Wang L, Cross A L, Allen K L, Smith B L, McLeay L M
Department of Biological Sciences, The University of Waikato, PB 3105, Hamilton, New Zealand.
Res Vet Sci. 2003 Feb;74(1):93-100. doi: 10.1016/s0034-5288(02)00153-4.
Reticulum and rumen strips (consisting of both muscle layers and the myenteric plexus) were superfused with Tyrode Ringer and their contractions recorded isometrically. The strips were subjected to exogenous acetylcholine and electrical field stimulation (EFS) resulting in contractions that could be blocked by atropine. Responses to the tremorgenic mycotoxin penitrem A and others thought to be involved in ryegrass staggers, paxilline and lolitrem B (10(-10)-10(-6)M), were compared with those of control vehicle (0.1% DMSO). The tremorgens were without effect on quiescent preparations. Penitrem A and paxilline enhanced spontaneously active preparations and the amplitude of contractions in response to EFS. Responses to paxilline had a shorter latency than to penitrem A. Responses of spontaneously active preparations were resistant to atropine. Penitrem A, but not paxilline, increased responses to exogenous acetylcholine. Lolitrem B (10(-6)M) increased responses to EFS, but many responses were equivocal, possibly due to the lower solubility of lolitrem B in aqueous solutions compared to the other tremorgens. The results show that these mycotoxins have peripheral excitatory effects on the reticulorumen and it is suggested that such activity in vivo may reflexly affect centrally derived cyclical contractions.
用台氏林格液对网胃和瘤胃肌条（由两层肌肉和肌间神经丛组成）进行灌流，并等长记录其收缩情况。给肌条施加外源性乙酰胆碱和电场刺激（EFS），可引发收缩，且该收缩可被阿托品阻断。将对震颤性霉菌毒素青霉震颤素A以及其他被认为与黑麦草中毒有关的毒素（如鬼笔环肽和洛利特菌素B，浓度为10⁻¹⁰ - 10⁻⁶M）的反应，与对照溶剂（0.1%二甲基亚砜）的反应进行比较。这些震颤剂对静止的标本没有作用。青霉震颤素A和鬼笔环肽增强了自发活动的标本以及对EFS的收缩幅度。对鬼笔环肽的反应潜伏期比对青霉震颤素A的短。自发活动标本的反应对阿托品有抗性。青霉震颤素A而非鬼笔环肽增加了对外源性乙酰胆碱的反应。洛利特菌素B（10⁻⁶M）增加了对EFS的反应，但许多反应不明确，这可能是由于洛利特菌素B在水溶液中的溶解度比其他震颤剂低。结果表明，这些霉菌毒素对网胃 - 瘤胃有外周兴奋作用，提示这种体内活性可能通过反射影响中枢源性的周期性收缩。
