Homeostasisin animals (Sus domesticus) during exposure to a warm environment.

This investigation determined the effect of different rates of dehydration, induced by ingesting different volumes of fluid during prolonged exercise, on hyperthermia, heart rate (HR), and stroke volume (SV). On four different occasions, eight endurance-trained cyclists [age 23 +/- 3 (SD) yr, body wt 71.9 +/- 11.6 kg, maximal O2 consumption 4.72 +/- 0.33 l/min] cycled at a power output equal to 62-67% maximal O2 consumption for 2 h in a warm environment (33 degrees C dry bulb, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or ingested a small (SF), moderate (MF), or large (LF) volume of fluid that replaced 20 +/- 1, 48 +/- 1, and 81 +/- 2%, respectively, of the fluid lost in sweat during exercise. The protocol resulted in graded magnitudes of dehydration as body weight declined 4.2 +/- 0.1, 3.4 +/- 0.1, 2.3 +/- 0.1, and 1.1 +/- 0.1%, respectively, during NF, SF, MF, and LF. After 2 h of exercise, esophageal temperature (Tes), HR, and SV were significantly different among the four trials (P < 0.05), with the exception of NF and SF. The magnitude of dehydration accrued after 2 h of exercise in the four trials was linearly related with the increase in Tes (r = 0.98, P < 0.02), the increase in HR (r = 0.99, P < 0.01), and the decline in SV (r = 0.99, P < 0.01). LF attenuated hyperthermia, apparently because of higher skin blood flow, inasmuch as forearm blood flow was 20–22% higher than during SF and NF at 105 min (P < 0.05). There were no differences in sweat rate among the four trials. In each subject, the increase in Tes from 20 to 120 min of exercise was highly correlated to the increase in serum osmolality (r = 0.81-0.98, P < 0.02-0.19) and the increase in serum sodium concentration (r = 0.87-0.99, P < 0.01-0.13) from 5 to 120 min of exercise. In summary, the magnitude of increase in core temperature and HR and the decline in SV are graded in proportion to the amount of dehydration accrued during exercise.

Download Full-text

Effect of the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment

Journal of Thermal Biology ◽

10.1016/j.jtherbio.2017.01.010 ◽

2017 ◽

Vol 65 ◽

pp. 26-31 ◽

Cited By ~ 7

Author(s):

Keisuke Takeshima ◽

Sumire Onitsuka ◽

Zheng Xinyan ◽

Hiroshi Hasegawa

Keyword(s):

Exercise Capacity ◽

Endurance Exercise ◽

Ice Slurry ◽

Warm Environment

Download Full-text

Interaction of central and peripheral factors in physiological temperature regulation

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1961.200.3.572 ◽

1961 ◽

Vol 200 (3) ◽

pp. 572-580 ◽

Cited By ~ 55

Author(s):

M. M. Fusco ◽

J. D. Hardy ◽

H. T. Hammel

Keyword(s):

Heat Loss ◽

Core Temperature ◽

Heat Production ◽

Temperature Regulation ◽

Physiological Temperature ◽

Warm Environment ◽

Quantitative Estimates ◽

Cool Environment ◽

Localized Heating ◽

Environmental Temperatures

To evaluate the relative importance of central and peripheral factors in physiological temperature regulation, calorimetric measurements of thermal and metabolic responses in the unanesthetized dog to localized heating of the supraoptic and preoptic regions were made at various environmental temperatures. At all temperatures, heating the hypothalamus caused an imbalance in the over-all heat exchange, and lowered core temperature by 0.8°–1.0°C. In a neutral environment, this was effected by a 30–40% depression of the resting rate of heat production. In a cool environment, heating inhibited shivering so that heat production, relative to heat loss, was low. In a warm environment, vigorous panting and vasodilatation were elicited, thereby increasing heat loss. On cessation of heating, shivering occurred in response to the lowered core temperature, but differed in intensity depending upon the peripheral thermal drive. Reapplication of heating suppressed shivering in all cases. From these data some quantitative estimates were made of the sensitivity of the hypothalamic thermoregulatory ‘centers’, and of the interaction and relative contributions of central and peripheral control.

