Effect of cAMP-Dependent Protein Kinase on Catecholamine Secretion from Bovine Adrenal Chromaffin Cells

Abstract

We examined the role of cAMP-dependent protein kinase in Ca"-elicited catecholamine secretion from bovine adrenal chromaffin cells. When the digitonin-treated cells were incubated with the catalytic subunit of cAMP-dependent protein kinase, the secretion of catecholamines from the cells occurred in the absence of Ca 2+. The effect of the catalytic subunit was dependent on its activity (50-100 units/ml) and the presence of ATP-Mg2+ in the incubation medium. However, incubation of the cells with the regulatory subunit of cAMP-dependent protein kinase did not affect the secretion. Ca 2+ (43 nM -10 [M) also increased the secretion, which was ATP-Mg2+-dependent.The catalytic subunit (25-200 units/ml) enhanced the Ca2+-evoked secretion at the suboptimal but not optimal Ca 21 concentration, which induced maximal secretion. A potent synthetic peptide inhibitor of cAMP-dependent protein kinase abolished the catalytic subunit-induced secretion, but not the Ca2+-evoked secretion. On the other hand, K252a, a potent inhibitor of protein kinases, inhibited both the catalytic subunit-induced and the Ca2+-evoked secretion, but not KT5823, a much less potent inhibitor of protein kinases. These results strongly suggest that the catalytic subunit of cAMP-dependent protein kinase produces the secretion of catecholamines via protein phosphorylation. The results further suggest that the cAMP-dependent protein kinase does not participate in an intrinsic process of Ca2+-elicited secretion but it may act as a modulator.

The crosstalks between adipokines and catecholamines

“…In addition, leptin increases cAMP level as well as PKC activity and expression in porcine chromaffin cells (Takekoshi et al, 1999;Takekoshi et al, 2001b). It is well known that PKC and cAMP/PKA are potent promoters for triggered catecholamine secretion (Tachikawa et al, 1995;Yang et al, 2002;Xue et al, 2009a).…”

Study of adipokine secretion and their functions.

“…In addition, leptin increases cAMP level as well as PKC activity and expression in porcine chromaffin cells (Takekoshi et al, 1999;Takekoshi et al, 2001b). It is well known that PKC and cAMP/PKA are potent promoters for triggered catecholamine secretion (Tachikawa et al, 1995;Yang et al, 2002b).…”