The central and peripheral circulation during and after sodium nitroprusside induced hypotension in the rat.

Central haemodynamics and regional blood flow were investigated during and after sodium nitroprusside (SNP) infusion in halothane anaesthetized rats. The administration of SNP 40 micrograms kg-1 min-1, decreased mean arterial pressure (MAP) to 52 (mean) mm Hg. Cardiac output (CO) remained unchanged, while heart rate (HR) and systemic vascular resistance (SVR) decreased. The regional blood flow in the splanchnic organs increased. When the SNP infusion was discontinued, MAP returned rapidly to, but not above, its initial value. Fifteen minutes later, CO was increased, while SVR and HR remained decreased. Cerebral, myocardial and renal perfusion increased and the changes in the splanchnic area persisted. It is obvious that, although MAP was reversed rapidly upon withdrawal of SNP, central and regional haemodynamic effects were prolonged.