Differences in papaverine inhibition of prostaglandin-induced contraction of aortic strips from normal and spontaneously hypertensive rats (SHR)

Papaverine was studied for its ability to inhibit prostaglandin (PG) E 2, F 2α, A 1, as well as norepinephrine (NE)-and KCl-induced contractions of aortic strips from normal and spontaneously hypertensive rats (SHR). There was a 2.8, 5.1, and 6.2 fold increase in the concentration of papaverine required 50% inhibition of PGA 1, PGF 2α and PGE 2 contractions of aortic strips from SHR compared to normal tissues. There was no significant difference in the inhibiton of NE- or KCl-induced contractions of aortae from SHR compared to controls. The relative resistance of aortae from SHR to the inhibitory effect of papaverine on pG-induced contractions may be explained in terms of the higher phosphodiesterase activity in aortae from SHR and/or possible differences in PG-induced Ca 2+ translocation compared to normal tissue.