The effect of alpha2-adrenoceptor stimulation with guanfacin on thermogenesis in fasted and fed sheep

1995 ◽  
Vol 75 (4) ◽  
pp. 537-542 ◽  
Author(s):  
J. O. O. Miaron ◽  
R. J. Christopherson ◽  
R. T. Hardin
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Open Circuit ◽  
High Dose ◽  
Plasma Parameters ◽  
Blood Haemoglobin ◽  
High Doses ◽  
Haemoglobin Content

Eight sheep with an average body weight of 99 kg were divided into two groups (fasted and fed) of four and kept in individual pens. The sheep were used to examine the effects of alpha2-adrenoceptor stimulation on heat production, heart rate, rectal temperature, skin temperature and plasma parameters. On the day of the experiment, food but not water was withheld from the fasted group and the fed group received 1.0 kg of pelleted alfalfa diet. The treatments consisting of vehicle (saline) and three levels (low = 0.8 mg; medium = 1.6 mg; high = 2.4 mg per sheep) of guanfacin were administered intravenously in a split-plot experimental design. The heat production was determined by open circuit respiration calorimetry, the heart rate was recorded by an electrocardiograph and the rectal and skin temperatures were measured with a Fisher Digital Thermometer. When compared to saline, guanfacin reduced (P < 0.05) the heat production of fasted sheep (1.21 vs. 0.99, 1.09, 0.98 W kg−1) for the low, medium and high doses, respectively. For the fed sheep the medium and high doses reduced total post-feeding heat production (1.64 vs. 1.43, 1.55 W kg−1). The difference in heat production between the fed and fasted animals was not altered by guanfacin. The skin temperature was reduced by all doses of guanfacin in the fasted sheep but only by the high dose in the fed sheep. The heart rate was not affected by guanfacin. The high dose increased the rectal temperature of fed sheep. In both groups the high dose resulted in a decrease (P < 0.05) in blood haemoglobin content. Guanfacin induced a two- to threefold increase in plasma glucose and a transient response in insulin concentration. We conclude that short-term alpha2-adrenoceptor stimulation with guanfacin suppresses the heat production of both fasted and fed sheep but has no effect on the heat increment of feeding. Key words: Calorimetry, alpha2-adrenoceptors, guanfacin, feeding, sheep

Acclimatization of calves to a hot humid environment

1959 ◽  
Vol 52 (3) ◽  
pp. 305-312 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Metabolic Heat ◽  
Hot Environment ◽  
Humid Environment ◽  
Physiological Reactions

1. Three calves were exposed in a climatic room to an environment of 40° C. dry-bulb and 38° C. wet-bulb temperature for up to 110 min. each day for 1-2 weeks.2. These exposures produced progressive changes in the physiological reactions of the animals to heat:(a) Rectal temperature and skin temperature (for a given time of exposure) declined. In consequence there was a marked increase in the tolerance time, i.e. in the time for which the animals could withstand the hot environment before reaching a rectal temperature of 42° C.(b) Respiratory rate rose earlier and assumed higher levels (for given levels of body temperature).(c) Heart rate decreased markedly.3. These changes are discussed in relation to heat loss and heat production and have been interpreted as reflecting chiefly a reduction in the metabolic heat production of the animals.

Acclimatization of calves to a hot dry environment

1959 ◽  
Vol 52 (3) ◽  
pp. 296-304 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Physiological Reactions

1. Three calves were individually exposed in a climatic room to an environment of 45° C. dry-bulb and 28° C. wet-bulb temperature for 21 successive days up to 5 hr. each day.2. In the 21-day period, mostly during the first half of it, the following changes in the physiological reactions of the animals were observed: progressive reductions in rectal temperature, in heart rate and in respiratory rate with a change of breathing from a laboured to a less laboured type.3. It was suggested that a decrease in metabolic heat production might play a part in the observed acclimatization.

