Haemodynamic Responses to Static and Dynamic Handgrip before and after Autonomic Blockade

Abstract

1. Six healthy men performed static and dynamic handgrip to local muscular fatigue in approximately 6 min under control conditions, i.e. without drugs and after combined para-sympathetic and β-adrenergic blockade with atropine and metoprolol. 2. From rest to exercise at fatigue, systolic, diastolic and mean arterial pressures increased by 32 ± 4 and 39 ± 3 mmHg, 24 ± 3 and 26 ± 4 mmHg, and 26 ± 3 and 30 ± 3 mmHg respectively for static and dynamic handgrip. There were no significant differences between the pressor responses for the two modes of contraction. Cardiac output increased significantly only during dynamic exercise. Total peripheral resistance increased by 2.3 ± 1.0 units for static handgrip (P < 0.05) and by 0.7 ± 0.8 unit (P > 0.05) for dynamic handgrip. Autonomic blockade abolished the heart rate response to both static and dynamic handgrip. For both modes of contraction the systolic arterial pressure responses were 9–12 mmHg lower (P < 0.05) after autonomic blockade, but the diastolic and mean pressure responses were not significantly affected. A significant increase in cardiac output persisted during dynamic exercise. The increase in peripheral resistance during static exercise tended to be greater after blockade. Plasma noradrenaline and adrenaline levels showed only minor elevations in response to static and dynamic handgrip and were not changed by autonomic blockade. 3. These data indicate that when performed to a common end-point with identical small muscle groups static and dynamic exercise produce an equally large pressor response, which is only slightly attenuated by autonomic blockade.