Magaribuchi T, Nakajima H, Kiyomoto A
Jpn J Pharmacol. 1977 Jun;27(3):361-9. doi: 10.1254/jjp.27.361.
Effects of diltiazem on electrical and mechanical activities of isolated guinea pig taenia coli were studied by means of the double sucrose-gap method. In the spontaneously active preparations, diltiazem (2.2 X 10(-6) M) suppressed both electrical activity and isometric contraction, while electrical and mechanical activities evoked by the depolarizing current pulse were not affected at the concentration of 2.2 X 10(-6) M. In the presence of 2.2 X 10(-5) M diltiazem, the evoked contractile force and the number of repetitive firings during depolarization were reduced, whereas the single spike was almost unchanged or somewhat inhibited. At 2.2 X 10(-4) M diltiazem, both electrical and mechanical activities were almost abolished. The contractile force and single spike suppressed by diltiazem were partly reversed by the addition of 5 mM CaCl2. There was little significant change in membrane potential and membrane resistance. Similar but somewhat weaker effects were observed when NaCl was replaced with sucrose. In some preparations, 2.2 X 10(-4) M diltiazem reduced the contractile force without significant influence on the electrical activity in Na+-free Locke solution. CoCl2 (3 mM) inhibited the evoked activities in both normal and Na+-free solutions. Possible mechanisms for the relaxing effects of diltiazem on isolated guinea pig taenia coli were discussed.
采用双蔗糖间隙法研究了地尔硫䓬对豚鼠离体结肠带电活动和机械活动的影响。在自发活动的标本中，地尔硫䓬（2.2×10⁻⁶ M）可抑制电活动和等长收缩，而在2.2×10⁻⁶ M浓度下，去极化电流脉冲诱发的电活动和机械活动不受影响。在2.2×10⁻⁵ M地尔硫䓬存在时，诱发的收缩力和去极化期间的重复放电次数减少，而单个动作电位几乎不变或略有抑制。在2.2×10⁻⁴ M地尔硫䓬时，电活动和机械活动几乎完全消失。加入5 mM氯化钙可部分逆转地尔硫䓬抑制的收缩力和单个动作电位。膜电位和膜电阻几乎没有显著变化。用蔗糖代替氯化钠时观察到类似但稍弱的效应。在一些标本中，在无钠的洛克溶液中，2.2×10⁻⁴ M地尔硫䓬降低了收缩力，但对电活动没有显著影响。3 mM氯化钴抑制正常溶液和无钠溶液中诱发的活动。讨论了地尔硫䓬对豚鼠离体结肠带舒张作用的可能机制。
