ALTERATION OF THE MICROENVIRONMENT IN PLASMA-MEMBRANES OF RAT ENTEROCYTES AFTER ESCHERICHIA-COLI HEAT-STABLE ENTEROTOXIN TREATMENT - EFFECTON PROTEIN-KINASE-C ACTIVITY

Plasma membranes isolated from Escherichia coli heat stable enterotoxi n (STa) treated rat enterocytes were studied in respect to protein kin ase C activity and fluidity change. Pretreatment of enterocytes with S Ta 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 unsa turated fatty acid levels. Moreover, the phase transition temperature of the STa treated membrane appeared to be significantly lower than th at of the corresponding control membrane, thereby further indicating a rise in fluidity of the membrane in the former case. Our results, the refore, suggested that following STa enterotoxin treatment an appropri ate fluid environment in the rat intestinal cell membrane was essentia l for the activation of protein kinase C.