C modes decreased reflexly by hypertension. Under baroceptor denervation, C mode remained unchanged but its probability increased significantly. A 2-6 cycles/s Tb rhythm could be found, but its probability decreased significantly. Tb periodicity consists of 2Tc, 3Tc, and 4Tc. These results suggest that C mode may reflect a fundamental periodicity of central origin and that B mode reflects a periodicity of cardiac-related synchronized CSNA, which is produced in a probabilistic manner by reflex inhibition of fundamental rhythm due to periodic baroceptor input.
31P-NMR measurements of pHi and high-energy phosphates in isolated turtle hearts during anoxia and acidosis
Authors: Wasser J. S. , Inman K. C. , Arendt E. A. , Lawler R. G. , Jackson D. C.
Published: December 2017

We used 31P-nuclear magnetic resonance (NMR) spectroscopy to measure intracellular pH (pHi) and high-energy phosphate levels in hearts of turtles (Chrysemys picta bellii) during either 4 h of anoxia [extracellular pH (pHo) 7.8, 97% N2-3% CO2], 4 h of lactic acidosis (pHo 7.0, 97% O2-3% CO2), or 1.5 h of combined anoxia + lactic acidosis (pHo 7.0, 97% N2-3% CO2) followed by 2 h of oxygenated recovery (pHo 7.8) at 20 degrees C. We also measured heart rate, maximum ventricular-developed pressure, and rate of pressure development (dP/dtmax). 31P-NMR spectra were characterized by the seven peaks typical of mammalian hearts, although turtle spectra were dominated by a large phosphodiester peak. Anoxia caused an increase in Pi to 165% and a decrease in creatine phosphate (CP) to 42% of control, whereas ATP levels remained unchanged. pHi declined from 7.37 +/- 0.01 to 7.22 +/- 0.03 at 1 h of anoxia and remained unchanged through hour 4. Lactic acidosis caused a 59% decrease in Pi, whereas CP and ATP levels remained unchanged. pHi fell to 6.88 +/- 0.04 by hour 1 and then climbed steadily to 7.14 +/- 0.05 at hour 4. During recovery from acidosis, pHi exceeded control values and returned to control by 2 h. Combined anoxia + acidosis caused profound decreases in CP to 14% and pHi to 6.56 +/- 0.03. In anoxic hearts, cardiodynamic variables remained at control levels through hour 3, after which cardiac output, heart rate, and dP/dtmax declined. Cardiodynamic variables were essentially unchanged from control throughout 4 h of acidosis except for dP/dtmax, which declined rapidly. In the combined protocol, all measures of cardiac function decreased. Recovery in all three cases was complete by approximately 2 h. We conclude that turtle hearts were relatively resistant to the stresses imposed in all three protocols compared with mammalian hearts, although anoxia + acidosis depressed the measured cardiac variables more profoundly than predicted from responses to the conditions imposed separately. Our results from the anoxia protocol suggest no direct causal relationship between myocardial CP (or ATP) levels and cardiac function.
Human serum and plasma have different sources of epidermal growth factor
Authors: Lev-Ran A. , Hwang D. L. , Snyder D. S.
Published: December 2017

Epidermal growth factor (EGF) was determined by radioimmunoassay in serum, plasma, and urine of 23 patients undergoing ablative therapy followed by bone marrow transplantation. The difference between the serum and plasma values reflected the amount of EGF released from the platelets at the time of blood coagulation. Platelet-derived EGF strongly correlated with platelet count (r + 0.850, P less than 0.0001), and the intercept of the regression line was very close to zero; one platelet contained approximately 2.5 x 10(-18) g EGF. Correspondingly, when the platelet count dropped after bone marrow ablation from 222 +/- 97 to 33 +/- 13 x 10(9)/l, the serum EGF decreased from 603 +/- 222 to 65 +/- 41 pg/ml (P less than 0.0001). Plasma EGF content did not correlate with the platelet count and did not change significantly after bone marrow ablation (before and after the ablation, correspondingly, 290 +/- 80 and 332 +/- 99 pg/ml, P = 0.194). High-performance liquid chromatographic fractionation of serum and plasma showed different molecular mass distribution of EGF-immunoreactive fractions. The main molecular mass components of the plasma EGF did not change after bone marrow ablation. Urine excretion remained unchanged (320 +/- 133 and 314 +/- 173 pmol EGF/mmol creatinine). We conclude that whereas platelets are the source of serum EGF, the origin of plasma EGF is different and the search of its origin is warranted.
Relationships between activity of sympathetic nerve pairs: phase and coherence
Authors: Kocsis B. , Gebber G. L. , Barman S. M. , Kenney M. J.
Published: December 2017

