Feldman P D, Moises H C
Department of Physiology, University of Michigan, Ann Arbor 48109.
Am J Physiol. 1988 Apr;254(4 Pt 2):H756-62. doi: 10.1152/ajpheart.1988.254.4.H756.
The effects of microiontophoresis of norepinephrine and epinephrine were examined on the spontaneous neuronal activity of single neurons in the nucleus tractus solitarius (NTS) in urethan-anesthetized rats. Neuronal responses to catecholamine iontophoresis were examined in the absence and presence of the alpha 1-adrenergic antagonist, prazosin, and the alpha 2-antagonist, idazoxan, to characterize the subtypes of alpha-adrenergic receptors mediating catecholamine action in this important autonomic nucleus. Norepinephrine produced inhibitions in firing, which were blocked primarily by idazoxan, whereas epinephrine-induced neuronal inhibitions were blocked by either prazosin or idazoxan. Inhibitions of spontaneous firing were also produced by iontophoresis of methoxamine, an alpha 1-selective agonist, or the alpha 2-selective agonist clonidine in all neurons that were tested. Neuronal responses to methoxamine were blocked selectively by prazosin, whereas the effects of clonidine were antagonized selectively by idazoxan. These data provide evidence at the level of the single unit that catecholamines may affect activity in the NTS via interactions with both alpha 1- and alpha 2-adrenergic receptors.
研究了去甲肾上腺素和肾上腺素微离子透入对乌拉坦麻醉大鼠孤束核（NTS）单个神经元自发神经活动的影响。在不存在和存在α1肾上腺素能拮抗剂哌唑嗪以及α2拮抗剂咪唑克生的情况下，检测神经元对儿茶酚胺离子透入的反应，以表征介导儿茶酚胺在这个重要自主神经核中发挥作用的α肾上腺素能受体亚型。去甲肾上腺素引起放电抑制，主要被咪唑克生阻断，而肾上腺素诱导的神经元抑制则被哌唑嗪或咪唑克生阻断。在所有测试的神经元中，α1选择性激动剂甲氧明或α2选择性激动剂可乐定的离子透入也产生自发放电抑制。神经元对甲氧明的反应被哌唑嗪选择性阻断，而可乐定的作用被咪唑克生选择性拮抗。这些数据在单个神经元水平上提供了证据，表明儿茶酚胺可能通过与α1和α2肾上腺素能受体相互作用来影响NTS中的活动。
