A role of protein kinase C in signal reactions in outer segments of the bovine retinal rods

The effect of modulators of protein kinase C activity on Ca2+ translocation in dark-adapted and bleached retinal rod outer segments (ROS) was studied. The activators (1,2-diacyl glycerol and phorbol-12-myristate-13-acetate) and the inhibitor (chelerythrine chloride) of protein kinase C were shown to stimulate and inhibit the ATP-dependent Ca(2+)-uptake in dark-adapted retinal ROS, correspondingly. Apparently, this action is due to the influence of protein kinase C on Ca(2+)-ATPase activity in these vesicular structures. No involvement of modulators of protein kinase C activity on ATP-dependent Ca(2+)-uptake in bleached retinal ROS was found. The influence of protein kinase C on Ca(2+)-release from retinal ROS was observed. It was shown that the activators and inhibitors of protein kinase C increased the efficiency of this process both in dark-adapted and bleached retinal ROS. The mechanisms of action of the protein kinase C activity modulators on the Ca(2+)-uptake and Ca(2+)-release in retinal ROS are discussed.