Prolactinotrophic effect of endogenous and exogenous heat loads in human male adults

1991 ◽  
Vol 70 (3) ◽  
pp. 1351-1355 ◽  
Author(s):  
G. R. Brisson ◽  
F. Peronnet ◽  
H. Perrault ◽  
P. Boisvert ◽  
D. Massicotte ◽  
...  
Keyword(s):  
Water Immersion ◽  
Venous Blood ◽  
Water Control ◽  
Beta Endorphin ◽  
Warm Environment ◽  
Heat Loading ◽  
Before And After ◽  
Blood Hormones ◽  
Heat Loads ◽  
Face Cooling

Factors associated with heat-induced increase in blood prolactin (PRL) were investigated. Ten male volunteers (23.7 +/- 2.2 yr) were exposed to exogenous heating (head-out immersion) in 41 degrees C water (control 37 degrees C) for 30 min with and without face fanning and cooling. In seven of the subjects, endogenous heating was produced by a 45-min exercise in a warm environment (41 degrees C; control 10 degrees C) with and without selective face fanning. Venous blood was collected before and after each trial; blood hormones were analyzed by radioimmunologic techniques. Heat loading, whether exogenous or endogenous in origin, induced significant increases in blood PRL, beta-endorphin, and vasoactive intestinal peptide (VIP) levels. Blood thyrotropin (TSH) level decreased significantly during water immersion and more significantly with face cooling. From measurement in peripheral blood, the differential beta-endorphin, VIP, and TSH responses to selective face ventilation during exogenous and endogenous heat exposures suggest that blood PRL released in heat derives from secretory stimuli that are independent of these prolactinotropic factors.

Carotid sinus baroreflex control of beta-endorphin release in anesthetized dogs

1989 ◽  
Vol 256 (2) ◽  
pp. R408-R412
Author(s):  
M. J. Brunner ◽  
K. E. Wehberg ◽  
J. C. Williams ◽  
C. A. Cahill
Keyword(s):  
Carotid Sinus ◽  
Venous Blood ◽  
Normal Component ◽  
Vagal Afferents ◽  
Mixed Venous Blood ◽  
Baroreflex Control ◽  
Beta Endorphin ◽  
Carotid Sinus Baroreflex ◽  
Before And After ◽  
Anesthetized Dogs

A quantitative assessment of the carotid sinus baroreflex release of endogenous plasma beta-endorphin-like immunoreactive material has been established. The carotid sinuses of 12 pentobarbital sodium-anesthetized dogs were isolated bilaterally and perfused with a constant pressure maintained by infusion or withdrawal of normal saline. Mean arterial pressure (MAP) and heart rate (HR) were monitored. Carotid sinus pressure (CSP) was changed from 200 to 50 mmHg in 25 mmHg steps before and after vagotomy. At each interval of CSP, 10 ml mixed venous blood were collected, and beta-endorphin-like peptides were extracted from plasma and assayed. Concentrations of plasma beta-endorphin-like material were determined by radioimmunoassay. Sigmoidal responses of MAP and HR were revealed during changes in CSP. No significant differences in beta-endorphin-like immunoreactivity (beta-END-L-I) were measured at CSP of 200 and 50 in the intact condition (35.9 +/- 3.9 and 35.0 +/- 6.4 fm/ml, respectively). However, after vagotomy, beta-END-L-I measured at 50 mmHg CSP was significantly elevated to 53.3 +/- 5.2 fm/ml compared with the value of 35.5 +/- 7.2 fm/ml at CSP of 200 mmHg. The results suggest that the release of beta-endorphin is modulated by the action of the carotid baroreflex as a normal component of an integrated efferent response. However, this response is normally buffered by reflexes with vagal afferents.

Increases in plasma beta-endorphin/beta-lipotropin immunoreactivity after treadmill running in humans

1982 ◽  
Vol 52 (5) ◽  
pp. 1245-1249 ◽  
Author(s):  
P. A. Farrell ◽  
W. K. Gates ◽  
M. G. Maksud ◽  
W. P. Morgan
Keyword(s):  
Plasma Levels ◽  
Control Experiment ◽  
Mood State ◽  
Venous Blood ◽  
Time Of Day ◽  
Treadmill Running ◽  
Large Individual ◽  
Beta Endorphin ◽  
Before And After ◽  
Radio Immunoassay

Six well-trained endurance athletes were studied to determine if submaximal treadmill exercise results in increased plasma levels of beta-endorphin/beta-lipotropin (Bh-Ep/Bh-LPH) immunoreactivity. Bh-Ep/Bh-LPH immunoreactivity was measured by radio immunoassay in plasma from six experienced runners before and after 30-min treadmill runs at a self-selected pace, 60 and 80% VO2 max, and a control experiment of 30 min rest. All tests were randomized and occurred during the same time of day for a given subject (0600--1500 h). Preexercise Bh-Ep/Bh-LPH values averaged between 10 and 20 pg/ml and increased two- to fivefold after each run. The increase was statistically significant (P less than 0.05) only after the 60% run when Bh-Ep/Bh-LPH increased to a mean of 58.3 pg/ml. A large individual variation in the Bh-Ep/Bh-LPH response to running was noted. Mood state and perceptual data were also collected, and no significant relationship with Bh-Ep/Bh-LPH was evident. These data suggest that the stress of treadmill running acts as a stimulus to greater Bh-Ep/Bh-LPH secretion, a reduction in its degradation, or a combination of these, which leads to increased levels of these ligands in venous blood. The physiological significance of these increased plasma levels is not clear.

