Burdyga T V, Magura I S
Gen Physiol Biophys. 1986 Dec;5(6):581-91.
The effects of caffeine on the electrical and mechanical activity of the guinea-pig ureter smooth muscle were studied. Under untreated conditions caffeine mainly showed inhibitory action on the ureter, inhibiting the evoked action potentials and phasic contractions as well as potassium contracture. Caffeine was also found to suppress the low-Na contracture of Na-loaded ureter muscle. It is established that Na-loaded tissue is able to generate transient contracture in response to caffeine application at 37 degrees C. These caffeine contractures could be evoked under completely removed [Ca2+]0 and in the presence of high doses of Ca-channel blockers (nifedipine, diltiazem, Mn ions) and could be reversibly blocked by tetracaine, procaine and benzocaine. Caffeine contractures could also be produced by the ureter muscle placed in isotonic K-solution. Cooling significantly potentiated low-Na, potassium and caffeine contractures of the ureter muscle. Filling of the store is totally dependent on the entry of Ca ions from the extracellular Ca2+ store sites which sequester Ca ions entering the cell on either Na-Ca exchange or via voltage operated Ca channels.
研究了咖啡因对豚鼠输尿管平滑肌电活动和机械活动的影响。在未处理的情况下，咖啡因主要对输尿管表现出抑制作用，抑制诱发的动作电位、相位收缩以及钾挛缩。还发现咖啡因能抑制钠负荷输尿管肌肉的低钠挛缩。已证实，钠负荷组织在37℃时对咖啡因的应用能产生短暂挛缩。这些咖啡因挛缩可在完全去除[Ca2+]0的情况下以及在高剂量钙通道阻滞剂（硝苯地平、地尔硫䓬、锰离子）存在时诱发，并可被丁卡因、普鲁卡因和苯佐卡因可逆性阻断。置于等渗钾溶液中的输尿管肌肉也可产生咖啡因挛缩。冷却显著增强了输尿管肌肉的低钠、钾和咖啡因挛缩。储存库的充盈完全依赖于细胞外钙储存部位的钙离子内流，这些部位通过钠钙交换或电压门控钙通道隔离进入细胞的钙离子。