The coherence function and phase spectrum were used to study the relationships between the discharges of sets of two postganglionic or preganglionic sympathetic nerves in baroreceptor-denervated cats anesthetized with either 5,5-diallylbarbiturate-urethan or alpha-chloralose. Most of the power in sympathetic nerve discharge was contained between 2 and 6 Hz. The coherence values relating the activity of two nerves were significantly different from zero within this frequency band. The phase spectrum was either linear or complex (i.e., showed changes in slope) within the coherent frequency band. We observed three patterns of relationship. The first pattern was characterized by a constant interval between activity in different sympathetic nerves within the coherent frequency band. The second pattern was characterized by a frequency-dependent interval. The third pattern was characterized by uncoupling of the 2- to 6-Hz rhythms in the discharges of different nerves. Switching between these patterns was observed. We suggest that the three patterns reflect different functional states of the central system responsible for the 2- to 6-Hz rhythm. Two models of this system are entertained. The first model is one of a system of coupled oscillators while filtering circuits that receive common inputs are the elements of the second model.
Coherence of medullary unit activity and sympathetic nerve discharge
Authors: Gebber G. L. , Barman S. M. , Kocsis B.
Published: December 2017

Analyses in the frequency and time domains were used to study the relationships between the discharges of single brain stem neurons and postganglionic sympathetic nerves in baroreceptor-innervated and -denervated cats anesthetized with 5,5-diallylbarbiturate-urethan. Spike-triggered averaging was used initially to identify single neurons with sympathetic nerve-related activity in the medullary lateral tegmental field, rostral ventrolateral medulla, and medullary raphe. The discharges of such neurons were correlated to the 2- to 6-Hz rhythm in sympathetic nerve discharge (SND). Frequency-domain analysis revealed that the relationship between medullary unit activity and the sympathetic nerve rhythm was not fixed from cycle to cycle. First, the coherence values relating the activity of these neurons to SND were closer to zero than to unity in most cases. Second, whereas most of the power in the autospectra of SND was contained between 2 and 6 Hz, that in the autospectra of medullary unit activity was more evenly distributed over a much wider frequency band. These and other observations indicate that the 2- to 6-Hz rhythm is an emergent property of a network of brain stem neurons whose discharges are probabilistically rather than strictly related to the phases of the population rhythm.
Effects of baroreceptor denervation on endocrine and drinking responses to caval constriction in dogs
Authors: Quillen E. W. , Keil L. C. , Reid I. A.
Published: December 2017

Plasma arginine vasopressin (AVP), plasma renin activity (PRA), and water intake (H2OIN) are increased by thoracic inferior vena caval constriction (TIVCC). To assess the role of the cardiac and sinoaortic baroreceptors in these responses, 9 sham-, 10 cardiac-(CD), 6 sinoaortic-(SAD), and 4 combined cardiac and sinoaortic-(CD + SAD) denervated conscious dogs were studied. All animals were studied while normally hydrated 1) with no access to water (H2O-) and 2) while drinking was permitted (H2O+). TIVCC caused similar reductions (P less than 0.001) of mean arterial (-32 +/- 4 mmHg), left atrial pressure (-6.5 +/- 1.1 cmH2O), and right atrial pressure (-4.2 +/- 0.8 cmH2O) in all groups. After TIVCC in sham dogs with H2O-, AVP increased from 3.6 +/- 0.7 to 72.8 +/- 12.6 pg/ml (P less than 0.001). AVP was similar with SAD (57.1 +/- 6.9) but was reduced with CD (30.9 +/- 3.0) and CD + SAD (17.7 +/- 4.0). In all groups, PRA increased from 4.5 +/- 0.7 to 23.8 +/- 3.0 ng.ml-1 x 3 h-1 and plasma angiotensin II (ANG II) increased from 14.0 +/- 2.8 to 59.5 +/- 13.0 pg/ml (P less than 0.001). Plasma adrenocorticotropic hormone (ACTH) increased similarly in all groups (55 +/- 5 to 128 +/- 25 pg/ml). Plasma norepinephrine (NE) levels increased similarly in all groups (298 +/- 61 to 654 +/- 88 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
Roles of interleukin 1 beta and tumor necrosis factor in lipopolysaccharide fever in rats
Authors: Long N. C. , Otterness I. , Kunkel S. L. , Vander A. J. , Kluger M. J.
Published: December 2017

