Thermoregulatory responses in the rat to exercise in the heat following prolonged heat exposure

1982 ◽  
Vol 52 (3) ◽  
pp. 734-738 ◽  
Author(s):  
R. Francesconi ◽  
R. Hubbard ◽  
M. Mager
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Thermal Stress ◽  
Prolonged Exposure ◽  
Evaporative Cooling ◽  
Heat Exposure ◽  
Endurance Capacity ◽  
Significant Decrement ◽  
Body Weights ◽  
Prolonged Heat

To determine the effects of prolonged exposure to severe thermal stress on the subsequent ability to exercise in the heat, rats were exposed to a hot (35 degrees C) environment for 1, 2, 3, or 4 wk. At each of these weekly intervals the rats ran on a treadmill to hyperthermic exhaustion (41.5--43.0 degrees C), and tail-skin (Tt-sk) and rectal (Tre) temperatures were monitored. The results indicated that prolonged heat exposure did not enhance the rats' endurance capacity. Further, as the period of heat stress increased, there was a concomitant significant decrement in tail-skin vasodilation; indeed, after 3 and 4 wk at 35 degrees C Tt-sk reflects a complete shutdown of blood flow to the tail during exercise. Additionally, slight evaporative cooling from exogenous fluid (saliva or urine from the treadmill surface) might account for the low Tt-sk in relation to Tre and Ta. Hematocrit ratios ordinarily decreased from week to week during heat exposure, whereas body weights remained very consistent throughout the 4-wk interval. The mechanism of this decrement in vasodilation is undergoing further study.

The role of the mammary gland during heat stress

2019 ◽  
Author(s):  
◽  
Ricardo Oliveira Rodrigues
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Mammary Gland ◽  
Dairy Cows ◽  
Prolonged Exposure ◽  
Transcriptional Profiling ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
University Of Missouri ◽  
Lactating Dairy Cows

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Disruptive effects of climate change, such as increasing environmental temperature, have direct impacts on economic viability and efficiency of food production. In lactating dairy cows, heat stress reduces milk production and alters function of mammary secretory cells, at least partly by disturbing local protein metabolism. We hypothesized that hyperthermia would not only reduce mammary blood flow but would also reduce mammary extraction of nutrients from blood. In addition, we hypothesized that transcriptional profiling of mammary tissue would reveal disruption of cellular homeostasis. Our objective was to determine the effects of hyperthermia on mammary function. More specifically, we aimed to profile mammary blood flow and the changes in mammary transcriptome of heat-stressed lactating dairy cows. We investigated the effects of early and prolonged exposure of lactating dairy cows to hyperthermia by exposing cows to programmed constantly elevated temperature and humidity to induce and maintain body temperature approximately 1[degree]C above normal. Experiments were conducted to evaluate the production responses of hyperthermic lactating dairy cows, to characterize total and nutritive mammary blood flow, and to elucidate the regulation of mammary function during early and prolonged exposure to hyperthermia. Results from these studies established that 1) hyperthermia reduces total and nutritive mammary blood flow, limiting nutrient disappearance across the mammary gland; 2) hyperthermia does not induce shunting of blood away from the gland; 3) hyperthermia affects mammary tissue transcriptome, mainly altering processes associated with ECM and cell adhesion; 4) the effects of exposure to prolonged heat stress on mammary gene expression are distinct from the effects of feed restriction, in lactating dairy cows; and 5) mammary function is reestablished within 8 days after cessation of heat stress.

