Verapamil-induced vasodilator response is enhanced in essential hypertension

Forearm blood flow response to the calcium channel inhibitor verapamil, 1 75 micrograms/100 ml tissue, as measured by venous occlusion plethysmography, was found to be significantly greater in 11 patients with essential hypertension as compared to 11 age-matched normotensive subjects whereas there was no significant difference in increase in forearm blood flow between both groups to non-specific vasodilatation with sodium nitroprusside (1.2 micrograms/100 ml tissue). The increase in forearm blood flow to verapamil correlated positively with basal plasma epinephrine concentration in hypertensives. These findings support the concept of an increased dependency of arteriolar tone on calcium influx in patients with essential hypertension, an abnormally related to the activity of the sympathetic nervous system.