Plasma renin activity and vasodepressor action of prostacyclins with modified omega-side chain in anesthetized rats

The effects of intravenous injection of prostacyclin (PGI2) and two of its analogues with modified omega-side chain on systemic blood pressure and on plasma renin activity were investigated in anesthetized rats. The PGI2 -methylester analogues with replacement of the n-pentyl moiety attached to C-15 by cyclohexyl or 3-thienyloxymethyl had exactly the same vasodepressor activities as PGI2. Despite these equipotent effects on blood pressure a marked difference between PGI2 and the analogues with respect to stimulation of plasma renin activity could be demonstrated. The cyclohexyl as well as the 3-thienyloxymethyl analogue induced a significantly stronger increase of plasma renin activity than PGI2. These findings strengthen the view of a direct involvement of prostacyclins in renin release mechanisms.