Physiological involvement of placental endothelin-1 and prostaglandin F2α in uteroplacental circulatory disturbance in pregnant rats exposed to heat stress

2004 ◽  
Vol 82 (4) ◽  
pp. 225-230 ◽  
Author(s):  
Hiroyuki Nakamura ◽  
Ichiyo Matsuzaki ◽  
Kotaro Hatta ◽  
Keiki Ogino
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Heat Exposure ◽  
Prostaglandin F2α ◽  
Endothelin Receptor ◽  
Pregnant Rats ◽  
Pregnancy Failure ◽  
Circulatory Disturbance ◽  
Uteroplacental Blood Flow ◽  
Circulatory Disturbances

Several studies suggest that heat stress affects placental functions including uteroplacental circulation, subsequently leading to pregnancy failure and birth weight reduction. To clarify the involvement of endothelin and placental prostaglandin (PG) systems in the uteroplacental circulation during heat stress, we examined the effects of i.v. administration of the endothelin receptor antagonist bosentan and the cyclooxygenase inhibitor indomethacin on uteroplacental blood flow and on placental PGE2 and PGF2α levels and their 13,14-dyhydro-15-keto-metabolites (PGEM and PGFM, respectively) in heat-exposed or non-heat-exposed pregnant rats. The administration of bosentan or indomethacin did not change uteroplacental blood flow in non-heat-exposed pregnant rats. In contrast, heat reduced uteroplacental blood flow in pregnant rats, but the reduction was reversed by the administration of bosentan or indomethacin before heat exposure. Heat did not change placental PGE2 or PGEM levels, but in pregnant rats it increased placental PGF2α and PGFM levels, which were reversed by bosentan or indomethacin. Our results suggest that the activation of placental endothelin receptor and PGF2α systems are involved in the uteroplacental circulatory disturbances produced by heat. PGF2α systems activated by heat may be involved in the vasoconstricting effects of endothelin-A and -B receptors during heat exposure.Key words: blood flow, endothelin, placenta, pregnancy, prostaglandin.

Effects of exercise and heat stress on regional blood flow in pregnant sheep

1986 ◽  
Vol 60 (5) ◽  
pp. 1759-1764 ◽  
Author(s):  
A. W. Bell ◽  
J. R. Hales ◽  
A. A. Fawcett ◽  
R. B. King
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Heat Stress ◽  
Regional Blood Flow ◽  
Heat Exposure ◽  
Respiratory Muscles ◽  
Fold Increase ◽  
Pregnant Uterus ◽  
Pregnant Sheep ◽  
Exercise Induced

Radioactive microspheres were used to measure cardiac output and blood flow to most major tissues, including those in the pregnant uterus, in late-pregnant ewes at rest and during treadmill exercise (approximately 3-fold increase in metabolic rate for 30 min) in thermoneutral (TN) (dry bulb temperature (Tdb) = 13 degrees C, wet bulb temperature (Twb) = 10 degrees C) and mildly hot (MH) (Tdb = 40 degrees C, Twb = 27 degrees C) environments. Exercise caused major increases in blood flow to respiratory muscles, nonrespiratory limb muscles, and adipose tissue, and flow was decreased to some gastrointestinal tissues, spleen, pancreas, and to placental and nonplacental tissues in the pregnant uterus. Heat exposure had relatively little effect on these exercise-induced changes, except that flow was further increased in the respiratory muscles. Results are compared with those of a similar study on nonpregnant sheep in which changes in muscle, skin, and visceral flows during exercise were attenuated by heat exposure. It is suggested that redistribution of blood flow from the pregnant uterus, which in resting ewes took 22% of cardiac output, is a significant buffer against the potentially deleterious effects of combined exercise and heat stress on blood flow to exercising muscles and thermoregulatory tissues.

scholarly journals Gene and Metabolite Integration Analysis through Transcriptome and Metabolome Brings New Insight into Heat Stress Tolerance in Potato (Solanum tuberosum L.)

