Haemodynamic effects of labetalol-induced hypotension in the anaesthetized dog.

Central haemodynamic changes and regional blood flow were studied using the microsphere technique, during labetalol-induced hypotension in dogs anaesthetized with pentobarbitone and fentanyl. Labetalol 15 mg kg-1 decreased mean arterial pressure from an average of 88 mm Hg to 47 mm Hg. Mean pulmonary arterial pressure was unchanged. Cardiac output was reduced by decrease in stroke volume, while heart rate remained unchanged. Myocardial blood flow decreased approximately in parallel with left ventricular work. Perfusion of the brain and kidneys was unchanged.