Stimulation of ouabain‐sensitive 86Rb+ uptake and Na+,K+‐ATPase α‐subunit phosphorylation by a cAMP‐dependent signalling pathway in intact cells from rat kidney cortex

[摘要]

We investigated in intact cortical kidney tubules the role of PKA-mediated phosphorylation in the short-term control of Na⁺,K⁺-ATPase activity. The phosphorylation level of Na⁺,K⁺-ATPase was evaluated after immunoprecipitation of the enzyme from ³²P-labelled cortical tubules and the cation transport activity of Na⁺,K⁺-ATPase was measured by ouabain-sensitive ⁸⁶Rb⁺ uptake. Incubation of cells with CAMP analogues (8-bromo-cAMP, dibutyryl-cAMP) or with forskolin plus 3-isobutyl-1-methylxanthine increased the phosphorylation level of the Na⁺,K⁺-ATPase α-subunit and stimulated ouabain-sensitive ⁸⁶Rb⁺ uptake. Inhibition of PKA by H-89 blocked the effects of dibutyryl-cAMP on both phosphorylation and ⁸⁶Rb⁺ uptake processes. The results suggest that phosphorylation by PKA stimulates the Na⁺,K⁺-ATPase activity.

[学科分类] 生物化学/生物物理

[关键词] Na+;K+-ATPase;Rubidium uptake;Protein phosphorylation;cAMP analog;Forskolin;Rat kidney cortex