Effects of caffeine on blood pressure, heart rate, and forearm blood flow during dynamic leg exercise

1998 ◽  
Vol 85 (1) ◽  
pp. 154-159 ◽  
Author(s):  
Jason W. Daniels ◽  
Paul A. Molé ◽  
James D. Shaffrath ◽  
Charles L. Stebbins
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Systolic Blood Pressure ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Forearm Blood Flow ◽  
Dynamic Exercise ◽  
Ang Ii ◽  
Leg Exercise

This study examined the acute effects of caffeine on the cardiovascular system during dynamic leg exercise. Ten trained, caffeine-naive cyclists (7 women and 3 men) were studied at rest and during bicycle ergometry before and after the ingestion of 6 mg/kg caffeine or 6 mg/kg fructose (placebo) with 250 ml of water. After consumption of caffeine or placebo, subjects either rested for 100 min (rest protocol) or rested for 45 min followed by 55 min of cycle ergometry at 65% of maximal oxygen consumption (exercise protocol). Measurement of mean arterial pressure (MAP), forearm blood flow (FBF), heart rate, skin temperature, and rectal temperature and calculation of forearm vascular conductance (FVC) were made at baseline and at 20-min intervals. Plasma ANG II was measured at baseline and at 60 min postingestion in the two exercise protocols. Before exercise, caffeine increased both systolic blood pressure (17%) and MAP (11%) without affecting FBF or FVC. During dynamic exercise, caffeine attenuated the increase in FBF (53%) and FVC (50%) and accentuated exercise-induced increases in ANG II (44%). Systolic blood pressure and MAP were also higher during exercise plus caffeine; however, these increases were secondary to the effects of caffeine on resting blood pressure. No significant differences were observed in heart rate, skin temperature, or rectal temperature. These findings indicate that caffeine can alter the cardiovascular response to dynamic exercise in a manner that may modify regional blood flow and conductance.

Dose-Related Heart-Rate, Perceptual, and Decisional Changes in Man following Marihuana Smoking

1977 ◽  
Vol 44 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Carl F. Schaefer ◽  
C. G. Gunn ◽  
Kurt M. Dubowski
Keyword(s):  
Heart Rate ◽  
Information Processing ◽  
Reaction Times ◽  
Latin Square ◽  
Linear Increase ◽  
High Dose ◽  
General Tendency ◽  
Dose Control ◽  
High Doses ◽  
Oddity Discrimination

Information processing was tested in 12 male subjects after smoking marihuana containing 0, 10, or 20 mg. of delta-9-tetrahydrocannabinol (THC) in three consecutive experimental sessions according to a Latin square protocol. Successful dose control was indicated both by the dose-related linear increase observed in heart rate and by preliminary assays of THC metabolites excreted in the urine. During tachistoscopic presentation of varying numbers of circles, statistically significant decrements in information processing occurred as a function of THC dosage. However, adding irrelevant information (triangles) to the display of circles eliminated effects of marihuana on accuracy of counting. Complex reaction times for oddity discrimination increased significantly only after the high dose. Nonetheless, both the social and high doses inappropriately inhibited the general tendency to respond to changing stimuli during oddity discrimination. Marihuana had no effect on field-dependence as measured by the Rod-and-frame test.

Circadian rhythm of heat production, heart rate, and skin and core temperature under unmasking conditions in men

1994 ◽  
Vol 267 (3) ◽  
pp. R819-R829 ◽  
Author(s):  
K. Krauchi ◽  
A. Wirz-Justice
Keyword(s):  
Heart Rate ◽  
Circadian Rhythm ◽  
Heat Loss ◽  
Rectal Temperature ◽  
Heat Production ◽  
Circadian Variation ◽  
Bed Rest ◽  
Sodium Potassium ◽  
Hands And Feet ◽  
Skin Temperatures

