[The role of phosphoinositides, protein kinase C and protein kinase A in the K+ regulatory signal transduction in human adrenocortical cells].

The messenger mechanisms mediating K+ regulatory signals in human adrenocorticocytes were studied. It was shown that potassium ions initiated decay of polyphosphoinositides to inositolphosphates and obviously diacylglycerol. The latter compounds activate protein kinase C as affected by different agonists. Using western blotting method we showed translocation of PKCalpha from cytosol to membranes after adrenal tissue preincubation in the medium with increased K+ content (8.5 mM). Translocation means activation of the enzyme. Activity of PKC increased in the microsomal fraction and did not change in cytosol. Increased concentration of K+ in the incubation medium also activates protein kinase A, although to a lesser extent compared to PKC. Unlike PKC activity of PKA was changed in cytosol as well. The possibility of involvement of several messenger systems in K+ signal transduction in human adrenocortical cells as well as the hypothesis on cross-talk between messenger mechanisms for main physiological agonists controlling aldosterone biosynthesis in the adrenals are discussed.