Ousterhout J M, Sperelakis N
Department of Physiology and Biophysics, University of Cincinnati, College of Medicine, Ohio 45267-0576.
Eur J Pharmacol. 1987 Nov 24;144(1):7-14. doi: 10.1016/0014-2999(87)90003-3.
The effects of cyclic nucleotide analogs and related agents on the Ca2+ dependent action potentials of cultured rat aortic smooth muscle cells (reaggregates) were examined. The action potentials were elicited by electrical stimulation in the presence of tetraethylammonium (TEA, 5-15 mM). Superfusion of the aortic cells with analogs of cyclic AMP (dibutyryl or 8-bromo-cyclic AMP, 1 mM), isoproterenol (1-10 microM) and forskolin (1-10 microM) depressed and abolished the TEA-induced action potentials. Abolition of the action potentials by these agents was reversible and was accompanied by some hyperpolarization of the membrane. Superfusion with 8-bromo-cyclic GMP (0.1-1 mM) also depressed or abolished the TEA-induced action potentials, whereas dibutyryl cyclic GMP (1 mM) and sodium nitroprusside (10 microM) had little effect. Synthetic atrial natriuretic factor (0.01-0.1 microM) had inhibitory effects in most experiments. Thus, depression of membrane excitability may be a contributing factor in the relaxation of aortic smooth muscle produced by some agents that increase intracellular levels of cyclic nucleotides.
研究了环核苷酸类似物及相关药物对培养的大鼠主动脉平滑肌细胞（重聚体）钙依赖性动作电位的影响。动作电位是在存在四乙铵（TEA，5 - 15 mM）的情况下通过电刺激引发的。用环磷酸腺苷类似物（二丁酰或8 - 溴环磷酸腺苷，1 mM）、异丙肾上腺素（1 - 10 μM）和福斯可林（1 - 10 μM）对主动脉细胞进行灌流，可抑制并消除TEA诱导的动作电位。这些药物对动作电位的消除是可逆的，并伴有膜的一些超极化。用8 - 溴环磷酸鸟苷（0.1 - 1 mM）灌流也可抑制或消除TEA诱导的动作电位，而二丁酰环磷酸鸟苷（1 mM）和硝普钠（10 μM）的作用很小。在大多数实验中，合成心房利钠因子（0.01 - 0.1 μM）具有抑制作用。因此，膜兴奋性的降低可能是一些增加细胞内环核苷酸水平的药物导致主动脉平滑肌舒张的一个促成因素。