ADRENAL 17-HYDROXYCORTICOSTEROID SECRETION IN THE DOG IN RESPONSE TO ETHANOL

1972 ◽  
Vol 70 (4) ◽  
pp. 736-740 ◽  
Author(s):  
T. Suzuki ◽  
R. Higashi ◽  
T. Hirose ◽  
H. Ikeda ◽  
K. Tamura
Keyword(s):  
Venous Blood ◽  
Secretion Rate ◽  
Conscious Dogs ◽  
Blood Samples ◽  
Before And After

ABSTRACT Conscious dogs were infused intravenously with ethanol in doses of 0.7 and 1.0 g/kg. The adrenal venous blood samples were collected before and after the infusion of ethanol and analysed for 17-hydroxycorticosteroids (17-OHCS). After the infusion of 0.7 g/kg (subanaesthetic dose) of ethanol the adrenal 17-OHCS secretion rate showed either a slight increase or no change. After the infusion of 1.0 g/kg (anaesthetic dose) of ethanol the adrenal 17-OHCS secretion rate increased markedly and reached 1.21±0.15 (mean±sem) μg/kg/min, while it was 0.09±0.023 μg/kg/min before the infusion.

Plasma volumes and constituents of heat-exposed men before and after acclimatization

1975 ◽  
Vol 38 (4) ◽  
pp. 570-575 ◽  
Author(s):  
L. C. Senay
Keyword(s):  
Water Movement ◽  
Venous Blood ◽  
Heat Exposure ◽  
Heat Acclimatization ◽  
Vascular Volume ◽  
Exercise Regimen ◽  
Body Weights ◽  
Before And After ◽  
Body Compartments ◽  
Considerable Loss

Five men underwent a 2-wk exercise regimen and were then exposed to 45 degrees C db, 28 degrees C wb, wind speed 1 m/s for 12 h while at rest. Body weight was maintained with 0.1% saline. One week later the exposure was repeated without rehydration. After heat acclimatization, the 12-h experiments were repeated. Frequent body weights, rectal temperatures, and venous blood samples were obtained. Results indicated that hemodilution upon acute heat exposure is partially due to protein influx into the vascular volume and the hemodilution allowed considerable loss of body water before plasma volume returned to preexposure values. Water within the vascular volume appeared to be in equilibrium with that in other body compartments before but not after acclimatization. Acclimatization altered the rate of protein transfer (and water movement) such that hemodilution was accomplished more rapidly than before acclimatization. Early hemodilution was quite labile and depended upon subject hydration during the first hour of heat exposure.

Muscle glycogen availability and temperature regulation in humans

1989 ◽  
Vol 66 (1) ◽  
pp. 72-78 ◽  
Author(s):  
L. Martineau ◽  
I. Jacobs
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Temperature Regulation ◽  
Vastus Lateralis ◽  
Water Immersion ◽  
Vastus Lateralis Muscle ◽  
Glycogen Concentration ◽  
Exercise Regimen ◽  
Before And After ◽  
Muscle Groups

The effects of intramuscular glycogen availability on human temperature regulation were studied in eight seminude subjects immersed in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each subject was immersed three times over a 3-wk period. Each immersion followed 2.5 days of a specific dietary and/or exercise regimen designed to elicit low (L), normal (N), or high (H) glycogen levels in large skeletal muscle groups. Muscle glycogen concentration was determined in biopsies taken from the vastus lateralis muscle before and after each immersion. Intramuscular glycogen concentration before the immersion was significantly different among the L, N, and H trials (P less than 0.01), averaging 247 +/- 15, 406 +/- 23, and 548 +/- 42 (SE) mmol glucose units.kg dry muscle-1, respectively. The calculated metabolic heat production during the first 30 min of immersion was significantly lower during L compared with N or H (P less than 0.05). The rate at which Tre decreased was more rapid during the L immersion than either N or H (P less than 0.05), and the time during the immersion at which Tre first began to decrease also appeared sooner during L than N or H. The results suggest that low skeletal muscle glycogen levels are associated with more rapid body cooling during water immersion in humans. Higher than normal muscle glycogen levels, however, do not increase cold tolerance.

