Changes in plasma norepinephrine concentration and thrombocyte alpha 2-adrenoceptor density during long-term...

Antihypertensive drugs influence the sympathetic nervous system in different ways that may cause adverse or beneficial effects. We treated 48 hypertensive patients with either nitrendipine (10-20 mg twice daily, b.i.d.) or captopril (25-50 mg b.i.d.) for 16 weeks to evaluate changes in plasma catecholamines, platelet alpha 2- and lymphocyte beta 2-adrenoceptors. Blood pressure (BP) decreased from 153/95 to 135/87 mm Hg with captopril and from 155/99 to 137/89 mm Hg with nitrendipine. Treatment with nitrendipine significantly stimulated plasma norepinephrine (NE) from 327 +/- 37 to 446 +/- 50 pg/ml, and treatment with captopril resulted in a significant reduction in platelet alpha 2-adrenoceptor density from 265 +/- 39 to 171 +/- 26 fmol/mg protein. Despite having equal BP-lowering properties, captopril and nitrendipine have different effects on the sympathetic nervous system. Stimulation of plasma NE during long-term treatment with nitrendipine may contribute to possible adverse effects, whereas reduction in alpha 2-adrenoceptors induced by captopril may contribute to the vasodilating effect of angiotensin-converting enzyme (ACE) inhibition.