Coupar I M, Liu L
Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University, Parkville, Australia.
J Pharmacol Toxicol Methods. 1996 Nov;36(3):147-54. doi: 10.1016/s1056-8719(96)00110-4.
A tissue preparation is described which makes it possible to examine the effect of drugs on the nerves that control both longitudinal and circular muscles of the small intestine. The preparation consists of a segment of rat ileum set up to measure the tension developed in the longitudinal muscle and intraluminal pressure developed by the circular muscle in response to transmural electrical stimulation. The method showed that both muscles differed in their patterns of responses to transmural stimulation from the threshold of 2.5-60 Hz. All responses were tetrodotoxin-sensitive, the fast longitudinal muscle contraction and the intraluminal pressure response being caused by both pre- and postganglionic cholinergic nerves. The responses differed in their sensitivities to the alpha 2-adrenoceptor agonists clonidine and UK 14,304, whereby the cholinergic responses of the circular but not longitudinal muscle were inhibited by the agonists. Comparison of results with the guinea-pig ileum set up in the same way revealed a marked species variation in responses, in that the intraluminal pressure response of the guinea-pig ileum was not sensitive to alpha 2-adrenoceptor agonists. This clear species difference makes it possible to use the circular muscle of the rat ileum, as measured indirectly via intraluminal pressure, to assess compounds for activity at alpha 2-adrenoceptors over a wide range of frequencies.
本文描述了一种组织制备方法，该方法能够研究药物对控制小肠纵肌和环肌的神经的作用。该制备方法包括一段大鼠回肠，用于测量纵肌产生的张力以及环肌在跨壁电刺激下产生的腔内压力。该方法表明，在2.5 - 60Hz的阈值范围内，两种肌肉对跨壁刺激的反应模式不同。所有反应均对河豚毒素敏感，快速的纵肌收缩和腔内压力反应由节前和节后胆碱能神经引起。这些反应对α2 - 肾上腺素能受体激动剂可乐定和UK 14,304的敏感性不同，其中激动剂抑制环肌而非纵肌的胆碱能反应。将结果与以相同方式制备的豚鼠回肠进行比较，发现反应存在明显的物种差异，即豚鼠回肠的腔内压力反应对α2 - 肾上腺素能受体激动剂不敏感。这种明显的物种差异使得可以通过腔内压力间接测量大鼠回肠的环肌，以评估化合物在广泛频率范围内对α2 - 肾上腺素能受体的活性。
