Endogenous phosphorylation of lysosomal proteins of rat heart and liver in the early postreanimation period

Abstract

The lysosomal fraction isolated in a PercoU gradient from rat liver and heart after 30 min of the postreanimation period following a 5-min heart arrest stimulated incorporation of 32p in total lysosomal protein. Addition of cAMP and protein inhibitor of cAMP-dependent protein kinase changed the rate of phosphorylation. Endogenous phosphorylation of total lysosomal protein in the postreanimation period was reduced in the heart and increased in the liver. This may be due to a change in the intracellular level of cAMP, which fell in the heart and rose in the liver. Key Words: lysosomes; cAMP-dependent phosphorylation; postreanimation period; heart; liverThe lysosomal enzymes play an important role in the development of destructive changes in the heart and liver tissues during both hypoxia and ischemia, as well as during postischemic rehabilitation [8]. The permeability of lysosomal membranes and the activity of acid hydrolases in the cytosol of hepatic and myocardial cells have been shown to be increased in the early postischemic and postreanimation period [2,3]. The detected relationship between the intracellular cAMP concentration and the state of lysosomal membranes during postischemic recovery permits one to hypothesize a cAMP-mediated mechanism regulating lysosomal activity [6,10].In this research we investigated the relationship between the rate of endogenous phosphorylation of proteins in the lysosomal fraction of rat liver and heart and the level of cAMP during the early postreanimation period.