ATP RELEASE BY ANGIOTENSIN-II FROM SEGMENTS AND CULTURED SMOOTH-MUSCLE CELLS OF GUINEA-PIG TAENIA-COLI

Effects of angiotensin II on ATP release were evaluated in segments an d cultured smooth muscle cells from the guinea-pig taenia coli. In the segments angiotensin II (0.3-3 mu M) elicited release of ATP which wa s blocked by losartan and SC-52458, non-peptide angiotensin II type-1 receptor (AT(1))-antagonists, but not by PD-123319, an AT(2)-antagonis t. In superfused cultured cells, 10 mu M angiotensin II likewise elici ted release of ATP. Again the response was blocked by losartan and SC- 52458 bur not by PD-123319, These findings suggest that angiotensin II releases ATP from the smooth muscles by activation of angiotensin II- , presumably AT(1)-, receptors.