Acute and chronic effects of rilmenidine on baroreflex function in conscious dogs

The effects of acute and chronic administration of rilmenidine on blood pressure, heart rate and baroreflex function were assessed in two groups of six conscious dogs. Baroreflex function was evaluated using increasing doses of glyceryl trinitrate and phenylephrine to decrease and increase blood pressure respectfully. Acute administration of rilmenidine (1 mg/kg p.o.) reduced (P less than 0.05) blood pressure and heart rate, and enhanced (P less than 0.05) baroreflex function to increases in blood pressure with phenylephrine, but not to decreases in blood pressure by glyceryl trinitrate. Following chronic administration of rilmenidine, blood pressure remained lowered while heart rate and baroreflex function returned to control values.