The effect of exercise on intra-arterial blood pressure and pulse rate before and during long-term high-dose treatment with labetalol in patients with severe, therapy-resistant hypertension.

Intra-arterial blood pressure (BP) and pulse rate were measured before, during and after submaximum exercise in 15 patients with severe, therapy-resistant hypertension. Measurements were performed at the start of treatment with labetalol and were repeated after three and six months of therapy. Thirteen patients were examined twice and 11 patients three times. The average daily dose of labetalol was 2185 mg (range 600-4200 mg) after three months and 3036 mg (range 800-6000 mg) after six months. At rest, there were no significant changes in BP or pulse rate in the three investigations. During exercise, a significantly lower increase in both systolic and diastolic BP-but not in pulse rate-was found six months after starting treatment with labetalol. After six months of treatment with labetalol a correlation was found between the labetalol dose and changes in BP.