[Effect of metipranolol on the cardiovascular system of the rabbit in vivo during spontaneous and paced heart rhythm].

The effects of i.v. administration of metipranolol (Trimepranol, Biotika; 0.03; 0.15 and 0.3 mg.kg-1) and saline (1.0 ml.kg-1) on the cardiovascular system of rabbits in vivo have been determined under the conditions of the paced and non-paced heart. The administration of saline in the control group led to a mild decrease of dP/dtmax, minute blood flow through the abdominal aorta and slowing-down the cardiac frequency without significant changes in blood pressure in a. femoralis and stroke blood flow through the abdominal aorta. No practically important differences between the paced and non-paced conditions were found. The administration of Trimepranol led to a significant, dose dependent decrease in dP/dtmax, which was less expressed in the paced heart (in comparison with the non-paced heart) after the lowest dose of the drug; no such a difference was found after higher doses of Trimepranol. Reactions of blood pressure (no significant changes) and minute blood flow through the abdominal aorta (a mild decrease) to the administration of Trimepranol were similar both in the paced and in non-paced heart. A significant slowing-down of the spontaneous cardiac frequency after Trimepranol was dose-dependent and, in relation to this fact, a significant increase in stroke blood flow through the abdominal aorta was found. On the basis of the above-mentioned results, it is possible to conclude that the paced heart conditions do not unfavourably influence the effects of Trimepranol on the cardiovascular system of rabbits in vivo.