title: Involvement of opioid mechanisms in peripheral motor control of detrusor muscle.
abstract: Isometric recordings of mechanical activity in muscle strips from rat and human detrusor were performed and the effect of mu- and delta-opioid receptor stimulation and blockade on detrusor contraction induced by electrical field stimulation was tested. Stimulation of the opioid mu-receptor with morphine (10(-13)-10(-4) M) and DAGO (10(-13)-10(-6) M) had no significant effect on electrical field stimulation except at one concentration of morphine (10(-6) M). Naloxone (10(-10)-10(-5) M) caused a significant facilitation of the electrical field stimulation-induced contraction, which was counteracted by morphine (10(-8) M) and the delta-agonist DPDPE (10(-8) M) in both rat and human detrusor. Addition of atropine (10(-6) M) or hexamethonium chloride (10(-6) M) or spantide (10(-6) M) did not alter the facilitating effect of naloxone in the rat detrusor. Hexamethonium (10(-5) M) decreased the facilitating effect of naloxone on electrical field stimulation-induced contractions in the human detrusor, indicating involvement of ganglionic mechanisms. In human detrusor about 15% of the contractile response was found to be atropine-resistant (10(-6) M) and one third of this was found to be resistant to tetrodotoxin (1.5 x 10(-6) M). The atropine resistant-response in human detrusor was facilitated by naloxone to the same extent as the atropine-sensitive part. Adrenergic blockade per se, achieved with phentolamine mesylate (10(-6) M) and propranolol (10(-6) M), caused a significant facilitation of the electrical field stimulation-induced contraction in the rat detrusor but did not affect the facilitating effect of naloxone (10(-13)-10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004745:Enkephalins / Q000494:pharmacology; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009019:Morphinans / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives*; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000187:drug effects / Q000502:physiology*; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D013565:Sympatholytics / Q000494:pharmacology
chemical_list: D004745:Enkephalins; D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D007211:Indoles; D009019:Morphinans; D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D013565:Sympatholytics; D013373:Substance P; D009270:Naloxone; D018738:Hexamethonium; D009271:Naltrexone; D009020:Morphine; C042867:spantide; C055382:naltrindole