Effects of propranolol, nalorphine and haloperidol on the breathing and on the metabolism of PGI2 and TXA2 of normotensive and spontaneously hypertensive rats.

The influence of propranolol, nalorphine and haloperidol on the breathing pattern and on the blood levels of cyclooxygenase products of anaesthetized spontaneously-breathing normotensive Wistar rats (WR) and of spontaneously hypertensive rats (SHR) were investigated. The respiratory rate was higher and the effective lung resistance was smaller in the SHR than in the WR. Breathing frequency decreased after nalorphine in both groups, while only in SHR after haloperidol. Propranolol augmented the dynamic lung resistance in both groups. The blood 6-keto-PGF1 alpha level was higher and the TXB2 level was lower in the SHR than in the WR. The central inspiratory activity as well as the levels of peripherally acting substances involved in the regulation of respiration and in the control of bronchial smooth muscle tone are different in the SHR and WR.