Ueda N, Muramatsu I, Sakakibara Y, Fujiwara M
Jpn J Pharmacol. 1981 Dec;31(6):1071-9. doi: 10.1254/jjp.31.1071.
In the rabbit iris sphincter muscle, electrical transmural stimulation produced fast and slow components of contraction which were markedly attenuated by tetrodotoxin. The fast component was augmented by physostigmine and was abolished by atropine, while the slow component was little affected. Adrenergic and ganglionic blocking agents did not inhibit the slow component. Therefore, the fast component is probably cholinergic, while the slow one is noncholinergic, nonadrenergic in nature. Capsaicin did produce a considerable contractile response, but there was a gradual decline with repetitive application and a tachyphylaxis occurred. Under such conditions the slow but not the fast component was abolished. Substance P and acetylcholine produced the largest contraction, while ATP, histamine, serotonin and noradrenaline produced little or no response. In cold stored preparations, the responses to electrical transmural stimulation and capsaicin were either markedly attenuated or abolished, whereas substance P and acetylcholine produced considerable contractions. Baclofen and theophylline did not inhibit the slow response to electrical transmural stimulation or the response to substance P and capsaicin. Thus, electrical transmural stimulation produces cholinergic and noncholinergic, non-adrenergic contractions in the rabbit iris sphincter muscle and the latter response is considered to be mediated by substance P or a related peptide released from the neural component.
在兔虹膜括约肌中，经壁电刺激可产生快速和慢速收缩成分，河豚毒素可使其明显减弱。毒扁豆碱可增强快速成分，阿托品可消除快速成分，而慢速成分受影响较小。肾上腺素能和神经节阻断剂并不抑制慢速成分。因此，快速成分可能是胆碱能的，而慢速成分本质上是非胆碱能、非肾上腺素能的。辣椒素确实会产生相当大的收缩反应，但随着重复应用会逐渐下降，并出现快速耐受性。在这种情况下，慢速成分而非快速成分被消除。P物质和乙酰胆碱产生的收缩最大，而ATP、组胺、5-羟色胺和去甲肾上腺素几乎不产生反应或无反应。在冷藏制剂中，对经壁电刺激和辣椒素的反应要么明显减弱要么被消除，而P物质和乙酰胆碱则产生相当大的收缩。巴氯芬和茶碱并不抑制对经壁电刺激的慢速反应或对P物质和辣椒素的反应。因此，经壁电刺激可在兔虹膜括约肌中产生胆碱能和非胆碱能、非肾上腺素能收缩，后一种反应被认为是由神经成分释放的P物质或相关肽介导的。
