Aldosterone Rapidly Represses Protein Kinase C Activity in Neonatal Rat Cardiomyocytesin Vitro

Atsuhisa Sato, Jun-Ping Liu, John W. Funder
1997 Endocrinology  
Aldosterone lowers protein kinase C (PKC) activity in myocyteenriched cultures from neonatal Sprague-Dawley rat hearts, with activity measured by the transfer of phosphate to myristolated alanine-rich C-kinase substrate, in the presence of Ca 2ϩ , phosphatidylserine, and diolein. The effect is rapid, with a significant effect after 1 min exposure, half maximal at Յ1 nM aldosterone, with steroids showing a hierarchy of potency aldosterone ϭ 9␣ fluorocortisol Ͼ deoxycorticosterone Ͼ
more » ... one Ͼ corticosterone Ͼ spironolactone. Both Ca 2ϩdependent and -independent PKC activity appear equally inhibited by aldosterone, and PMA-stimulated increases in PKC activity ap-pear similarly aldosterone-sensitive. No displaceable binding of [ 3 H]aldosterone to purified PKC can be shown, evidence against a direct effect of aldosterone on PKC; aldosterone does not alter basal or PMA-stimulated PKC activity in cardiac fibroblasts, evidence for a cell-specific mediator of the myocyte effect. Taken with the previous demonstration of the potentiation of aldosterone-specific MR-mediated effects by PKC activation, the present data argue for the existence of a complex cross-talk mechanism between aldosterone and factors affecting PKC activity in the heart. (Endocrinology 138: 3410 -3416, 1997)
doi:10.1210/endo.138.8.5352 pmid:9231795 fatcat:rhgqpwmb3fbdhek5b5foxn5lya