Regional differences in mechanism of action of oxygen on hamster arterioles

Leukotrienes have been implicated in the arteriolar constriction induced by elevated PO2 in the hamster cheek pouch. The role of leukotrienes in arteriolar O2 reactivity in other tissues has not been studied. To test the hypothesis that leukotrienes mediate O2 reactivity in all tissues, the effects of a leukotriene receptor antagonist, SKF-102922 (10 microM), a 5-lipoxygenase inhibitor, SC-43251 (30 microM), and a 5-lipoxygenase-activating protein antagonist, MK-886 (10 microM), on arteriolar O2 reactivity in hamster cheek pouch were compared with their effects on cremasteric arteriolar O2 reactivity. All three agents significantly decreased O2-induced arteriolar constriction in the cheek pouch, as reported previously. However, none of the antagonists inhibited O2-induced constriction of cremasteric arterioles. The efficacy of the leukotriene receptor antagonist, SKF-102922, was verified in the cremaster muscle: 10 microM SKF-102922 completely abolished constriction induced by topical application of leukotriene D4. These data support the hypothesis that leukotrienes mediate O2 reactivity in the cheek pouch. However, leukotrienes do not appear to mediate O2 reactivity in the cremaster muscle. These data suggest that there are significant regional differences in the mechanism of action of O2 on arterioles.