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 103
Author(s):  
Bailin Liu ◽  
Lingshuang Kong ◽  
Yu Zhang ◽  
Yuncheng Liao
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Elevated Temperatures ◽  
Solanum Tuberosum L ◽  
Heat Exposure ◽  
Differentially Expressed ◽  
Heat Response ◽  
Negative Ionization ◽  
Stress Related Genes ◽  
Prolonged Heat

Potatoes are particularly vulnerable to elevated temperatures, with short heat stress (6 h) inducing stomatal opening and reducing membrane stability and prolonged heat stress (3-day) decreasing the photosynthetic capacity of potato leaves. The integration of transcriptomics and metabolomics methods demonstrated that 448 heat upregulated and 918 heat downregulated genes and 325 and 219 compounds in the positive and negative ionization modes, respectively, were up- or downregulated in leaves in response to short and prolonged heat stress. Differentially expressed genes enriched in photosynthesis, cell wall degradation, heat response, RNA processing, and protein degradation were highly induced during heat exposure, and differentially expressed metabolites involved in amino acid biosynthesis and secondary metabolism were mostly induced during heat exposure, suggesting a possible role of these genes and metabolites in the heat tolerance of the potato. Metabolite and transcript abundances for the upregulation of flavone and flavonol biosynthesis under prolonged heat stress were closely correlated. Heat-induced gene expression in Arabidopsisthaliana shoots and potato leaves overlapped, and heat stress-responsive genes overlapped with drought stress-related genes in potato. The transient expression of four heat-induced genes in Nicotiana benthamiana exhibited increased heat tolerance. This study provides a new transcriptome and metabolic profile of the potato’s response to heat.

Sex differences in blood flow distribution of normothermic and heat-stressed rabbits

1995 ◽  
Vol 268 (1) ◽  
pp. R66-R71 ◽  
Author(s):  
A. Lublin ◽  
D. Wolfenson ◽  
A. Berman
Keyword(s):  
Blood Flow ◽  
Sex Differences ◽  
Heat Stress ◽  
Skeletal Muscles ◽  
Heat Dissipation ◽  
Thermal State ◽  
Heat Exposure ◽  
Flow Distribution ◽  
Males And Females ◽  
Alpha Chloralose

Sex differences in blood flow (BF) distribution of male and female mature laboratory rabbits were determined in normothermic and heat-stressed states. Animals were anesthetized with alpha-chloralose, and BF distribution was determined by radioactive microspheres in the thermoneutral state and then again during hyperthermia after 2 h of heat exposure. Cardiac output did not change in either sex during heat stress. BF to the toe and ear skin and to nasal turbinates was lower in females than in males, whereas that to the diaphragm, sternum, intercostal muscles, spleen, and skeletal muscles was higher in females. A thermal state-by-sex interaction was detected in several organs, indicating that during heat stress in males, BF is significantly higher than in the controls, whereas in females a decline, no change, or only a slight increase was recorded. Males did not exhibit any decrease in inner organ BF during heat stress, whereas females did. Results show sex differences in BF distributions under normothermia and hyperthermia, suggesting that males and females differ in their BF regulation in both peripheral organs, which are active in heat dissipation, and inner body organs.

Application of a Nonlinear Model to Transcript Levels of Upregulated Stress Response Gene ibpA in Stationary-Phase Salmonella enterica Subjected to Sublethal Heat Stress

2016 ◽  
Vol 79 (7) ◽  
pp. 1089-1096 ◽  
Author(s):  
LAURA M. CARROLL ◽  
TERESA M. BERGHOLZ ◽  
IAN M. HILDEBRANDT ◽  
BRADLEY P. MARKS
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Thermal Resistance ◽  
Stationary Phase ◽  
Nonlinear Model ◽  
Thermal Inactivation ◽  
Prolonged Exposure ◽  
Physiological State ◽  
Meat Products ◽  
Transcript Levels

