Moulds R F, Stevens M J
Gen Pharmacol. 1983;14(1):81-3. doi: 10.1016/0306-3623(83)90069-1.
The effects of beta-adrenoceptor agonists and antagonists on both the transmitter outflow and the associated pressure response produced by perivascular nerve stimulation have been studied in human digital arteries and metatarsal veins, in which transmitter stores were labelled with [3H]noradrenaline. Both isoprenaline in arteries, and salbutamol in arteries and veins, at concentrations of 10(-8) - 10(-6) mol/l significantly enhanced stimulation-induced tritium outflow. These two agonists were approximately equipotent. Salbutamol also potentiated pressure responses to stimulation, and propranolol prevented the enhancement of stimulation-induced tritium outflow by salbutamol. Adrenaline, at a concentration of 10(-8) mol/l, but not lower concentrations, significantly enhanced stimulation-induced tritium outflow in arteries. Propranolol, however, had no effect on stimulation-induced transmitter outflow, even when the arteries were either perfused throughout the experiment with a low concentration of adrenaline, or when the arteries were preincubated in a high concentration of adrenaline as well as perfused throughout with a low concentration of adrenaline. It is concluded that facilitatory prejunctional beta-adrenoceptors (probably of the beta 2-subtype) are present in human arteries and veins, but that under the conditions of these experiments, neither transmitter noradrenaline, nor adrenaline that has been incorporated into transmitter stores with noradrenaline, activate these prejunctional beta-adrenoceptors. They may, however, be activated under conditions of enhanced adrenomedullary secretion.
在人体指动脉和跖静脉中，研究了β-肾上腺素能受体激动剂和拮抗剂对血管周围神经刺激所产生的递质释放及相关压力反应的影响，其中递质储存用[3H]去甲肾上腺素进行标记。动脉中的异丙肾上腺素以及动脉和静脉中的沙丁胺醇，浓度在10⁻⁸ - 10⁻⁶mol/L时，均能显著增强刺激诱导的氚外流。这两种激动剂的效能大致相当。沙丁胺醇还能增强对刺激的压力反应，而普萘洛尔可阻止沙丁胺醇增强刺激诱导的氚外流。浓度为10⁻⁸mol/L的肾上腺素能显著增强动脉中刺激诱导的氚外流，但更低浓度则无此作用。然而，即使在整个实验过程中用低浓度肾上腺素灌注动脉，或动脉预先在高浓度肾上腺素中孵育并在整个过程中用低浓度肾上腺素灌注，普萘洛尔对刺激诱导的递质释放也没有影响。结论是，在人体动脉和静脉中存在易化性节前β-肾上腺素能受体（可能是β₂亚型），但在这些实验条件下，无论是递质去甲肾上腺素，还是已与去甲肾上腺素一起掺入递质储存中的肾上腺素，均不能激活这些节前β-肾上腺素能受体。不过，在肾上腺髓质分泌增强的条件下，它们可能被激活。
