Six essential hypertensive (resting mean arterial pressure, MAP > 110 mm Hg) and eight normotensive (resting MAP < 95 mm Hg) men, aged 30-58 yr, were tested during 1 h of dynamic leg exercise in the heat. Environmental conditions were fixed at 38 °C dry-bulb temperature and 28 °C wet-bulb temperature; exercise intensity was preset to approximate 40% of each subject's maximal aerobic capacity (actual range 38-43%). Forearm blood flow (FBF) was measured by impedance plethysmography. The intergroup difference in arterial pressure was maintained but not increased or decreased during exercise in the heat. FBF increased in both groups, but the increase was significantly less for the hypertensive subjects. FBF showed a significant linear correlation (different from 0) with core temperature in seven of eight control subjects but in none of the hypertensive subjects. The magnitude of FBF increase was inversely proportional to resting MAP (r = -0.89). It was concluded that essential hypertensive subjects respond to exercise in the heat with a diminished FBF response related to an alteration in control relative to central (core temperature) influences. This may be due to an imbalance between thermal and nonthermal (baroreflex) mechanisms controlling cutaneous blood flow.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Applied Physiology Respiratory Environmental and Exercise Physiology|
|State||Published - Jan 1 1984|
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