Download Full-text

Rates and drivers of Red Sea plankton community metabolism

10.5194/bg-2018-487 ◽

2018 ◽

Author(s):

Daffne C. López-Sandoval ◽

Katherine Rowe ◽

Paloma Carillo-de-Albonoz ◽

Carlos M. Duarte ◽

Susana Agusti

Keyword(s):

Red Sea ◽

Gross Primary Production ◽

Environmental Drivers ◽

Community Respiration ◽

Net Community Production ◽

Chl A ◽

Warm Environment ◽

Increasing Temperature ◽

Community Production ◽

Planktonic Communities

Abstract. Resolving the environmental drivers shaping planktonic communities is fundamental to understanding their variability, present and future, across the ocean. More specifically, resolving the temperature-dependence of planktonic communities in low productive waters is essential to predict the response of marine ecosystems to warming scenarios, as ocean warming leads to oligotrophication of the subtropical ocean. Here we quantified plankton metabolic rates along the Red Sea, a unique oligotrophic and warm environment, and analysed the drivers that regulate gross primary production (GPP), community respiration (CR) and the net community production (NCP). The study was conducted on six oceanographic surveys following a north-south transect along Saudi Arabian coasts. Our findings revealed that Chl-a specific GPP and CR rates increased with increasing temperature (R2 = 0.41 and 0.19, respectively, P

Download Full-text

Macroscopic analysis of dental and periodontal tissues of pig (Sus domesticus) exposed to high temperatures

Revista Estomatología ◽

10.25100/re.v21i1.5755 ◽

2017 ◽

Vol 21 (1) ◽

pp. 28-34

Author(s):

Sebastián Medina ◽

Sandra Henao ◽

Viviana Muñóz ◽

Carolina López ◽

Juan Esteban Gutiérrez ◽

...

Keyword(s):

High Temperatures ◽

Alveolar Bone ◽

Great Resistance ◽

Dental Identification ◽

Color Changes ◽

Dental Tissues ◽

Periodontal Tissues ◽

Sus Domesticus ◽

Physical Changes ◽

Macroscopic Analysis

SUMMARYObjective: To describe the physical changesofmacro-structural dental tissues (enamel,dentin and cement) and periodontal(oral mucous membrane, alveolar compactbone and cancellous alveolar bone) ofdomestic pig (Sus domesticus) expose tohigh temperatures.Materials and methods: This descriptivestudy observed the physical changes in macro-structural dental tissues and periodontalin 25 teeth of domestic pigs subjected tohigh temperatures (200°C, 400°C, 600°C,800°C and 1000°C).Results: Dental and periodontal tissues studiedshow great resistance when subjectedto high temperatures without changing significantlytheir macro-structure. At 200°Cno color changes and cracks appear in theenamel. At 400°C there was an increase ofthe fissure and no separation between thehard tissues, initiating carbonization. At600°C fractures in the dental tissues andbone are most apparent. At 800°C burningof the tissues initiated. At 1000°C there wasno evidence of soft tissue.Conclusions: Macroscopic analysis of theteeth articulated in their alveolar-dentalunits constitutes a experimental model thatssimulates the changes of dental and periodontaltissues expose to high temperature.It is recommended to conduct astudy onhuman teeth in their respective unit articulatedalveolar to determine whether themacro-structural physical changes describedare repeated and can be extrapolated,and which can eventually be used duringthe process of dental identification anddocumentation of the medical legal autopsyused in the case of bodies or human remainsburned, charred and burned.Key words: Forensic dentistry, domesticpig (Sus domesticus), dental and periodontaltissues, temperature exposition, animalmodel.

Download Full-text