title: Identification and localization of opioid receptors in the opossum lower esophageal sphincter.
mesh_terms: D000818:Animals; D004943:Esophagogastric Junction / Q000187:drug effects*; D005260:Female; D008297:Male; D008614:Meperidine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009893:Opossums; D011957:Receptors, Opioid / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D009294:Narcotics; D011957:Receptors, Opioid; D009270:Naloxone; D008614:Meperidine