Subtypes of losartan-sensitive angiotensin receptor in the rabbit pulmonary artery.

1. The short rabbit pulmonary artery was denuded of endothelium and divided into three sections, the cardiac end (cardiac), middle and pulmonary end (pulmonary) sections, respectively. Des-Asp-angiotensin I attenuated the contractions of the cardiac and middle sections to transmural nerve stimulation but potentiated the contractions in the pulmonary section. 2. The actions of the nonapeptide were inhibited completely by 10(-6) M losartan; however, a similar concentration of PD123319 had no effect. Indomethacin (10(-6) M) also inhibited completely the attenuation in the cardiac and middle sections but had no effect on the potentiation seen in the pulmonary section. 3. The data suggest that the two differential responses of the pulmonary artery to des-Asp-angiotensin I are mediated by two separate subtypes of the losartan-sensitive angiotensin AT1 receptor.