Different role of nitric oxide and endothelium-derived hyperpolarizing factor in endothelium-dependent hyperpolarization and relaxation in porcine coronary arterial and venous system.
OBJECTIVE
We compared the basal and bradykinin (BK)-induced NO release and endothelium-derived hyperpolarizing factor-mediated function between coronary arteries and cardiac veins.


RESULTS
Isolated coronary vessels (large arteries, cardiac veins as well as microvessels) were studied. An NO-specific electrode and a conventional intracellular glass microelectrode were used to directly measure NO released from endothelial cells and hyperpolarization of smooth muscle cells in conduit coronary vessels. The basal and BK-induced release of NO was 14.2 +/- 2.0 nmol/L and 237.1 +/- 27.2 nmol/L (n = 8) in the artery, significantly greater than in veins (8.0 +/- 1.1 nmol/L and 135.6 +/- 14.5 nmol/L, n = 8, P < 0.01). The BK-induced hyperpolarization was significantly reduced by N-nitro-L-arginine, indomethacin, and hemoglobin in both arteries and veins and was greater in the arteries. The EDHF-mediated relaxation was significantly higher in the arteries than in veins, greater in microveins than in large veins, and almost abolished by charybdotoxin and apamin.


CONCLUSIONS
Both NO and EDHF are involved in the regulation of the vascular tone in the coronary arterial and venous systems but the amount of NO release and the EDHF-mediated relaxation and associated hyperpolarization are less significant in the vein than in the artery in the coronary system.
Zhang
Rong-Zhen
RZ
Department of Surgery, The Chinese University of Hong Kong, Hong Kong SAR, China.
Yang
Qin
Q
Yim
Anthony P C
AP
Huang
Yu
Y
He
Guo-Wei
GW
D000818:Animals; D001685:Biological Factors / Q000502:physiology*; D001920:Bradykinin / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D001685:Biological Factors; C067410:endothelium-dependent hyperpolarization factor; D009569:Nitric Oxide; D001920:Bradykinin