The Effect of Carbon Monoxide on Contraction, Cytosolic Ca2+ Level and Ionic Currents in Guinea Pig Ileal Smooth Muscle

Abstract

The aim of this study was to clarify the mechanism of the inhibitory0aaction of carbon monoxide (CO) on contraction, by measuring cytosolic0aCa2+ level ((Ca2+)i) and ionic currents in guinea-pig ileum. CO (10%)0ainhibited 40 mM KCl-induced contraction and this effect was blocked by0aODQ (1 micrometer), a soluble guanylyl cyclase (sGC) inhibitor. CO inhibited0athe 40 mM KCl-induced contraction without changing (Ca2ence of CO, cumulative addition of KCl induced0asmaller contraction than in the absence of CO. On the other hand, the0aincrease in (Ca2onship shifted downwards. Using the patch clamp technique with a0aholding potential of -60 mV, we found that CO had little effect on the0apeak Ba currents (IBa) when voltage was stepped from -60 mV to 0 mV. In0aaddition, CO showed no effect on the depolarization-activated outward0aKotassium currents in guinea-pig ileum.