Cunnane T C, Muir T C, Wardle K A
Department of Pharmacology, University of Glasgow.
Br J Pharmacol. 1987 Sep;92(1):39-46. doi: 10.1111/j.1476-5381.1987.tb11293.x.
1 Electrical and mechanical responses to field (transmural) and extrinsic nerve stimulation were recorded simultaneously in the rat anococcygeus muscle. Membrane potential changes recorded intracellularly following either method of stimulation were indistinguishable. Single stimuli usually produced a slow depolarization; trains of pulses produced a fast excitatory junction potential (e.j.p.) initially, followed by a slow depolarization similar to that produced by single pulses. The fast e.j.ps, the slow depolarizations and the accompanying contractions were abolished by the alpha-adrenoceptor antagonists, phentolamine (1 X 10(-6)M) or prazosin (1 X 10(-7)M) and by tetrodotoxin (TTX, 1 X 10(-6)M) but unaffected by alpha, beta-methylene adenosine triphosphate (alpha, beta-MeATP, 1(-10) X 10(-6)M), an agent known to desensitize purinoceptors. 2 Application of noradrenaline (NA, 1 X 10(-8)-1 X 10(-6)M), by pressure ejection from a micropipette, depolarized the membrane and produced a localized contraction, both of which were abolished by phentolamine (1 X 10(-6)M) or prazosin (1 X 10(-7)M). 3 Application of adenosine-5'-triphosphate (ATP, 1 X 10(-4)-1 X 10(-3)M), by pressure ejection from a micropipette, produced a small membrane depolarization and localized contraction which were unaffected by phentolamine (1 X 10(-6)M) or prazosin (1 X 10(-7)M) but abolished by alpha, beta-MeATP (1 X 10(-6)M). 4 The results show that, in the rat annococcygeus muscle, (1) field or extrinsic nerve stimulation released only one excitatory transmitter, namely NA, although receptors for both NA and ATP were present on the muscle, (2) alpha, beta-MeATP was selective for purinoceptors and (3) there was no evidence for excitatory co-transmission in this tissue.
在大鼠肛门尾骨肌中，同时记录了对场（跨膜）刺激和外在神经刺激的电反应和机械反应。通过两种刺激方法记录的细胞内膜电位变化没有区别。单个刺激通常会产生缓慢的去极化；脉冲串最初会产生快速兴奋性接头电位（e.j.p.），随后是类似于单个脉冲产生的缓慢去极化。快速e.j.p.、缓慢去极化以及伴随的收缩可被α-肾上腺素能受体拮抗剂酚妥拉明（1×10⁻⁶M）或哌唑嗪（1×10⁻⁷M）以及河豚毒素（TTX，1×10⁻⁶M）消除，但不受α,β-亚甲基三磷酸腺苷（α,β-MeATP，1×10⁻⁶M）的影响，α,β-MeATP是一种已知能使嘌呤受体脱敏的药物。
通过微量移液器压力喷射施加去甲肾上腺素（NA，1×10⁻⁸ - 1×10⁻⁶M），使膜去极化并产生局部收缩，这两者都可被酚妥拉明（1×10⁻⁶M）或哌唑嗪（1×10⁻⁷M）消除。
通过微量移液器压力喷射施加三磷酸腺苷（ATP，1×10⁻⁴ - 1×10⁻³M），产生小的膜去极化和局部收缩，这两者不受酚妥拉明（1×10⁻⁶M）或哌唑嗪（1×10⁻⁷M）的影响，但可被α,β-MeATP（1×10⁻⁶M）消除。
结果表明，在大鼠肛门尾骨肌中，（1）场刺激或外在神经刺激仅释放一种兴奋性递质，即NA，尽管肌肉上同时存在NA和ATP的受体，（2）α,β-MeATP对嘌呤受体具有选择性，（3）没有证据表明该组织中存在兴奋性共传递。
