Blood pressure reduction and vascular adaptation. A study on long-term effects of treatment with mefruside or atenolol.

Systemic BP reduction, calf blood flow and vascular resistance in the calf were determined in forty-two previously untreated patients with mild to moderate essential hypertension (WHO I-WHO II) before and after 6 weeks, 6 months and 18 months of BP-lowering treatment with mefruside (25 mg daily) or atenolol (100--400 mg daily). Blood flow was determined with venous occlusion plethysmography using a mercury-in-rubber strain gauge technique in the supine patient. Auscultatory BP was measured on the right arm simultaneously with the flow determinations and resistance was calculated from the flow and pressure. BP was reduced significantly and to the same extent by the two drugs. In the atenolol group a rise in resting resistance and a corresponding fall in resting blood flow was seen initially. These changes were entirely normalized during continued treatment for 18 months. In the mefruside group no significant haemodynamic changes during treatment were observed at rest apart from the BP fall. None of the drugs reduced resistance at "maximal" vasodilatation, indicating that no regress of the hypertensive structural changes of the calf blood vessels had taken place.