EFFECT OF GLYCOSYLATED HEMOGLOBIN ON ENDOTHELIUM-DEPENDENT RELAXATIONOF OMENTAL ARTERIES FROM PREGNANT-WOMEN

OBJECTIVE: This study was intended to test the hypothesis that glycosy lated hemoglobin adversely affects endothelium-dependent vascular rela xation during pregnancy. STUDY DESIGN: Omental artery rings (3 mm) obt ained from patients undergoing cesarean delivery at term were suspende d in organ chambers for isometric tension recording in Krebs bicarbona te solution. They were bubbled with 5% carbon dioxide in air (37 degre es C, pH 7.4). After equilibration at 1-g passive tension and contract ion with endothelin 1, concentration-relaxation curves in response to bradykinin were determined in the presence or absence of oxyhemoglobin , glycosylated hemoglobin, or nitric oxide synthase inhibitors (N omeg a-nitro-L-arginine methyl ester or N omega-nitro-L-arginine). RESULTS: Oxyhemoglobin and glycosylated hemoglobin attenuated the endothelium- dependent relaxation induced by bradykinin. The inhibition did not dif fer significantly between the 2 nitric oxide scavengers and was of the same magnitude as that noted with the nitric oxide synthase inhibitor s. CONCLUSION: Glycosylation of hemoglobin does not change its effect on endothelium-dependent relaxation in human omental vessels during pr egnancy. These data do not support the hypothesis that glycosylated he moglobin may be the reason for abnormal endothelial function in diabet es.