Phosphorylation‐independent inhibition by intracellular cyclic nucleotides of brain inwardly rectifying K+ current expressed in Xenopus oocytes

FEBS Letters

Ito, Hiroyuki¹  Kurachi, Yoshihisa²  Tada, Yoshihiko²  Tsuchimochi, Hidetsugu² 

[1] Department of Cell Biology and Signaling, Yamagata University School of Medicine, 2-2-2, Iida-nishi, Yamagata 990–23, Japan;Department of Pharmacology II, Faculty of Medicine, Osaka University, 2-2, Yamada-oka, Suita, Osaka 565, Japan

关键词: Potassium channel;    Brain;    Isoproterenol;    Dibutylyl cyclic AMP;    Dibutylyl cyclic GMP;    Xenopus oocyte;   

DOI  :  10.1016/S0014-5793(96)01458-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

An inwardly rectifying K⁺ current, which was heterologously expressed in Xenopus oocytes, was inhibited by isoproterenol, a β-adrenergic agonist. Poly(A)⁺ mRNA isolated from guinea-pig brain was injected into oocytes 2–3 days before experiments. Isoproterenol inhibition of the K⁺ current was time- and voltage-dependent: the inhibition became faster and more pronounced as the command voltage steps were applied to more negative potentials. This inhibition was prevented by propranolol. Dibutylyl cyclic (dB-c) AMP could mimic the effect of isoproterenol, while injection of the catalytic subunit of cAMP-dependent protein kinase into the oocytes did not affect the K⁺ current. Inhibitors of the protein kinases, WIPTIDE and H-8, did not prevent the inhibition by dB-cAMP. Furthermore, dB-cGMP also inhibited the K⁺ current in a similar time- and voltage-dependent manner. We propose that the phosphorylation-independent action of cyclic nucleotides mediates β-adrenergic inhibition of brain inwardly rectifying K⁺ channels expressed in Xenopus oocytes.

【 授权许可】

Unknown