Mosse I. Comparative study of NO-donors during normal and decreased oxygenation

It has been shown that low PO2(hypoxia) increased the contractile force developed by smooth muscle (SM) of porcine coronary arteries. The similar effect was reproduced by the inhibitor of nitric oxide (NO) syntase (NOS); this hypoxic contraction failed when SM were pretreated withNOS inhibitor added to the hypoxic bath solution. The relaxant effect of authentic NO and its donors (nitriglycerin, sodium nitroprusside, SIN-1) were studied in porcine epicardic coronary arteries at normal conditions and during oxygenation lack. The effect of authentic NO and therapeutic NO-donors increased significantly during hipoxia and NNA action.We suggest that: i) NOS inhibition may be involved in hupoxia - induced coronary spasm development and ii) hypoxia may change the reactivity of SM to NO-donors. The therapevtic NO-donors had disposed accordingly its relaxation in normoxia as follows: SIN->sodium nitroprusside->nitroglycerin