Effects of buspirone on plasma catecholamines, heart rate, and blood pressure in stressed and nonstressed rats.

The influence of buspirone upon plasma catecholamine levels, heart rate, and mean arterial blood pressure was studied in stressed and nonstressed rats. Measures were obtained directly via indwelling aortic catheters. Drug or vehicle were given acutely (10 mg/kg, IP) or twice a day for 10 days (10 mg and 20 mg/kg, SC). In nonstressed rats, a single dose of buspirone increased markedly plasma norepinephrine and epinephrine levels and decreased significantly heart rate with no effect on blood pressure. During stress, stress-induced increases in catecholamine levels were further elevated by the drug, whereas stress-induced increases of heart rate and mean arterial blood pressure were reduced. In chronically-pretreated rats, the effects of buspirone were similar to those observed after an acute injection. These effects of buspirone on plasma catecholamines are very different from those seen with other anxiolytics, whereas effects on heart rate and blood pressure are more similar.