ABSTRACT Sublethal heating, which can occur during slow cooking of meat products, is known to induce increased thermal resistance in Salmonella. However, very few studies have addressed the kinetics of this response. Although several recent studies have reported improved thermal inactivation models that include the effect of prior sublethal history on subsequent thermal resistance, none of these models were based on cellular-level responses to sublethal thermal stress. The goal of this study was to determine whether a nonlinear model could accurately portray the response of Salmonella to heat stress induced by prolonged exposure to sublethal temperatures. To accomplish this, stationary-phase Salmonella Montevideo cultures were subjected to various heating profiles (held at either 40 or 45°C for 0, 5, 10, 15, 30, 60, 90, 180, or 240 min) using a PCR thermal cycler. Differential plating on selective and nonselective media was used to confirm the presence of cellular injury. Reverse transcription quantitative PCR was used to screen the transcript levels of six heat stress–related genes to find candidate genes for nonlinear modeling. Injury was detected in populations of Salmonella held at 45°C for 30, 60, and 90 min and at 40°C for 0, 5, and 90 min (P < 0.05), whereas no significant injury was found at 180 and 240 min (P > 0.05). The transcript levels of ibpA, which codes for a small heat shock protein associated with the ClpB and DnaK-DnaJ-GrpE chaperone systems, showed the greatest increase relative to the transcript levels at 0 min, which was significant at 5, 10, 15, 30, 60, 90, and 180 min at 45°C and at 5, 10, 15, 30, 60, and 90 min at 40°C (P < 0.05). Using ibpA transcript levels as an indicator of adaptation to thermal stress, a nonlinear model for sublethal injury is proposed. The use of variables indicating the physiological state of the pathogen during stress has the potential to increase the accuracy of thermal inactivation models that must account for prolonged exposure to sublethal temperatures.

scholarly journals Spray-Dried Plasma Improves Body Weight, Intestinal Barrier Function, and Tibia Strength during Experimental Constant Heat Stress Conditions

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2213
Author(s):  
Jared Ruff ◽  
Thaina L. Barros ◽  
Joy Campbell ◽  
Ricardo González-Esquerra ◽  
Christine N. Vuong ◽  
...  
Keyword(s):  
Heat Stress ◽  
Intestinal Barrier ◽  
Fluorescein Isothiocyanate ◽  
Serum Levels ◽  
Negative Control ◽  
Intestinal Barrier Function ◽  
Negative Consequences ◽  
Fluorescein Isothiocyanate Dextran ◽  
Prolonged Heat ◽  
Spray Dried

The aim of this study was to see how spray-dried plasma (SDP) supplementation affected broiler chicken performance, intestinal permeability, and bone strength during persistent heat stress. One-day-old chicks (n = 480) were randomly assigned into twelve environmental corrals; four thermoneutral (TN-negative control, maintained at 24 °C from d 21–42); four heat stress (HS, exposed to 35 °C from d 21–42); and four heat stress treated with 2% SDP in the feed until d 28 followed by 1% SDP until d 42 (HS-SDP). The performance and serum levels of fluorescein isothiocyanate-dextran (FITC-d) were evaluated at d 21, 28, 35, and 42. The tibias strength was evaluated on d 21 and 42. The increment in chicken temperature (p < 0.05) was observed two h following the increase in environmental temperature in both HS groups and was associated with decreased performance parameters compared with the TN group. At d 42 of age, the chickens exposed to HS had an impaired gut permeability and decreased tibia strength compared to the TN group (p < 0.05). However, partially feeding SDP mitigated these adverse effects significantly. These findings imply that using SDP strategically during stressful times, such as prolonged heat stress, may help mitigate its negative consequences.

scholarly journals Experiments on Energy-Efficient Evaporative Cooling Systems for Poultry Farm Application in Multan (Pakistan)

2021 ◽  
Vol 13 (5) ◽  
pp. 2836
Author(s):  
Khawar Shahzad ◽  
Muhammad Sultan ◽  
Muhammad Bilal ◽  
Hadeed Ashraf ◽  
Muhammad Farooq ◽  
...  
Keyword(s):  
Heat Stress ◽  
Low Cost ◽  
Evaporative Cooling ◽  
Thermal Exposure ◽  
Climatic Conditions ◽  
The Body ◽  
Dew Point ◽  
Sweat Glands ◽  
Cooling Systems ◽  
Humidity Index

