This study was designed to investigate the effects of polyamines on mechanical contraction and voltage-dependent calcium current (VDCC) of guinea-pig gastric smooth muscle. Mechanical contraction and calcium channel current ( I Ba) were recorded by isometric tension recording and whole-cell patch clamp technique. Spermine, spermidine and putrescine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner. Spermine (2 mM) reduced high K+ (50 mM)-induced contraction to 16±6.4% of the control (n=9), and significantly inhibited I Ba in a reversible manner ( p 50=0.8 mM). Pre- and post-treatment of tissue with spermine (2-5 mM, n=10) also inhibited acetylcholine (10 μM)-induced phasic contraction to 5±6.4% of the control. Inhibitory effect of spermine on I Ba was observed at a wide range of test potentials of current/voltage ( I/V ) relationship ( p Ba was shifted to the right by spermine ( p Ba to 51±5.7% and 81±5.3% of the control, respectively. And putrescine (1 mM) inhibited I Ba at whole tested potentials ( p +-induced contraction to 53±7.1% of the control (n=4). These findings suggest that polyamines inhibit contractions of guinea-pig gastric smooth muscle via inhibition of VDCC.
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机译：这项研究旨在调查多胺对豚鼠胃平滑肌的机械收缩和电压依赖性钙电流（VDCC）的影响。通过等距张力记录和全细胞膜片钳技术记录机械收缩和钙通道电流（I Ba ）。精胺，亚精胺和腐胺以浓度依赖性方式抑制胃平滑肌的自发收缩。精胺（2 mM）将高K + （50 mM）引起的收缩降低至对照组的16±6.4％（n = 9），并显着抑制I Ba 可逆方式（p 50 = 0.8 mM）。用精胺（2-5 mM，n = 10）对组织进行预处理和后处理也将乙酰胆碱（10μM）诱导的相收缩抑制至对照组的5±6.4％。在大范围的电流/电压（I / V）关系测试电位下，观察到精胺对I Ba 的抑制作用（p Ba 被精胺向右移动（p Ba 分别达到对照组的51±5.7％和81±5.3％。腐胺（1 mM）在整个测试电位下均抑制了I Ba （p + 诱导的收缩达到对照组的53±7.1％（n = 4），这些发现表明多胺通过抑制VDCC抑制豚鼠胃平滑肌的收缩。
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