Abstract-NO is known to have several important vasculoprotective actions. Although NO is synthesized by 3 different NO synthase (NOS) isoforms, the vasculoprotective action of individual NOS isoforms remains to be clarified. Permanent ligation of the left common carotid artery was performed in control, endothelial NOS (eNOS) knockout (eNOS-KO), and inducible NOS (iNOS) knockout (iNOS-KO) mice. Four weeks after the procedure, neointimal formation and reduction of cross-sectional vascular area (constrictive remodeling) were noted in the left carotid artery.In the eNOS-KO mice, the extent of neointimal formation was significantly larger than in the control or iNOS-KO mice, whereas the extent of vascular remodeling was the highest in the iNOS-KO mice compared with other 2 strains. Antiplatelet therapy with aspirin or antihypertensive treatment with bunazosin failed to inhibit the accelerated neointimal formation in the eNOS-KO mice. These results indicate that eNOS and iNOS have different vasculoprotective actions against the vascular lesion formation caused by blood flow disruption in vivo: NO derived from eNOS inhibits neointimal formation, whereas NO derived from iNOS suppresses the development of constrictive remodeling. Indeed, reduction of production and/or action of NO predisposes the blood vessel to arteriosclerosis. 1-3 NO is synthesized by 3 different isoforms of NO synthase (NOS). Endothelial NOS (eNOS) and neuronal NOS are constitutively expressed mainly in endothelial cells and nitrergic nerves, respectively, synthesizing a small amount of NO under basal conditions and on stimulation by various agonists. 1-3 By contrast, inducible NOS (iNOS) is expressed when stimulated by inflammatory stimuli, synthesizing a large amount of NO in a transient manner. [1][2][3] Recent advances in genetic engineering have led to the development of mice that are deficient in specific target genes, including eNOS 4 and iNOS. 5,6 The mice that are deficient in the eNOS gene (eNOS-KO mice) have been reported to have mild hypertension, 4 whereas mice that are deficient in the iNOS gene (iNOS knockout [KO] mice) have been reported to have altered immune response and reduced tolerability against infections. 5 Although the possible vasculoprotective actions of NOS have been examined in a different model for eNOS (cuff placement around the femoral artery) 6 and iNOS (cardiac transplant model), 7 the possible difference in the vasculoprotective roles of those NOS isoforms remains to be clarified in the same model.Thus, the present study was designed to address this point in the carotid artery ligation model in mice. 8 MethodsThe present study was reviewed and approved by the Scientific Committee of Kyushu University. AnimalsiNOS-KO mice were provided by Dr Mudgett (Merck Research Laboratories, Rahway, NJ), 4 and eNOS-KO mice were provided by Dr Fishman (Harvard Medical School, Boston, Mass). 5 For wild genotype control, we used C57BL/6 mice. 4,5 In preliminary studies, we confirmed no endothelial production of NO in eNOS-KO mice an...

Serotonin is one of the most important vasoactive substances and has been implicated in the pathogenesis of coronary artery spasm and of acute coronary syndrome. We have recently demonstrated that local and long-term treatment with interleukin-1beta(IL-1beta) causes coronary arteriosclerotic changes and hyperconstrictive responses to serotonin in pigs in vivo. However, it remains to be examined which serotonergic (5-HT) receptor subtype mediates coronary spasm and whether alterations in serotonergic receptors are involved in the abnormality. In this study, we examined the inhibitory effect of sarpogrelate, a selective 5-HT2A serotonergic receptor antagonist, on the serotonin-induced coronary spasm as well as the possible alterations of serotonergic receptors in our porcine model. A segment of the porcine coronary artery was carefully dissected and aseptically wrapped with cotton mesh absorbing IL-1beta-bound microbeads from the adventitia. Two weeks after the procedure, angiographic study was performed, followed by binding assay for 5-HT1B and 5-HT2A serotonergic receptors and reverse transcription-polymerase chain reaction (RT-PCR) analysis for mRNA of those receptors. Angiographic study showed coronary vasospastic responses to serotonin at the IL-1beta-treated site. Sarpogrelate dose-dependently inhibited the serotonin-induced coronary spasm, but it did not affect the prostaglandin F2alpha-induced vasoconstriction. Radiolabeled receptor-binding assay showed that receptor affinity or receptor number of the 5-HT1B, or 5-HT2A receptors did not differ significantly between the spastic and the control sites. Furthermore, RT-PCR analysis showed that the expression of neither 5-HT2A nor 5-HT1B receptor mRNA was significantly altered at the spastic site. These results indicate that serotonin-induced coronary spasm is mediated primarily by 5-HT2A receptor in our porcine model, although the 5-HT2A receptor was not up-regulated, suggesting that alteration in the signal-transduction pathway for vascular smooth muscle contraction beyond the 5-HT2A receptor plays a primary role in the pathogenesis of coronary spasm in our porcine model.

Adenovirus-mediated CNP gene transfer with the IABC system may be a useful gene therapy to prevent restenosis after PTCA in vivo.