Alteration of the microenvironment in plasma membranes of rat enterocytes after Escherichia coli heat stable enterotoxin treatment: effect on protein kinase C activity

Abstract

Plasma membranes isolated from Escherichia coli heat stable enterotoxin (STa) treated rat enterocytes were studied in respect to protein kinase C activity and fluidity change. Pretreatment of enterocytes with STa increased the membrane bound protein kinase C activity about 5 fold as compared to control. STa treatment made the membrane more fluid as evident from a higher phospholipid/cholesterol ratio and greater unsaturated fatty acid levels. Moreover, the phase transition temperature of the STa treated membrane appeared to be significantly lower than that of the corresponding control membrane, thereby further indicating a rise in fluidity of the membrane in the former case. Our results, therefore, suggested that following STa enterotoxin treatment an appropriate fluid environment in the rat intestinal cell membrane was essential for the activation of protein kinase C.