Circulatory effects of stress in essential hypertension.

Abstract

Hemodynamics and plasma catecholamines were studied during mental arithmetics and cold pressor test in thirteen patients with essential hypertension. Blood pressure was significantly increased by both forms of "stress". Cold pressor test caused a significant increase in total peripheral resistance, while mental arithmetics increased heart rate and cardiac output significantly. Thus, different forms of "stress" can increase blood pressure by totally different hemodynamic mechanisms. Acute cardioselective and non-selective beta-receptor blockade did not affect the hemodynamic reaction pattern during cold pressor test. The increase in heart rate and cardiac output during mental arithmetics was blocked by non-selective but not with cardioselective beta-blockade. Both beta-blockers were, however, inefficient in preventing the blood pressure elevation induced by mental arithmetics. Plasma noradrenalin was significantly increased during mental arithmetics after both cardioselective and non-selective beta-blockade compared to placebo. During cold pressor test there was a significant increase in noradrenalin only after non-selective beta-blockade. Adrenalin in plasma was significantly increased only during mental arithmetics after cardioselective beta-blockade. The pathogenesis of essential hypertension is complex and still not fully understood. Both hereditary (1) and environmental factors such as salt intake (2) and stress (3,4,5) are probably of importance as risk factors for essential hypertension. Animal studies have shown that different forms of stress can produce permanent hypertension due to structural changes in the resistance vessels (6). Against this background we decided to investigate acute hemodynamic effects of two well-defined types of "stress", e.g. mental arithmetics and cold pressor test in patients with essential hypertension and to study if the hemodynamic reactions could be modified by cardioselective and non-selective beta-receptor blockade. Catecholamines in plasma were studied before, during and after "stress".