α-和β-肾上腺素能受体激活对鸡直肠纵行平滑肌张力和膜特性的影响。

The effects of alpha- and beta-adrenoceptor activation on tension and membrane properties of the longitudinal smooth muscle of the chicken rectum.

Komori S, Ohashi H, Takewaki T

Br J Pharmacol. 1980;71(2):479-88. doi: 10.1111/j.1476-5381.1980.tb10961.x.

Abstract

Isolated longitudinal muscle strips from the chicken rectum responded to isoprenaline, adrenaline and noradrenaline with a prolonged relaxation. The concentrations required to produce 50% of the maximum relaxation were 1.3 x 10(-8) M for isoprenaline, 1.7 x 10(-8) M for adrenaline and 10(-6) M for noradrenaline. The relaxing potency of isoprenaline is about equal to that of adrenaline, but more than 50 times that of noradrenaline. 2. Propranolol, 3.4 x 10(-6) M, blocked the isoprenaline-induced relaxation, and in the presence of this drug the responses to adrenaline and noradrenaline were converted into small, transient relaxations. The residual relaxation was blocked by phentolamine, 2.6 x 10(-6) M. 3. These catecholamines suppressed spontaneous spike discharge and produced membrane hyperpolarization. Propranolol, 3.4 x 10(-6) M, prevented the inhibitory effects of isoprenaline, and reduced but did not completely abolish those of adrenaline and noradrenaline. 4. Adrenaline and noradrenaline, but not isoprenaline, reduced membrane resistance in some preparations. 5. In the rectal muscle of the chicken, the beta-adrenoceptor mediates a prolonged relaxation and the alpha-adrenoceptor a fast and short-lasting relaxation which is usually obscured by the beta-response and unmasked only after blockade of the beta-adrenoceptors. The alpha- and beta-mediated relaxations are each associated with the suppression of spontaneous spike activity.

摘要

从鸡直肠分离出的纵行肌条对异丙肾上腺素、肾上腺素和去甲肾上腺素产生长时间的舒张反应。产生最大舒张反应50%所需的浓度，异丙肾上腺素为1.3×10⁻⁸ M，肾上腺素为1.7×10⁻⁸ M，去甲肾上腺素为10⁻⁶ M。异丙肾上腺素的舒张效力约与肾上腺素相等，但比去甲肾上腺素大50倍以上。2. 3.4×10⁻⁶ M的普萘洛尔阻断了异丙肾上腺素诱导的舒张，在该药物存在的情况下，对肾上腺素和去甲肾上腺素的反应转变为小的、短暂的舒张。残余的舒张被2.6×10⁻⁶ M的酚妥拉明阻断。3. 这些儿茶酚胺抑制自发性锋电位发放并产生膜超极化。3.4×10⁻⁶ M的普萘洛尔阻止了异丙肾上腺素的抑制作用，并减弱了肾上腺素和去甲肾上腺素的抑制作用，但并未完全消除。4. 肾上腺素和去甲肾上腺素，但不是异丙肾上腺素，在某些制剂中降低膜电阻。5. 在鸡的直肠肌中，β-肾上腺素能受体介导长时间舒张，α-肾上腺素能受体介导快速且短暂的舒张，这种舒张通常被β反应掩盖，只有在β-肾上腺素能受体被阻断后才会显现出来。α和β介导的舒张均与自发性锋电位活动的抑制有关。