Poultry are one of the most vulnerable species of its kind once the temperature-humidity nexus is explored. This is so because the broilers lack sweat glands as compared to humans and undergo panting process to mitigate their latent heat (moisture produced in the body) in the air. As a result, moisture production inside poultry house needs to be maintained to avoid any serious health and welfare complications. Several strategies such as compressor-based air-conditioning systems have been implemented worldwide to attenuate the heat stress in poultry, but these are not economical. Therefore, this study focuses on the development of low-cost and environmentally friendly improved evaporative cooling systems (DEC, IEC, MEC) from the viewpoint of heat stress in poultry houses. Thermodynamic analysis of these systems was carried out for the climatic conditions of Multan, Pakistan. The results appreciably controlled the environmental conditions which showed that for the months of April, May, and June, the decrease in temperature by direct evaporative cooling (DEC), indirect evaporative cooling (IEC), and Maisotsenko-Cycle evaporative cooling (MEC) systems is 7–10 °C, 5–6.5 °C, and 9.5–12 °C, respectively. In case of July, August, and September, the decrease in temperature by DEC, IEC, and MEC systems is 5.5–7 °C, 3.5–4.5 °C, and 7–7.5 °C, respectively. In addition, drop in temperature-humidity index (THI) values by DEC, IEC, and MEC is 3.5–9 °C, 3–7 °C, and 5.5–10 °C, respectively for all months. Optimum temperature and relative humidity conditions are determined for poultry birds and thereby, systems’ performance is thermodynamically evaluated for poultry farms from the viewpoint of THI, temperature-humidity-velocity index (THVI), and thermal exposure time (ET). From the analysis, it is concluded that MEC system performed relatively better than others due to its ability of dew-point cooling and achieved THI threshold limit with reasonable temperature and humidity indexes.

scholarly journals Heat Stress and Goat Welfare: Adaptation and Production Considerations

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1021
Author(s):  
Veerasamy Sejian ◽  
Mullakkalparambil V. Silpa ◽  
Mini R. Reshma Nair ◽  
Chinnasamy Devaraj ◽  
Govindan Krishnan ◽  
...  
Keyword(s):  
Heat Stress ◽  
Body Condition Score ◽  
Heat Exposure ◽  
Stocking Density ◽  
Production Performance ◽  
Farm Animals ◽  
Meat Production ◽  
Important Species ◽  
Tropical Regions ◽  
Tropical Climates

This review attempted to collate and synthesize information on goat welfare and production constraints during heat stress exposure. Among the farm animals, goats arguably are considered the best-suited animals to survive in tropical climates. Heat stress was found to negatively influence growth, milk and meat production and compromised the immune response, thereby significantly reducing goats’ welfare under extensive conditions and transportation. Although considered extremely adapted to tropical climates, their production can be compromised to cope with heat stress. Therefore, information on goat adaptation and production performance during heat exposure could help assess their welfare. Such information would be valuable as the farming communities are often struggling in their efforts to assess animal welfare, especially in tropical regions. Broadly three aspects must be considered to ensure appropriate welfare in goats, and these include (i) housing and environment; (ii) breeding and genetics and (iii) handling and transport. Apart from these, there are a few other negative welfare factors in goat rearing, which differ across the production system being followed. Such negative practices are predominant in extensive systems and include nutritional stress, limited supply of good quality water, climatic extremes, parasitic infestation and lameness, culminating in low production, reproduction and high mortality rates. Broadly two types of methodologies are available to assess welfare in goats in these systems: (i) animal-based measures include behavioral measurements, health and production records and disease symptoms; (ii) resources based and management-based measures include stocking density, manpower, housing conditions and health plans. Goat welfare could be assessed based on several indicators covering behavioral, physical, physiological and productive responses. The important indicators of goat welfare include agonistic behavior, vocalization, skin temperature, body condition score (BCS), hair coat conditions, rectal temperature, respiration rate, heart rate, sweating, reduced growth, reduced milk production and reduced reproductive efficiency. There are also different approaches available by which the welfare of goats could be assessed, such as naturalistic, functional and subjective approaches. Thus, assessing welfare in goats at every production stage is a prerequisite for ensuring appropriate production in this all-important species to guarantee optimum returns to the marginal and subsistence farmers.

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