Costal diaphragmatic O2 and lactate extraction in laryngeal hemiplegic ponies during exercise

1988 ◽  
Vol 65 (4) ◽  
pp. 1723-1728 ◽  
Author(s):  
M. Manohar ◽  
T. E. Goetz ◽  
D. Nganwa
Keyword(s):  
Maximal Exercise ◽  
Venous Blood ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Hemoglobin Concentration ◽  
Insignificant Change ◽  
Resistive Breathing ◽  
O2 Extraction ◽  
Before And After ◽  
Arterial Po2

Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below that in normal ponies, but because of higher hemoglobin concentration, arterial O2 content exceeded that in normal ponies. Because of their high PaCO2 during ME, acidosis was more pronounced in LH animals despite similar lactate values. Diaphragmatic venous PO2 and O2 saturation decreased with ME to 15.5 +/- 0.9 Torr and 18 +/- 0.5%, respectively, at 120 s of exercise in normal ponies. In LH ponies, corresponding values were significantly less: 12.4 +/- 1.3 Torr and 15.5 +/- 0.7% at 120 s and 9.8 +/- 1.4 Torr and 14.3 +/- 0.6% at 240 s of ME. Mean phrenic O2 extraction plateaued at 81 and 83% in normal and LH animals, respectively. Significant differences in lactate concentration between arterial and phrenic-venous blood were not observed during ME. It is concluded that PO2 and O2 saturation in the phrenic-venous blood of normal ponies do not reach their lowest possible values even during ME. Also, the healthy equine diaphragm, even with the added stress of inspiratory resistive breathing, did not engage in net lactate production.

Effect of carbohydrate ingestion on exercise metabolism

1988 ◽  
Vol 65 (4) ◽  
pp. 1553-1555 ◽  
Author(s):  
M. Hargreaves ◽  
C. A. Briggs
Keyword(s):  
Muscle Glycogen ◽  
Venous Blood ◽  
Cycle Ergometer ◽  
Strenuous Exercise ◽  
Carbohydrate Ingestion ◽  
Ergometer Exercise ◽  
Glucose Polymer ◽  
Before And After ◽  
Plasma Insulin Levels ◽  
Glycogen Utilization

Five male cyclists were studied during 2 h of cycle ergometer exercise (70% VO2 max) on two occasions to examine the effect of carbohydrate ingestion on muscle glycogen utilization. In the experimental trial (CHO) subjects ingested 250 ml of a glucose polymer solution containing 30 g of carbohydrate at 0, 30, 60, and 90 min of exercise; in the control trial (CON) they received an equal volume of a sweet placebo. No differences between trials were seen in O2 uptake or heart rate during exercise. Venous blood glucose was similar before exercise in both trials, but, on average, was higher during exercise in CHO [5.2 +/- 0.2 (SE) mmol/l] compared with CON (4.8 +/- 0.1, P less than 0.05). Plasma insulin levels were similar in both trials. Muscle glycogen levels were also similar in CHO and CON both before and after exercise; accordingly, there was no difference between trials in the amount of glycogen used during the 2 h of exercise (CHO = 62.8 +/- 10.1 mmol/kg wet wt, CON = 56.9 +/- 10.1). The results of this study indicate that carbohydrate ingestion does not influence the utilization of muscle glycogen during prolonged strenuous exercise.

scholarly journals Study on the Microscopic Mechanism of Spontaneous Combustion and Oxidation Kinetics of Water-Leached Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Naifu Cao ◽  
Gang Wang ◽  
Yuntao Liang
Keyword(s):  
Kinetic Model ◽  
Moisture Content ◽  
Spontaneous Combustion ◽  
Water Immersion ◽  
Combustion Process ◽  
Oxidation Kinetic ◽  
Oxidation Mechanism ◽  
Temperature Oxidation ◽  
Before And After ◽  
Spontaneous Combustion Of Coal

In this article, a series of experiments have been carried out to study the spontaneous combustion and oxidation mechanism of coal after water immersion and investigate its tendency to spontaneous combustion, analyze the difficulty of spontaneous combustion of coal samples under different water immersion conditions, and establish a kinetic model of water immersion coal oxidation (taking the Bulianta 12# coal as a case study). They rely on physical oxidation adsorption, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry, and oil bath heating. SEM has been used to analyze the characteristics of coal pore structure under different water immersion conditions (water-saturated coal samples under different water loss conditions until the coal samples are completely dried); FTIR served to investigate the characteristics of the molecular chemical structure of the coal surface before and after the coal is immersed in water. Through programmed temperature oxidation experiments combined with FTIR analyses and gas chromatographic (GC) analysis of gaseous products, it has been possible to study the changes of molecular structure and gas products on the surface of coal samples at different temperatures and water immersion conditions. The oxidation reaction rate of the 12# coal samples of Shendong Mine’s Bulianta Mine under different water content conditions during the spontaneous combustion process has been quantitatively studied. The difficulty of spontaneous combustion of coal samples has been correspondingly addressed. A kinetic model from the perspective of oxygen consumption has been proposed. Thermogravimetry-differential scanning calorimetry (TG-DSC) has been used to analyze and study the exothermal oxidation process before and after coal immersion. From the perspective of the exothermic intensity of the coal-oxygen reaction, an oxidation kinetic model for immersed coal samples has been developed to qualitatively determine its spontaneous combustion tendency. Results have shown that the increase in the specific surface area increases the risk of spontaneous combustion, and coal samples after soaking and drying have a stronger tendency to spontaneous combustion than raw coal. The moisture content of the coal sample leading to the easiest ignition conditions is 16.05%. Regardless of the moisture content, the critical temperature is maintained at 65–75°C, and the temperature of the left coal in the goaf should be prevented from exceeding this critical value.

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