Seven healthy men were studied in a 34-h constant routine protocol to investigate whether the daily rhythm of heat production and heat loss has an endogenous circadian component. Under these unmasking conditions (constant bed rest, no sleep allowed, regular food and fluid intake), a significant circadian rhythm could be demonstrated for heat production, heart rate, and skin temperatures but not for the respiratory quotient. Heat production and heart rate were phase locked with a maximum at 1100-1200 h. Proximal skin temperatures (infraclavicular region, thigh, and forehead) followed the same circadian rhythm as rectal temperature, whereas distal skin temperatures (hands and feet) were opposite in phase. These physiological circadian rhythm parameters, as well as biochemical parameters (urinary sodium, potassium, urea, and urine flow), were phase advanced by 25-180 min with respect to the circadian rhythm in rectal temperature. Our findings under unmasking conditions show that the circadian variation in rectal temperature is a consequence of endogenous circadian rhythms in both heat production and heat loss.

Observations on the effect of salicylate in fever and the regulation of body temperature against cold

1976 ◽  
Vol 54 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Q. J. Pittman ◽  
W. L. Veale ◽  
K. E. Cooper
Keyword(s):  
Body Temperature ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Intravenous Infusion ◽  
Sodium Salicylate ◽  
Single Injection ◽  
Continuous Intravenous Infusion ◽  
Skin Temperatures

Prostaglandins appear to be mediators, within the hypothalamus, of heat production and conservation during fever. We have investigated a possible role of prostaglandins in the nonfebrile rabbit during thermoregulation in the cold. Shorn rabbits were placed in an environment of 20 °C, and rectal and ear skin temperatures, shivering and respiratory rates were measured. A continuous intravenous infusion of leucocyte pyrogen was given to establish a constant fever of approximately 1 °C, and after observation of a stable febrile temperature for 90 min, a single injection of 300 mg of sodium salicylate, followed by a 1.5 mg/min infusion was then given. After the salicylate infusion was begun, rectal temperature began to fall, and reached nonfebrile levels within 90 min. Shivering activity ceased, respiratory rates increased, and in two animals, ear skin temperature increased. When these same rabbits were placed in an environment of 10 °C, at a time they were not febrile, and an identical amount of salicylate was given, rectal and ear skin temperatures, shivering and respiratory rates did not change. These results indicate that prostaglandins do not appear to be involved in heat production and conservation in the nonfebrile rabbit.

The effect of clipping the coat on various reactions of calves to heat

1959 ◽  
Vol 52 (3) ◽  
pp. 380-383 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Evaporative Cooling ◽  
Hot Environment ◽  
Better Than

Ten calves were exposed for 3 hr. to an atmosphere in which the dry-bulb temperature was 40° C. and the wet-bulb temperature 33° C, (a) with their normal coats, and (b) after their coats had been clipped.When clipped the calves tolerated the same hot environment better than they did before they were clipped, as evidenced by significant reductions in skin temperature, rectal temperature, respiratory rate and heart rate, as well as by a lessening of various manifestations of distress.This effect of clipping was thought to be due mainly to an improvement in skin, evaporative cooling.

Heat Strain in Protective Clothing Following Hot-Wet or Hot-Dry Heat Acclimation

1996 ◽  
Vol 21 (2) ◽  
pp. 90-108 ◽  
Author(s):  
Tom M. McLellan ◽  
Yukitoshi Aoyagi
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Protective Clothing ◽  
Intermittent Exercise ◽  
Sweat Rate ◽  
Heat Acclimation ◽  
Heat Strain ◽  
Mean Skin Temperature ◽  
Time Required

The purpose of the present study was to compare the heat strain while wearing nuclear, biological, and chemical (NBC) protective clothing following a hot-wet (HW) or hot-dry (HD) heat acclimation protocol. Twenty-two males were assigned to groups HW (n = 7), HD (n = 8), or control (C, n = 7). Subjects were evaluated during continuous treadmill walking while wearing lightweight combat clothing and during intermittent exercise while wearing the NBC protective clothing. While wearing Combat clothing, greater decreases in rectal temperature (Tre), mean skin temperature [Formula: see text], and heart rate were observed for both acclimation groups. For the NBC clothing trials, lower Tre, [Formula: see text], and heart rates were observed only for group HW. The time required for Tre to increase 1.0 °C and 1.5 °C was significantly delayed for groups HW and HD. Sweat evaporation increased for HW, whereas no change was found for HD. The most significant changes in Tre, [Formula: see text], and heart rate while wearing the NBC protective clothing occur following heat acclimation that involves wearing the clothing during exercise. Key words: rectal temperature, mean skin temperature, heart rate, sweat rate

