[Role of lipid peroxidation in inhibiting cardiac Na, K-ATPase during stress].

Induction of lipid peroxidation (LPO) under emotional painful stress in rats in vivo and by the Fe2+ plus ascorbate system in vitro results in inactivation of Na,K-ATPase in the sarcolemma-rich membrane fraction of the heart. Activity of Mg-ATPase remains practically unchanged. The scavenger of lipid free radicals 4-methyl-2,6-ditertbutylphenol (ionol) prevents Na,K-ATPase inactivation in both cases. It is concluded that LPO plays the key role in the impairment of the heart Na-pump function under stress and that such impairment can be prevented by free radical scavengers. The stress-induced shifts in the ionic homeostasis in cardiomyocytes are discussed.