[Role of extracellular pO2 and pCO2 in membrane mechanisms regulating cerebral artery smooth muscle].

The O2 insufficiency and excessive CO2 relaxed the brain arteries smooth muscles abolishing their spontaneous electrical and contractile activity. The hypoxia effects were potentiated in the hypopotassium milieu and weakened in the hyperpotassium and hyposodium solutions. Hypercapnic responses insignificantly both in hypo- and hyperpotassium solutions whereas hyposodium one enhanced them. A decrease of the extracellular PO2 seems to reduce the excitability of membranes and to inhibit the active transport of Na+ and K+. CO2 appears to exert no considerable effect on the active transport processes but to interfere in the intracellular mechanisms of Ca2+ regulation.