Sympathetic nervous system response to graded exercise: Effect of beta-blockade

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Journal Article

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Beta-blockade; Essential hypertension; Exerdse; Plasma catecholamines; Sympathetic nervous system


This study compares the sympathetic nervous system response to graded exercise in normotensire and essential hypertensire subjects with and without beta-adrenergic blockade. Blood pressure (BP), heart rate, and plasma norepinephrine (NE), epinephrine (E), and dopamine (DA) were measured just before starting the exercise (Pre-Ex), in the submaximal exercise (Sub-max), and after 8 minutes rest (Post-Ex). On placebo, Sub-max induced in both normotensires and hypertensives a similar increase in NE and E plasma levels. Plasma DA remained unchanged. Propranolol in controls and propranolol or mepindolol ij hypertensives didn't modify significantly: 1) Pre-Ex plasma levels of E, NE, and DA; 2) response at Sub-max in controls; 3) plasma E and DA in hypertensive patients. In hypertensives on beta-blockade, submaximal exercise elicited a greater increase in plasma NE. Values for plasma NE in patients on propranolol were 1135 ± 229 pg/ml higher than those obtained in the same patients on placebo (p < 0.001). On mepindolol, the plasma NE increment was higher than that on placebo (p < 0.05), but lower than that on propranolol (p < 0.01). In controls, propranolol did not significantly modify BP at Pre-Ex or its response to exercise, whereas systolic and diastolic BP were significantly lower at Pre-Ex, Sub-max, and Post-Ex in hypertensives. On beta-blockade, heart rate decrease in Pre-Ex, Sub-max, and Post-Ex were not different in controls and hypertensives. The differences found on beta blockade would indicate that the effects of beta blockers are not identical in normotensive and hypertensive subjects. © 1981 American Heart Association, Inc.