Effects of adrenaline and noradrenaline on the heat production of warm- and cold-acclimated sheep

1981 ◽  
Vol 59 (9) ◽  
pp. 985-993 ◽  
Author(s):  
A. D. Graham ◽  
R. J. Christopherson
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Dose Rate ◽  
Respiration Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Gas Analysis ◽  
Dose Rates ◽  
Temperature Responses

The heat production (HP), heart rate (HR), respiration rate, rumen motility, and body temperature responses to 2.5-h adrenaline (A) and noradrenaline (NA) intrajugular infusions at 0.00, 0.15, 0.30, 0.60, and 0.90 μg∙kg−1∙min−1 were studied in 10 shorn wethers which had been chronically (3–8 weeks) exposed to warm (19–24 °C) or moderately cold (8–13 °C) temperatures. Heat production, as estimated from respired gas analysis, increased 40–45% with all doses of A and the effect was potentiated by chronic cold exposure. Only the higher dose rates of NA induced an increase in HP. The maximum HP increase due to NA was 30% and the effect was not influenced by chronic cold exposure. Thermoneutral HP was greater by 16–19% in cold-acclimated as compared with warm-acclimated sheep. Corresponding to the HP effects of A and NA, all doses of A and the highest dose of NA resulted in slight increases in rectal temperature. Respiration rate increased with increased dose rate of NA but only the highest dose of A resulted in an increase in respiration rate. HR, rectal temperature, and respiration rate responses to A and NA were not influenced by cold acclimation.

scholarly journals Oxytocin Regimens for Labour Augmentation and Its Effect on Perinatal Outcomes: A Narrative Review

2021 ◽  
pp. 689-693
Author(s):  
Neema Acharya ◽  
Priyanka Singh ◽  
Monisha Singh ◽  
Priyanjali Sinha
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Adverse Effects ◽  
Fetal Heart Rate ◽  
Fetal Heart ◽  
High Dose ◽  
Main Role ◽  
Safe Delivery ◽  
Delivery Practices ◽  
High Doses

Background: The issue of childbirth, stimulation of labor is very important for successful childbirth and the birth of healthy babies. Obstetricians play main role in providing and rising Maternal and Child Health (MCH) care facilities. One amongst the goal of MCH care is safe delivery with smart feto-maternal outcome. The hormone plays vital role to cut back rates of caesarean birth once used for management of dystocia. Interventions with oxytocin particularly at high doses would lead to adverse effects on fetal heart rate and uterine tachsystole which occurs due to reduction in blood flow during contraction in intervillousspaces. The purpose of use of oxytocin is for physiological birth and for successful delivery practices. For augmentation of labour hormone regimens are low-dose (1-3 milli units/min) and high dose (4-7 milli units/min). Studies have shown high-dose of hormone causes hyperstimulation to womb. It's been mentioned that there's decrease in induction to delivery time at meta-analysis. Augmentation of labour is that the method of accelerating the frequency of contractions to facilitate a labour. The principal methodology for achieving augmentation of labour varies in the use and approach. Oxytocin is widely used for each induction and augmentation of labour. Interventions with oxytocin particularly at high doses would lead to adverse effects on fetal heart rate and uterine tachsystole which occurs due to reduction in blood flow during contraction in intervillous spaces. The purpose of use of oxytocin is for physiological birth and for successful delivery practices. These results reinforce the need to reflect on a change in care during delivery. Thus,this will help health care professional for better understanding on use and its effect during labour which will help in proper decision making for augmentation of labour.

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