Wali F A
Pharmacol Res Commun. 1985 Feb;17(2):137-47. doi: 10.1016/0031-6989(85)90060-8.
The effect of substance P (SP) on the electrical and contractile responses of skeletal muscles of frog, chick and rat were studied using electrophysiological techniques. In low concentrations, SP increased the amplitude of twitch and tetanic contractions in response to motor nerve stimulation of frog, chick and rat preparations, increased the amplitude and duration of frog sciatic nerve compound action potential and reduced the contracture responses produced by acetylcholine (ACh) or tetraethylammonium (TEA) in the chick skeletal muscle. In all these actions, the effect of SP was calcium-dependent. The results provide evidence that SP had a dual action; a prejunctional facilitatory effect by causing a further release of ACh and/or Ca2+ entry or release, and postjunctional effect by reducing the sensitivity of the postjunctional membrane to depolarizing drugs.
运用电生理技术研究了P物质（SP）对青蛙、小鸡和大鼠骨骼肌电反应及收缩反应的影响。在低浓度下，SP可增强青蛙、小鸡和大鼠标本在运动神经刺激下的单收缩和强直收缩幅度，增加青蛙坐骨神经复合动作电位的幅度和时程，并减弱乙酰胆碱（ACh）或四乙铵（TEA）在小鸡骨骼肌中引起的挛缩反应。在所有这些作用中，SP的效应均依赖于钙。这些结果证明SP具有双重作用：一种是通过促使ACh进一步释放和/或Ca²⁺内流或释放而产生的突触前易化作用，另一种是通过降低突触后膜对去极化药物的敏感性而产生的突触后作用。
