Kennedy C, Burnstock G
J Pharm Pharmacol. 1986 Apr;38(4):307-9. doi: 10.1111/j.2042-7158.1986.tb04574.x.
Superfusion of the portal vein of rat and guinea-pig with Krebs' solution maintained at 25 degrees C greatly inhibits spontaneous contractions of the preparations and allows contractile responses to ATP and noradrenaline to be measured accurately. Under these conditions, continuous superfusion with ATP (10(-5) M), a concentration which had no effect on either basal tension or spontaneous activity, caused a significant shift to the left of the concentration-response curve to exogenous noradrenaline in both tissues. The mechanism of this potentiation induced by ATP may differ in the two tissues since in the rat portal vein potentiation appeared to be rapidly reversed by superfusing with ATP-free solution, whereas in the guinea-pig portal vein a further concentration-response curve to noradrenaline, in the absence of ATP, was still significantly shifted to the left compared with the control curve. However, potentiation in the rat portal vein may have had a longer duration than is suggested by the results since control concentration-response curves to noradrenaline in this tissue showed a progressive shift to the right which, although not significant, is likely to have affected the apparent time course of potentiation. It is concluded that ATP can potentiate contractions to exogenous noradrenaline in the portal vein of rat and guinea-pig via an, as yet, unidentified postjunctional mechanism.
用25℃的克雷布斯溶液对大鼠和豚鼠的门静脉进行灌流，可极大地抑制标本的自发收缩，并能准确测量对ATP和去甲肾上腺素的收缩反应。在这些条件下，用ATP（10⁻⁵M）持续灌流，该浓度对基础张力或自发活动均无影响，但却使两种组织中外源性去甲肾上腺素的浓度-反应曲线显著左移。ATP诱导的这种增强作用机制在两种组织中可能不同，因为在大鼠门静脉中，用无ATP溶液灌流似乎可迅速逆转增强作用，而在豚鼠门静脉中，在无ATP的情况下，去甲肾上腺素的另一浓度-反应曲线与对照曲线相比仍显著左移。然而，大鼠门静脉中的增强作用持续时间可能比结果显示的更长，因为该组织中去甲肾上腺素的对照浓度-反应曲线显示出逐渐右移，尽管不显著，但可能影响了增强作用的表观时间进程。结论是，ATP可通过一种尚未明确的接头后机制增强大鼠和豚鼠门静脉对外源性去甲肾上腺素的收缩作用。
