Borasio P G, Vassalle M
Arch Int Physiol Biochim. 1975 Feb;83(1):79-97. doi: 10.3109/13813457509069842.
(1) The inhibition of potassium uptake by low concentration of norepinephrine (3 X 10-8 M) and of dibutyryl cyclic AMP (DBcAMP, 10 minus5 M) was studied in cardiac Purkynĕ fibres. (2) The inhibitory action of DBcAMP on K uptake was abolished by the alpha blocker phentolamine. (3) Norepinephrine alone decreased K uptake and such inhibition was somewhat larger when DBcAMP was added. DBcAMP alone caused the usual decrease in K uptake but addition of norepinephrine abolished it. (4) The inhibition caused by norepinephrine reduced the increase in uptake caused by a high concentration (10 minus 3 M) of DBcAMP. (5) The inhibitory effect of norepinephrine was reversed in the presence of high concentration of magnesium (5.25 mM). (6) The inhibitory effect of norepinephrine was reversed by aminophylline and abolished by caffeine. (7) The inhibitory action of norepinephrine and BCcAMP was reversed or abolished, respectively, by imidazole. (8) It is concluded that the inhibition of potassium uptake by low concentration of DBcAMP is mediated by an alpha receptor mechanism and that possibly the "receptors" for this effect of norepinephrine and DBcAMP are located at different sites. Also it appears that DBcAMP may be acting at the membrane and that the action of methylxanthines and imidazole is not necessarily mediated only by a modification of phosphodiesterase activity.
(1) 在心脏浦肯野纤维中研究了低浓度去甲肾上腺素（3×10⁻⁸M）和二丁酰环磷腺苷（DBcAMP，10⁻⁵M）对钾摄取的抑制作用。(2) α受体阻滞剂酚妥拉明消除了DBcAMP对钾摄取的抑制作用。(3) 单独使用去甲肾上腺素会降低钾摄取，当加入DBcAMP时这种抑制作用会稍大一些。单独使用DBcAMP会使钾摄取正常降低，但加入去甲肾上腺素后这种降低作用消失。(4) 去甲肾上腺素引起的抑制作用减弱了高浓度（10⁻³M）DBcAMP引起的摄取增加。(5) 在高浓度镁（5.25mM）存在下，去甲肾上腺素的抑制作用被逆转。(6) 氨茶碱可逆转去甲肾上腺素的抑制作用，咖啡因可消除该作用。(7) 咪唑分别逆转或消除了去甲肾上腺素和BCcAMP的抑制作用。(8) 得出结论：低浓度DBcAMP对钾摄取的抑制作用是由α受体机制介导的，去甲肾上腺素和DBcAMP这种作用的“受体”可能位于不同位点。此外，似乎DBcAMP可能作用于细胞膜，甲基黄嘌呤和咪唑的作用不一定仅通过改变磷酸二酯酶活性来介导。
