Effects of nifedipine and verapamil on isometric and dynamic exercise in normal subjects

Effects of single- and multiple-dose nifedipine and verapamil in 10 healthy men were compared with the effect of placebo during static and dynamic physical activity. Blood pressure (BP), heart rate (HR), and plasma catecholamine and plasma potassium levels were assessed and quantified at rest and at peak levels of 50% handgrip and at rest and peak treadmill activity during placebo, single- and at 2 multiple-dose levels of each of the drugs. Peak BP responses were blunted by a maximal dosage of 120 mg of verapamil administered twice daily during static activity. No blunting of HR response was observed. BP and HR did not change significantly at any dosage level of nifedipine during static exercise. During isotonic exercise the only significant alteration was a progressive decrease in the peak exercise HR with both verapamil and nifedipine. The plasma potassium level increased with both static and dynamic activity but to no greater level than that seen with placebo. Plasma norepinephrine concentration increased at rest after administration of maximal dosage of nifedipine during both isometric and isotonic phases of the study. This is probably related to the underlying mild to moderate increase in sympathetic tone induced by nifedipine. Overall, the hemodynamic responses to exercise are not blunted with calcium-channel antagonists at the dosages studied.