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 end (cardiac), middle and pulmonary end (pulmonary) sections, respectively. Des-Asp-cardiac 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 AT(1) receptor.