Acute effect of indenolol on systemic arterial pressure and heart rate in the rat.

The acute effects of single intravenous or oral doses of indenolol, as compared to that of propranolol and pindolol, on systemic blood pressure and heart rate were investigated in the rat. In reserpinized anaesthetized rats propranolol neither affected diastolic blood pressure nor heart rate and pindolol produced a dose-related tachycardia with moderate hypotensive effect. After indenolol the fall in diastolic blood pressure was concomitant with a very low increase in heart rate. Both effects were prevented by propranolol. In conscious SHRs the acute hypotensive effect of oral indenolol and pindolol was associated with marked bradycardia and moderate tachycardia respectively, while the decrease in heart rate following propranolol was concomitant to a slight increase in blood pressure. The possibility that the acute haemodynamic changes observed in rats after indenolol may be due to intrinsic sympathomimetic activity predominant at beta 2-vascular adrenergic receptor level is discussed.