Gregory P C
J Physiol. 1984 Jan;346:379-93. doi: 10.1113/jphysiol.1984.sp015029.
The intrinsic motility of the reticulo-rumen was studied by electromyography in nineteen sheep subjected to bilateral thoracic vagotomy and maintained by intragastric infusion of a complete liquid diet. The influences of distension, temperature and tactile and chemical stimuli on the intrinsic reticulo-ruminal motility were investigated. The level of electrical discharge in the reticulum and rumen in the first 3 days after vagotomy was increased progressively with distension without giving rise to the large group discharges characteristic of the long-term vagotomized sheep, and was reduced by atropine (0.1-1 mg kg-1) but not by hexamethonium (2 mg kg-1). In the long-term vagotomized animals, the frequency of the large group discharges over the reticulo-rumen varied with the degree of reticulo-ruminal distension. The discharges were absent below a threshold rumen volume; above the threshold they increased progressively with volume until a maximal rate of six to seven regular discharges per minute was established at large ruminal volumes. The discharges were abolished by atropine (0.1-1 mg kg-1) or hexamethonium (2 mg kg-1). With the rumen volume below the threshold, in all areas of the reticulo-rumen localized distension stimulated local discharge only and did not induce large group discharge. Replacement of rumen contents with an equal volume of 0.2 M-acetic, -propionic or -butyric acid buffered to pH 4.0 rapidly abolished the large group discharges over the entire reticulo-rumen. Replacement of rumen contents by an equal volume of 0.9% NaCl at 30 degrees C immediately abolished the large group discharges; at temperatures between 35 and 43 degrees C this had no effect. Gentle tactile stimulation increased local discharge in the reticulum and cranial dorsal sac but not in other areas of the rumen and did not affect large group discharge in any region. It is concluded that the intrinsic reticulo-ruminal motility of chronically vagotomized sheep is principally regulated by the degree of reticulo-ruminal distension. Like the C.N.S.-controlled motility of the vagus-intact sheep it is inhibited by high concentrations of volatile fatty acids. Local control mechanisms therefore may interact with central control in the over-all regulation of motility in vagus-intact sheep.
通过肌电图研究了19只双侧胸段迷走神经切断并通过胃内输注完全液体饮食维持的绵羊瘤网胃的内在运动性。研究了扩张、温度以及触觉和化学刺激对瘤网胃内在运动性的影响。迷走神经切断后前3天瘤网胃的放电水平随着扩张而逐渐增加，但未引发长期迷走神经切断绵羊特有的大量群放电，且阿托品（0.1 - 1毫克/千克）可使其降低，而六甲铵（2毫克/千克）则无此作用。在长期迷走神经切断的动物中，瘤网胃上大量群放电的频率随瘤网胃扩张程度而变化。瘤胃容积低于阈值时无放电；高于阈值时，放电随容积逐渐增加，直至瘤胃容积较大时达到每分钟6至7次规则放电的最大速率。阿托品（0.1 - 1毫克/千克）或六甲铵（2毫克/千克）可消除放电。当瘤胃容积低于阈值时，在瘤网胃的所有区域，局部扩张仅刺激局部放电，不会诱发大量群放电。用等体积pH值为4.0的0.2M乙酸、丙酸或丁酸缓冲液替代瘤胃内容物可迅速消除整个瘤网胃上的大量群放电。用等体积30℃的0.9%氯化钠替代瘤胃内容物可立即消除大量群放电；在35至43℃之间的温度下则无此作用。轻柔的触觉刺激可增加瘤胃的局部放电，但在瘤胃的其他区域则无此作用，且不影响任何区域的大量群放电。结论是慢性迷走神经切断绵羊的瘤网胃内在运动性主要受瘤网胃扩张程度的调节。与迷走神经完整绵羊受中枢神经系统控制的运动性一样，高浓度挥发性脂肪酸可抑制其运动性。因此，在迷走神经完整绵羊运动性的整体调节中，局部控制机制可能与中枢控制相互作用。
