Dale M M, Muid R
J Pharm Pharmacol. 1978 May;30(5):297-300. doi: 10.1111/j.2042-7158.1978.tb13233.x.
The guinea-pig isolated cremaster muscle gave tetrodotoxin-resistant dose-related contractures with acetylcholine, carbachol and the depolarizing neuromuscular blocking agents. The dose-response curve to suxamethonium in tetrodotoxin 2 X 10(-7)M could be shifted to the right with tubocurarine 10(-6)M. KCl, 0.1M, produced slow sustained contractures of the muscle. With the cremaster nerve-muscle preparation tetanic contractions at 20 Hz were maintained over several minutes. Tetrodotoxin eliminated the twitch response to single shock nerve stimulation but not the sustained increase in tension produced by suxamethonium. The results suggest either that there is a component of slow tonic muscle in the guinea-pig cremaster or that the cremaster consists of a type of focally innervated muscle which has pharmacological responses qualitatively different from those of most focally innervated muscles so far described.
豚鼠离体提睾肌对乙酰胆碱、卡巴胆碱及去极化型神经肌肉阻滞剂产生与剂量相关的、对河豚毒素有抗性的挛缩。在2×10⁻⁷M河豚毒素存在的情况下，对琥珀酰胆碱的剂量-反应曲线可被10⁻⁶M筒箭毒碱右移。0.1M氯化钾可使该肌肉产生缓慢持续的挛缩。对于提睾神经-肌肉标本，20Hz的强直收缩可维持数分钟。河豚毒素消除了对单刺激神经刺激的抽搐反应，但未消除琥珀酰胆碱引起的张力持续增加。结果表明，要么豚鼠提睾肌中存在慢张力肌成分，要么提睾肌由一种局部受神经支配的肌肉类型组成，其药理学反应在性质上与迄今所描述的大多数局部受神经支配的肌肉不同。
