Hung C F, Chang W L, Liang H C, Su M J
Department of Pharmacology, College of Medicine, National Taiwan University, Taipei.
Fundam Clin Pharmacol. 2000 Jul-Aug;14(4):387-94. doi: 10.1111/j.1472-8206.2000.tb00420.x.
The opioid receptor subtypes of autonomic nerves of guinea-pig atria were elucidated by monitoring the effects of selective opioid receptor agonists on the negative and positive inotropic responses associated with the stimulation of the parasympathetic and sympathetic nerves, respectively. The positive inotropic effect, evoked by electrical field stimulation (2 Hz) was strongly reduced by the selective OP2-opioid receptor agonists U-50488 and U-69593, but partly by the OP3-opioid receptor agonist morphine. This effect of U-50488 and U-69593 were reversed by the selective OP2-opioid receptor antagonist nor-BNI. The effect of morphine was partly reversed by naloxone, whereas OP1-opioid receptor agonists, BW373 U86 and DPDPE, were ineffective. On the other hand, the negative inotropic response to electrical field stimulation was not affected by opioid receptor agonists. These results suggest that the noradrenaline release from cardiac sympathetic nerves of guinea-pig could be modulated, mainly by the OP2-opioid receptor, however, the acetylcholine release from cardiac parasympathetic nerves is not modulated by opioid receptors.
通过监测选择性阿片受体激动剂对分别与副交感神经和交感神经刺激相关的负性和正性变力反应的影响，阐明了豚鼠心房自主神经的阿片受体亚型。电场刺激（2Hz）诱发的正性变力作用被选择性OP2-阿片受体激动剂U-50488和U-69593强烈减弱，但被OP3-阿片受体激动剂吗啡部分减弱。U-50488和U-69593的这种作用被选择性OP2-阿片受体拮抗剂nor-BNI逆转。吗啡的作用被纳洛酮部分逆转，而OP1-阿片受体激动剂BW373 U86和DPDPE无效。另一方面，电场刺激引起的负性变力反应不受阿片受体激动剂的影响。这些结果表明，豚鼠心脏交感神经的去甲肾上腺素释放主要受OP2-阿片受体调节，然而，心脏副交感神经的乙酰胆碱释放不受阿片受体调节。
