Abstract
In contrast to beta-adrenoceptor blocking agents, calcium channel blockers do not appear to affect exercise tolerance in hypertensive subjects. A possible explanation is a difference in the metabolic effects of both types of drugs. Therefore, the effects of 4-week treatment periods with verapamil and propranolol on metabolic parameters during an endurance bicycle ergometer test were studied in eight patients with mild to moderate essential hypertension. Patients exercised at a work load which increased the heart rate to 150 bts/min during placebo. A single-blind, placebo-controlled, randomized cross-over design was used. The dose of propranolol and verapamil was adjusted to lower standing diastolic blood pressure < 90 mmHg. Average daily doses were 155±21 mg propranolol and 390±44 mg verapamil.
Exercise heart rate was reduced during propranolol and verapamil (P<0.01), but the reduction was more pronounced during propranolol than during verapamil (P<0.05). Minute ventilation and oxygen consumption were unchanged during propranolol and verapamil. The respiratory exchange ratio tended to increase during propranolol. Plasma glucose and lactate concentrations were unchanged during propranolol and verapamil. In contrast, plasma glycerol and nonesterified fatty acids were reduced during propranolol (P<0.05), but unchanged during verapamil. Plasma potassium levels were increased during propranolol (P<0.05).
Despite the important direct and indirect role of calcium ions in the regulation of many metabolic processes, no effect of verapamil on metabolic parameters during submaximal exercise was found. In contrast, propranolol had an effect on fat and potassium metabolism during exercise.
Key words
calcium channel blocker - beta-adrenoceptor blocker - exercise - metabolism - essential hypertension
