Heme Oxygenase-1 Deficiency Leads to Alteration of Soluble Guanylate Cyclase Redox Regulation

摘要

Heme oxygenase-1 knockout, Hmox1(−/−), mice exhibit exacerbated vascular lesions after ischemia-reperfusion and mechanical injury. Surprisingly, we found no studies that reported contractile responses and sensitivity to vasorelaxants in Hmox1(−/−) mice. The contractile responses [superior mesenteric arteries (SMA), from female Hmox1(−/−) mice] exhibited increased sensitivity to phenylephrine (p < 0.001). Cumulative addition of acetylcholine relaxed SMA, with the residual contraction remaining 2 times higher in Hmox1(−/−) mice (p < 0.001). Sodium nitroprusside (SNP, an NO donor) and 3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole [YC-1; acts directly on soluble guanylate cyclase (sGC)] led to further relaxation, yet the residual contraction remained 2 to 3 times higher in Hmox1(−/−) than Hmox1(+/+) mice (p < 0.001). Branches from Hmox1(−/−) mesenteric and renal arteries also showed reduced relaxation (p < 0.025). Relaxation of SMA was measured to 4-({(4-carboxybutyl) [2-(5-fluoro-2-{[4′-(trifluoromethyl) biphenyl-4-yl] methoxy}phenyl)ethyl]amino}benzoic acid (BAY 60-2770), which is a more effective activator of oxidized/heme-free sGC; and to 5-cyclopropyl-2-{1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl}-pyrimidin-4-ylamine (BAY 41-2272), a more effective stimulator of reduced sGC. Hmox1(−/−) arteries were 15 times more sensitive to BAY 60-2770 (p < 0.025) than were Hmox1(+/+) arteries. Pretreatment with 1H-[1,2,4]oxadiazolo[3,4-a]quinoxalin-1-one (ODQ), an oxidizer of sGC, predictably shifted the BAY 60-2770 response of Hmox1(+/+) to the left (p < 0.01) and BAY 41-2272 response to the right (p < 0.01). ODQ had little effect on the responses of Hmox1(−/−) arteries, indicating that much of sGC was oxidized/heme-free. Western analyses of sGC in SMA indicated that both α1and β1 subunit levels were reduced to <50% of Hmox1(+/+) level (p < 0.025). These findings support the hypothesis that the antioxidant function of Hmox1 plays a significant role in the maintenance of sGC in a reduced state, which is resistant to degradation and is sensitive to NO. This function may be especially important in reducing vascular damage during ischemia-reperfusion injury.