Different responses of the human gastroepiploic and internal mammary arteries to vasoactive peptides.

Abstract

Peptidergic influences have been implicated in the control of tone in human arteries. We have examined the response of human gastroepiploic arteries (GEA) and internal mammary arteries (IMA) to three vasoactive peptides in vitro. Vasoactive intestinal peptide (VIP, 10(-11) to 3 x 10(-7) M) elicited relaxations in the GEA and IMA [maximum generated response (Emax) 74.6 +/- 9.4 and 56.5 +/- 7.7%, respectively] that were significantly reduced after removal of endothelium. NG-monomethyl-L-arginine (L-NMMA) and indomethacin partially inhibited the response of the GEA to VIP (P < 0.05). In the IMA, VIP-induced relaxation was significantly attenuated by L-NMMA but not indomethacin. Bombesin (10(-10) to 3 x 10(-6) M) produced endothelium-dependent relaxation selectively in the GEA, which was only inhibited by indomethacin (Emax reduced from 59.0 +/- 10.0 to 12.8 +/- 4.9%, P < 0.001). Bombesin elicited a weak endothelium-independent constriction in the IMA, giving 12.7 +/- 1.2% of the response to 90 mM KCl. Gastrin (10(-10) to 3 x 10(-7) M) had no effect on IMA segments but induced a relaxation of 40.0 +/- 3.2% in the GEA via a direct action on the smooth muscle. It is concluded that human GEA and IMA exhibit heterogenous responses to VIP, bombesin, and gastrin that may have important physiological and clinical implications.