Haemodynamic effects of alpha-receptor blockade during acute administration and chronic treatment

Acute administration of relatively large doses of the postsynaptic alpha-adrenoceptor blocking agent prazosin results in a marked vasodilatation and blood-pressure reduction, often combined with tachycardia. Chronic administration results in a decrease in total peripheral resistance and blood pressure at rest and during exercise. Cardiac output is unchanged at rest but shows a slight increase during exercise. Peripheral blood flow is increased during chronic treatment. It is concluded that alpha-receptor antagonists may be able to normalize - completely or partly - the pathological haemodynamics of the hypertensive patient.