Epicardial and endocardial coronary microvascular responses: effects of ischemia-reperfusion.
To examine whether endocardial microvascular function is preferentially impaired by ischemia and reperfusion, we studied endothelium-dependent responses of epicardial and endocardial coronary microvessels (130-220 microns) from control pigs and from pigs subjected to 1-h regional myocardial ischemia (circumflex occlusion) followed by 1-h reperfusion (n = 8) in vitro using videomicroscopy. In control animals (n = 8), no significant transmural differences were apparent in microvascular responses to the endothelium-dependent agents bradykinin or the calcium ionophore A23187, to the endothelium-independent agent sodium nitroprusside (SNP), or to adenosine. Serotonin caused a slight but statistically insignificant greater relaxation of endocardial than of epicardial microvessels. After ischemia-reperfusion, relaxations to all endothelium-dependent agents (serotonin, bradykinin, A23187) and to adenosine were significantly reduced (p < 0.05 for all agents) as compared with the respective control responses. There were no significant differences between epicardial and endocardial responses in the ischemia-reperfusion group for any of the vasoactive agents. Endothelium-independent responses to SNP were not affected by ischemia-reperfusion, indicating no alteration in the ability of vascular smooth muscle to relax through guanylate cyclase-mediated mechanisms. Control epicardial microvascular responses were examined after endothelial denudation and after pretreatment with NG-monomethyl-L-arginine (L-NMMA), indomethacin, or glibenclamide.(ABSTRACT TRUNCATED AT 250 WORDS)
Piana
R N
RN
Department of Surgery, Beth Israel Hospital, Boston, Massachusetts 02215.
Shafique
T
T
Dai
H B
HB
Sellke
F W
FW
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D003326:Coronary Circulation; D004699:Endocardium / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000502:physiology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000503:physiopathology; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D015427:Reperfusion Injury / Q000503:physiopathology*; D012701:Serotonin / Q000494:pharmacology; D013552:Swine; D019323:omega-N-Methylarginine
D009599:Nitroprusside; D019323:omega-N-Methylarginine; D012701:Serotonin; D000001:Calcimycin; D001120:Arginine; D006162:Guanylate Cyclase; D000241:Adenosine; D001920:Bradykinin; D005905:Glyburide; D007213:Indomethacin