Development of the pencil-typed imaging system to evaluate the disturbance of coronary microcirculation during coronary ischemia-reperfusion injury

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We constructed the pencil-typed imaging system to evaluate the disturbance of mesenteric and coronary microcirculation during reactive hyperemia (RH). We have succeeded in quantitatively evaluating the in-vivo microcirculation with our videomicroscope system. Mesenteric arterioles from wild-type and Cu, Zn-SOD^<-/-> mice were continuously observed by a microscope during acetylcholine (ACh)-induced vasodilatation and RH in the cyclooxygenase blockade under the following 3 conditions; control, L-NMMA, and L-NMMA+catalase. In the mesenteric arterioles of wild-type mice, endothelium-dependent relaxations to ACh and vasodilatation during RH were resistant to L-NMMA, but were markedly inhibited by L-NMMA+catalase. In mesenteric arterioles of Cu, Zn-SOD^<-/->mice, L-NMMA markedly inhibited the relaxations to ACh and vasodilatation during RH but were not inhibited by the addition of catalase. RH-induced increase in blood flow after L-NMMA was significantly increased in the wild-type mice by microsphere, whereas in the Cu, Zn-SOD^<-/-> mice, it was significantly reduced. In the mesenteric arterioles of the Cu, Zn-SOD^<-/-> mice, tempol, an SOD mimetic, significantly increased the ACh-induced vasodilatation, and the enhancing effect of tempol was abolished by catalase. Endothelial Cu, Zn-SOD plays an important role for the endogenous H_2O_2 that contributes to RH in mouse mesenteric microvessels in vivo.