[Effect of agonists of opioid receptor on coronary arterial strips in porcine].

Bioassay of spiral strips was used to study the effect of agonists of opioid receptor on coronary artery strips of porcine. It was found that selective agonist of kappa (U-50488H), mu (ohmefentanyl OMF) and delta (morphine and DADLE) receptor and wide spectrum agonist of opioid receptor etorphine all produced the contraction of strips dose-dependently. The order of the effect was U-50488H > morphine > etorphine > OMF, DADLE. Naloxone did not antagonize but increase the effect, or even produce contraction of the strips by itself. Haloperidol inhibited the contraction of the strip produced by U-50488H noncompetitively, also in a dose-dependent manner, probably without involving dopamine mechanism. The results indicated that kappa subtype is chiefly involved in the contraction of porcine coronary artery. The conclusion agrees with our autoradiography study of opioid receptor in porcine coronary artery.