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Identification of opioid receptors in the sympathetic and parasympathetic nerves of guinea‐pig atria
Author(s) -
Hung ChiFeng,
Chang WeiLuen,
Liang HsiuChuan,
Su MingJai
Publication year - 2000
Publication title -
fundamental and clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 73
eISSN - 1472-8206
pISSN - 0767-3981
DOI - 10.1111/j.1472-8206.2000.tb00420.x
Subject(s) - opioid receptor , opioid , medicine , endocrinology , (+) naloxone , stimulation , chemistry , agonist , receptor
— 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 OP 2 ‐opioid receptor agonists U‐50488 and U‐69593, but partly by the OP 3 ‐opioid receptor agonist morphine. This effect of U‐50488 and U‐69593 were reversed by the selective OP 2 ‐opioid receptor antagonist nor‐BNI. The effect of morphine was partly reversed by naloxone, whereas OP 1 ‐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 OP 2 ‐opioid receptor, however, the acetylcholine release from cardiac parasympathetic nerves is not modulated by opioid receptors.