Abstract
Somatostatin analogues are capable of inhibiting vascular smooth muscle and endothelial cell proliferation. However, little is known about the effect of somatostatin on vascular responses in endothelium-denuded coronary arteries in vitro. The aim of this work was to determine whether or not somatostatin prevented the contractile response induced by 5-hydroxytryptamine and acetylcholine in endothelium-denuded rabbit coronary arteries. Somatostatin attenuated the contraction produced by 5-hydroxytryptamine in both proximal (PC) and distal coronary (DC) arteries (contraction induced by 10−4 M 5-hydroxytryptamine was inhibited by 10−6 M somatostatin by 90.8 ± 11.0% (P<0.001, n = 9) and by 46.2 ± 14.0% (P<0.05, n = 9) in DC and PC, respectively), but concentration-dependently decreased the contraction induced by U46619 (11α-epoxy-methanoprostaglandin F2α) only in PC arteries, suggesting that the response of PC and DC arteries to somatostatin were qualitatively different. Furthermore, we suggest that somatostatin may enhance acetylcholine-induced relaxation by combination of increasing endothelium-dependent relaxation (by a NO-dependent mechanism) and blocking contraction at the muscle level.