The roles of interleukin 1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF) in lipopolysaccharide (LPS)-induced fever were investigated in the rat. We used antisera against IL-1 beta and TNF to determine whether we could alter the fever by blocking the action of these cytokines. The intravenous injection of antiserum IL-1 beta 3.5 days before the intraperitoneal injection of LPS resulted in a mean fever that was significantly lower than that seen in rats that had been injected with control serum (0.36 +/- 0.11 vs. 0.82 +/- 0.16 degrees C, P = 0.016). The intravenous injection of antiserum against TNF 3.5 days before the intraperitoneal injection of LPS did not block the fever but significantly enhanced it (1.31 +/- 0.16 vs. 0.82 +/- 0.16 degrees C, P = 0.027). These data support the hypotheses that IL-1 beta is responsible for a significant part of LPS fever and that TNF acts as an endogenous antipyretic to limit the magnitude of LPS fever in the rat.
Angiotensin and salt appetite of BALB/c mice
Authors: Denton D. A. , Blair-West J. R. , McBurnie M. , Osborne P. G. , Tarjan E. , Williams R. M. , Weisinger R. S.
Published: December 2017

The influence of systemic or intracerebroventricular (icv) administration of angiotensin II on the intakes of NaCl solution, water, and food was investigated in BALB/c mice. Systemic administration of angiotensin II had little, if any, influence on these ingestive behaviors. On the other hand, icv infusion of angiotensin II at 70 ng/day increased (P less than 0.05) intakes of NaCl solution and water by the third day of infusion. The amount of NaCl ingested daily during the infusion was two to three times body sodium content. The mean daily water intake increased to 40-60% of body weight. The vast increase in NaCl intake was not secondary to a natriuresis caused by the icv infusion of angiotensin II. The results suggest that angiotensin II has a direct effect on neural systems involved in sodium appetite in this species.
Effects of reduced uterine blood flow on fetal cardiovascular, renal, and lung function
Authors: Stevens A. D. , Lumbers E. R.
Published: December 2017

Uterine blood flow (UBF) was reduced for 1 h by partially occluding the maternal aorta below the renal arteries in seven pregnant ewes (gestation age 126-134 days). Fetuses became hypoxic, acidemic, and hypercapnic. They developed hypertension (P less than 0.005) and a bradycardia (P less than 0.05). During restricted UBF, fetal hematocrit (Hct) rose (P less than 0.005) and blood volume fell in five of seven fetuses. After release of constriction, fetal Hct fell, and blood volume rose by 7.5 +/- 3.26% (P less than 0.05) relative to control. During reduced UBF, lung liquid and urine flow rates fell (P less than 0.025 and P less than 0.05, respectively). After the occluder was released, Na excretion (which did not fall significantly during reduced UBF) increased (P less than 0.05), and fractional reabsorption of Na fell (P less than 0.05). Changes in fetal blood volume (FBV) were directly related to changes in maternal lower body flow (r = 0.47, P = 0.01, n = 33), and changes in fetal Hct were inversely related to maternal flow (r = -0.635, P = 0.001). Fetal urinary Na excretion per kilogram body weight was directly related to FBV per kilogram (r = 0.44, P = 0.005, n = 40), whereas fractional reabsorption of Na was inversely related to FBV per kilogram body wt (r = 0.48, P less than 0.002, n = 39). It is concluded that reductions in UBF cause fetal hypoxemia and acidemia, which lead to changes in fetal cardiovascular function and in FBV.(ABSTRACT TRUNCATED AT 250 WORDS)
Salt sensitivity in hypertensive rats with angiotensin II administration
Authors: Ando K. , Sato Y. , Fujita T.
Published: December 2017

