Thermoregulation during prolonged exercise in heat: alterations with beta-adrenergic blockade
| Autor: | H. Peters, Jack H. Wilmore, Joni K. Kalis, G. Feese, S. M. Jilka, J. A. Taylor, Beau J. Freund, Michael J. Joyner, J. Nittolo |
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| Rok vydání: | 1987 |
| Předmět: |
Adult
Male medicine.medical_specialty Hot Temperature Physiology Physical Exertion Cardiovascular System Body Temperature Cardiovascular Physiological Phenomena Placebos Oxygen Consumption Heart Rate Physiology (medical) Internal medicine Receptors Adrenergic beta medicine Humans Cardiac Output Prolonged exercise Cardiovascular drift business.industry Muscles Stroke Volume Thermoregulation Propranolol Beta adrenergic blockade body regions Endocrinology Atenolol Warm environment Regional Blood Flow Anesthesia Arm Vascular Resistance business Body Temperature Regulation |
| Zdroj: | Journal of applied physiology (Bethesda, Md. : 1985). 63(3) |
| ISSN: | 8750-7587 |
| Popis: | Thermoregulation and cardiovascular drift were studied under conditions of prolonged exercise in a warm environment (dry bulb temperature 31.7 +/- 0.3 degrees C, rh 44.7 +/- 4.7%) during beta-adrenergic blockade. Fourteen subjects performed 90-min rides on a cycle ergometer at a work rate equivalent to 40% of their control maximal O2 uptake under each of three treatments provided in a randomized double-blind manner: atenolol (100 mg/day), propranolol (160 mg/day), and a placebo. Exercise during the propranolol trial resulted in significantly higher forearm vascular resistance values and significantly lower forearm blood flows (FBF) compared with the placebo trial. However, the significantly lower FBF during propranolol did not significantly alter the rectal temperature (Tre) response to prolonged exercise. In addition, both beta-blockers produced lower FBF for any given Tre, suggesting that beta-adrenergic blockade affects FBF through nonthermal factors. The slight differences in Tre, despite the large differences in FBF between the various treatments, are apparently the result of an enhanced sweat loss and a lower mean skin temperature during exercise with beta-blockade. The uncoupling of FBF and sweat loss provides evidence of independent regulation. The reduction in FBF at any given Tre was concomitant to lower blood pressure values during beta-blockade and suggests that baroreflexes provide significant input to the control of skin blood flow when both pressure and temperature maintenance are simultaneously challenged. |
| Databáze: | OpenAIRE |
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