Liang Y, Wu B W, Dun W
Department of Physiology, Shanxi Medical University, Taiyuan, China.
Zhongguo Yao Li Xue Bao. 1998 Mar;19(2):154-7.
To study the effect of phentolamine on L-type calcium currents (ICa) and ATP-sensitive K+ currents (IK,ATP) in ventricular myocytes.
ICa and IK,ATP were observed using patch clamp techniques in whole-cell recording configuration.
Phentolamine reduced ICa of ventricular myocytes in concentration-dependent and voltage-independent manners. Phentolamine 5, 25, and 100 mumol.L-1 decreased ICa from 370 +/- 99 nA to 310 +/- 95 nA (17% block, n = 6, P < 0.01), from 230 +/- 98 nA to 180 +/- 73 nA (23% block, n = 5, P < 0.05), and from 293 +/- 66 nA to 206 +/- 44 nA (30% block, n = 5, P < 0.01), respectively, without affecting the current-voltage relationship. Prazosin 100 mumol.L-1 and yohimbine 100 mumol.L-1, which were specific blockers of alpha 1 and alpha 2 adrenoceptors respectively, did not show the inhibitory effect on ICa. Phentolamine 100 mumol.L-1 also inhibited the IK,ATP induced by 2, 4-dinitrophenol (DNP) at 0 mV from 3.2 +/- 0.6 nA to 0.8 +/- 0.5 nA (75% block, n = 4, P < 0.01).
Phentolamine directly inhibits ICa and IK,ATP in guinea pig ventricular myocytes.
研究酚妥拉明对心室肌细胞L型钙电流（ICa）和ATP敏感性钾电流（IK,ATP）的影响。
采用膜片钳技术全细胞记录模式观察ICa和IK,ATP。
酚妥拉明以浓度依赖性和电压非依赖性方式降低心室肌细胞的ICa。5、25和100μmol.L-1的酚妥拉明分别使ICa从370±99 nA降至310±95 nA（阻断17%，n = 6，P < 0.01），从230±98 nA降至180±73 nA（阻断23%，n = 5，P < 0.05），从293±66 nA降至206±44 nA（阻断30%，n = 5，P < 0.01），且不影响电流-电压关系。分别作为α1和α2肾上腺素能受体特异性阻断剂的100μmol.L-1哌唑嗪和100μmol.L-1育亨宾对ICa无抑制作用。100μmol.L-1酚妥拉明还可抑制0 mV时2,4-二硝基苯酚（DNP）诱导的IK,ATP，使其从3.2±0.6 nA降至0.8±0.5 nA（阻断75%，n = 4，P < 0.01）。
酚妥拉明可直接抑制豚鼠心室肌细胞的ICa和IK,ATP。
