title: The effect of opioids on rat plasma atrial natriuretic peptide.
abstract: The effect of multiple opioid receptor agonists on plasma immunoreactive atrial natriuretic factor (IR-ANF) was studied in conscious non-hydrated rats. We found that mu-opioid receptor agonists, given subcutaneously, increased plasma IR-ANF, while kappa-receptor agonists did not alter the plasma levels of IR-ANF. The mu-agonist fentanyl (0.05 mg/kg) caused a 10-fold increase in the concentration of IR-ANF, maximal levels being reached within 5-10 min. U 50,488-H and ethylketocyclazocine (EKC), both selective kappa-receptor ligands, were ineffective in this respect. The effect of fentanyl upon plasma IR-ANF was completely abolished by pretreatment with the narcotic antagonist naltrexone, proving opioid receptor specificity of the fentanyl effect. The quaternary antagonist N-methylnaltrexone (1 mg/kg) failed to block the fentanyl-induced increase of ANF, suggesting that opiates bring about their action on ANF via a central mechanism.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005283:Fentanyl / Q000494:pharmacology; D008297:Male; D009271:Naltrexone / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000596:Amino Acids; D009294:Narcotics; D009271:Naltrexone; D009320:Atrial Natriuretic Factor; D003000:Clonidine; D005283:Fentanyl