Gibson A, Yu O
Br J Pharmacol. 1983 Jun;79(2):611-5. doi: 10.1111/j.1476-5381.1983.tb11036.x.
Trains of field stimulation of 60 s duration caused a biphasic relaxation of carbachol (50 microM)-induced tone in the mouse anococcygeus. The optimal pulse frequency and width were 10 Hz and 1 ms respectively. Tetrodotoxin (31, 124, and 310 nM) caused a dose-dependent reduction in the magnitude of both phases. Neither phase was affected by (+/-)-propranolol (1 microM), neostigmine (1 microM), (+)-tubocurarine (100 microM), or apamin (500 nM). Biphasic relaxations were observed in muscles from 6-hydroxydopamine pretreated mice. Haemolysed blood (10, 40, and 100 microliter/ml) reduced the magnitude of the first phase of nerve-induced relaxation to a greater extent than the second. This effect was reversible. Following a prolonged train of inhibitory nerve stimulation (10 Hz; 10 min) the magnitude of the first phase was reduced only slightly, but the second markedly. The possible relationships between the biphasic relaxation to field stimulation and putative non-adrenergic, non-cholinergic transmitters in the mouse anococcygeus are discussed.
持续60秒的串刺激引起小鼠肛门尾骨肌中卡巴胆碱（50微摩尔）诱导的张力出现双相性松弛。最佳脉冲频率和宽度分别为10赫兹和1毫秒。河豚毒素（31、124和310纳摩尔）使两个相的幅度呈剂量依赖性降低。两个相均不受（±）-普萘洛尔（1微摩尔）、新斯的明（1微摩尔）、（+）-筒箭毒碱（100微摩尔）或蜂毒明肽（500纳摩尔）的影响。在6-羟基多巴胺预处理小鼠的肌肉中观察到双相性松弛。溶血血液（10、40和100微升/毫升）对神经诱导松弛第一相幅度的降低程度大于第二相。这种效应是可逆的。在长时间的抑制性神经刺激串（10赫兹；10分钟）后，第一相的幅度仅略有降低，但第二相明显降低。讨论了小鼠肛门尾骨肌中对场刺激的双相性松弛与假定的非肾上腺素能、非胆碱能递质之间的可能关系。
