Catecholamines in Hypertension and Exercise
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Results of a previous study at Bronson Clinical Investigation Unit (Data, et al. 1978) suggested a greater sensitivity of adrenergic receptors in hypertensive over normotensive subjects. In this study we attempted to investigate this possible sensitivity difference of adrenergic receptors in hypertensives by measuring norepinephrine and epinephrine levels before and after a treadmill exercise (as was done in the previously mentioned study) as well as the levels of various substances whose release in the body is affected by catecholamines. To evaluate the role of the adrenergic nervous system in normotensive and hypertensive blood pressure responses with relation to the type of exercise employed, two additional exercises (a bicycle and single arm exercise) were performed by the same two groups of subjects. While norepinephrine and epinephrine levels significantly increased with all exercises, there was no significant difference in this increase between hypertensives and normotensives, nor was the catecholamine rise related to the type of exercise performed. We could, therefore, not conclude any real difference in the sensitivity of hypertensive and normotensive adrenergic receptors. Furthermore, we could not conclude any significant role of the adrenergic nervous system and resulting blood pressure responses based on the type of exercise employed.