We examined the salt sensitivity of blood pressure in angiotensin II (ANG II)-induced hypertension. Wistar rats, salt loaded (0.66, 2, or 8% salt-containing diet) for 4 or 12 days, were infused intravenously with 15 or 60 ng/min of ANG II. Systolic blood pressure (SBP) was not increased by long-term (12 days) salt loading, and SBP was unchanged with ANG II and normal-salt (0.66%) diet. However, when combined with salt loading, ANG II produced hypertension in a dose-dependent fashion; compared with control (120 +/- 2 mmHg), SBP was increased with 15 ng/min of ANG II and 8% salt diet (145 +/- 5 mmHg, P less than 0.05) and with 60 ng/min of ANG II and either 2 or 8% salt diet (149 +/- 8 and 174 +/- 8 mmHg, P less than 0.05, respectively). Na space (exchangeable Na) was increased in a roughly similar pattern and correlated significantly (r = 0.531, P less than 0.05) with SBP. However, with 15 ng/min of ANG II, Na space was not different among rats on either level of salt loading, although the 8% salt diet elevated SBP. Data obtained with short-term (4 days) treatment indicate that an elevated Na space preceded development of hypertension. With 15 ng/min of ANG II and 8% salt diet for 4 days, Na space was markedly (P less than 0.05) increased, but SBP was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
Different in vivo metabolic activities of suprachiasmatic nuclei of Turkish and golden hamsters
Authors: Schwartz W. J.
Published: December 2017

The 14C-labeled 2-deoxy-D-glucose technique was used to measure in vivo glucose utilization of the suprachiasmatic nuclei (SCN) of Turkish and golden hamsters during the middle hours of the light phase of the 12:12 h light-dark cycle. The nuclei were clearly visible on autoradiographs made from the brains of Turkish hamsters, and their rate of glucose utilization (69 +/- 6 mumol.100 g-1.min-1) was similar to that previously measured in other rodents, whereas the nuclei were hardly visible on autoradiographs from golden hamsters, and their rate (33 +/- 2 mumol.100 g-1.min-1) was less than half this value. Thus the high energy metabolism characteristic of the SCN of most species is not required for the circadian pacemaker in the nuclei to generate its oscillation.
p-Chloromercurobenzene sulfonate inhibition of active Cl- transport in plasma membrane vesicles from Aplysia gut
Authors: Gerencser G. A.
Published: December 2017

Both a Cl(+)-stimulated adenosinetriphosphatase (ATPase) activity and an ATP-dependent Cl- transport process were found in Aplysia foregut absorptive cell plasma membranes. In an attempt to further characterize this transport process, plasma membrane vesicles from Aplysia foregut absorptive cells were prepared utilizing differential centrifugation and sucrose density-gradient techniques. Sulfhydryl ligand participation in ATP-dependent Cl- transport was confirmed in three ways. First, 1,4-dithiothreitol partially restored a p-chloromercurobenzene sulfonate (PCMBS)-inhibited ATP-dependent Cl- transport. Second, 1,4-dithiothreitol restored intravesicular negativity inhibited by PCMBS. Third, 1,4-dithiothreitol had no effect on either ATP-dependent Cl- transport or ATP-dependent intravesicular negativity inhibited by N-ethylmaleimide. These results are consistent with the hypothesis that surface sulfhydryl groups participate in the functioning of the active electrogenic Cl- transport mechanism in Aplysia gut.
Model of spontaneous obesity in aging male Wistar rats
Authors: Newby F. D. , DiGirolamo M. , Cotsonis G. A. , Kutner M. H.
Published: December 2017

We analyzed retrospectively data from 148 chow-fed male Wistar rats killed between the age of 6 wk and 2 yr while varying in body weight from 136 to 917 g. The purpose of this study was to clarify the relationship of body weight and body lipid content with the composition and cellularity of the epididymal and retroperitoneal fat depots. A positive linear association was found between body weight and body water or fat-free dry residue, whereas total body lipid exhibited a curvilinear relationship with body weight. The weight of the epididymal pads was linearly related to body weight but not to body lipid. In contrast, retroperitoneal pad weight was exponentially related to body weight and paralleled total body lipid. A strong linear correlation was found between total body lipid and weight (r = 0.959) or depot lipid content (r = 0.967) of the retroperitoneal fat pads. In this rat model of aging and spontaneous obesity, significant regional differences exist in adipose depot composition and cellularity. A practical outcome of this study is a simple and accurate prediction of body lipid content from the gravimetric determination of the retroperitoneal fat depots.