Ha J H, Lee K Y, Kim W J
Department of Pharmacology, Yeungnam University, College of Medicine, Taegu, Korea.
J Korean Med Sci. 1993 Feb;8(1):53-9. doi: 10.3346/jkms.1993.8.1.53.
This study was performed to investigate the action of potassium channel openers on the mechanical activity of detrusor muscle isolated from rats. Detrusor muscle strips, 15 mm in length, were myographied isometrically in an isolated organ bath. P 1060, RP 49356 and BRL 38277, potassium channel activators, reduced the basal tone and diminished the phasic activity of detrusor concentration-dependently. P 1060, RP 49356 and BRL 38227 suppressed the maximal responses to bethanechol and shifted the concentration-response curves of bethanechol-induced contraction to the right. RP 49356 and BRL 38227 reduced the contraction by low (20 mM) concentration of potassium. P 1060, however, diminished the high (80 mM) and low (20 mM) concentration of potassium-induced contraction. Glibenclamide, an inhibitor of ATP-dependent potassium channel, antagonized the suppressive action of P 1060, RP 49356 and BRL 38227 on the basal tone. Apamin or procaine did not antagonize it significantly. Based on these results, it is suggested that the relaxation of detrusor muscle strip caused by P 1060, RP 49356 and BRL 38227 may predominantly involve opening of the same potassium channel, i.e., the ATP-dependent potassium channel.
本研究旨在探讨钾通道开放剂对大鼠离体逼尿肌机械活性的作用。将长度为15毫米的逼尿肌条在离体器官浴槽中进行等长肌动描记。钾通道激活剂P 1060、RP 49356和BRL 38277浓度依赖性地降低了逼尿肌的基础张力并减弱了其相性活动。P 1060、RP 49356和BRL 38227抑制了对氨甲酰甲胆碱的最大反应，并使氨甲酰甲胆碱诱导收缩的浓度-反应曲线右移。RP 49356和BRL 38227降低了低浓度（20 mM）钾引起的收缩。然而，P 1060减弱了高浓度（80 mM）和低浓度（20 mM）钾诱导的收缩。格列本脲，一种ATP依赖性钾通道抑制剂，拮抗了P 1060、RP 49356和BRL 38227对基础张力的抑制作用。蜂毒明肽或普鲁卡因对此没有明显拮抗作用。基于这些结果，提示P 1060、RP 49356和BRL 38227引起的逼尿肌条松弛可能主要涉及同一钾通道即ATP依赖性钾通道的开放。
