Thermoregulatory reflexes and cutaneous active vasodilation during heat stress in hypertensive humans
| Autor: | Grazia Stagni, S. R. Morris, Dean L. Kellogg, Alexander M. M. Shepherd, Y. Liu, S. B. Rodriguez, Matthias Grossmann |
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| Rok vydání: | 1998 |
| Předmět: |
Male
Mean arterial pressure Physiology Physical exercise Vasodilation Heat Stress Disorders FEV1/FVC ratio Forearm Physiology (medical) Reflex Laser-Doppler Flowmetry medicine Humans Plethysmograph Exercise Skin business.industry Hemodynamics Middle Aged medicine.anatomical_structure Regional Blood Flow Vasoconstriction Bretylium Tosylate Anesthesia Hypertension Sympatholytics Female medicine.symptom business Body Temperature Regulation |
| Zdroj: | Journal of Applied Physiology. 85:175-180 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/jappl.1998.85.1.175 |
| Popis: | During dynamic exercise in the heat, increases in skin blood flow are attenuated in hypertensive subjects when compared with normotensive subjects. We studied responses to passive heat stress (water-perfused suits) in eight hypertensive and eight normotensive subjects. Forearm blood flow was measured by venous-occlusion plethysmography, mean arterial pressure (MAP) was measured by Finapres, and forearm vascular conductance (FVC) was calculated. Bretylium tosylate (BT) iontophoresis was used to block active vasoconstriction in a small area of skin. Skin blood flow was indexed by laser-Doppler flowmetry at BT-treated and untreated sites, and cutaneous vascular conductance was calculated. In normothermia, FVC was lower in hypertensive than in normotensive subjects ( P < 0.01). During heat stress, FVC rose to similar levels in both groups ( P > 0.80); concurrent cutaneous vascular conductance increases were unaffected by BT treatment ( P > 0.60). MAP was greater in hypertensive than in normotensive subjects during normothermia ( P < 0.05, hypertensive vs. normotensive subjects). During hyperthermia, MAP fell in hypertensive subjects but showed no statistically significant change in normotensive subjects ( P < 0.05, hypertensive vs. normotensive subjects). The internal temperature at which vasodilation began did not differ between groups ( P> 0.80). FVC is reduced during normothermia in unmedicated hypertensive subjects; however, they respond to passive heat stress in a fashion no different from normotensive subjects. |
| Databáze: | OpenAIRE |
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