Angiotensin(1-7) had a compound effect on blood pressure of pithed Sprague-Dawley rats. The initial phase of the response consisted of an increase in MAP of short duration and independent of injected dose, followed by a decline of arterial pressure to values below baseline. Both the magnitude (range: -4 +/- 1 to -13 +/- 1 mmHg) and the duration (range: 83 +/- 13 to 255 +/- 17 s) of the depressor response correlated with the dose of peptide. Indomethacin (5 mg/kg) eliminated the depressor component. Only [Sar1,Thr8]Ang II inhibited the effect of Ang(1-7) completely. We conclude that angiotensin(1-7) possesses myotonic actions that are in part related to release of vasodilator prostaglandins through an angiotensin receptor other than AT1 or AT2.