Mukumov M R, Khodorova A B, Khodorov B I
Fiziol Zh SSSR Im I M Sechenova. 1984 Feb;70(2):180-5.
Application of 12-24 mM caffeine-sodium bensoate (CFB) to the strip of frog ventricular or atrium myocardium in the tonic phase of K-contracture (200 mM KCl) produced a biphasic change of its isometric tension (P): first the rise and then the gradual decay to the "zero" level of P in the control Ringer's solution. A comparison of CFB effect with those of caffeine-base (CF) and sodium bensoate suggests that the first phase of CFB action (increase of P) results from the effect of CF, while the second one (fall of P) is due to the relaxing action of bensoate. Addition of 2 mM tetracaine to the K-rich solution in the tonic phase of K-contracture increases P and totally abolishes the first phase of the CFB effect, whereas the second one remains unchanged. Na-bensoate (12-24 mM) applied during the action of tetracaine induces relaxation of the strip to zero level of P. Blockade of Ca channels by 2.10(-6)-4.10(-5) g/ml D-600 or Bay-1040 does not affect the biphasic action of CFB. The dual CFB effect on the depolarized frog myocardium seems to be due to Ca ions release from the intracellular stores (action of CF) and to an inhibition of the voltage-dependent Ca influx via Na-Ca exchange mechanism (action of bensoate).
在钾收缩（200 mM KCl）的强直期，将12 - 24 mM的咖啡因苯甲酸钠（CFB）应用于蛙心室或心房心肌条时，其等长张力（P）会出现双相变化：首先升高，然后在对照任氏液中逐渐衰减至P的“零”水平。将CFB的作用与咖啡因碱（CF）和苯甲酸钠的作用进行比较表明，CFB作用的第一阶段（P增加）是由CF的作用引起的，而第二阶段（P下降）则是由于苯甲酸盐的舒张作用。在钾收缩的强直期，向富含钾的溶液中添加2 mM丁卡因会增加P，并完全消除CFB作用的第一阶段，而第二阶段保持不变。在丁卡因作用期间应用苯甲酸钠（12 - 24 mM）可使心肌条松弛至P的零水平。用2×10⁻⁶ - 4×10⁻⁵ g/ml的D - 600或Bay - 1040阻断钙通道并不影响CFB的双相作用。CFB对去极化蛙心肌的双重作用似乎是由于细胞内钙库释放钙离子（CF的作用）以及通过钠钙交换机制抑制电压依赖性钙内流（苯甲酸盐的作用）。
