Heterogeneity of endothelin/sarafotoxin receptors mediating contraction of the human isolated saphenous vein.

We investigated the effect of the ETA receptor antagonist, BQ-123 (0.1 and 1 microM), on contraction of the human isolated saphenous vein induced by endothelin-1 or sarafotoxin S6b. Contraction in response to endothelin-1 was not affected by BQ-123. In contrast, BQ-123 biphasically attenuated the contractions due to sarafotoxin S6b. These data indicate that (i) endothelin-1 induces contractions of the human saphenous vein via a non-ETA receptor and (ii) contractions in response to sarafotoxin S6b are mediated in part via a receptor different from the receptor mediating contraction due to endothelin-1.