title: Met-enkephalin-induced vasoconstriction in the microcirculation of rat striated muscle.
abstract: Sprague-Dawley rats were anesthetized with pentobarbital (50 mg/kg) and the arterioles of the cremaster muscle were observed using television microscopy. Methionine (Met)-enkephalin was added to give bath concentrations of 10(-11) to 10(-7) M. Met-enkephalin caused a decrease in the diameter of first-order (127 +/- 7 microns), second-order (57 +/- 7 microns), and third-order (18 +/- 2 microns) arterioles, with the third-order arterioles showing the greatest reactivity. The effects of Met-enkephalin were attenuated by the opiate antagonist, naloxone, by the alpha-adrenergic receptor antagonists, phentolamine and prazosin, and by chemical sympathectomy with 6-hydroxydopamine. These results suggest that Met-enkephalin causes vasoconstriction in the striated muscle microcirculation by stimulating norepinephrine release from local nerve terminals.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY 40292.
authors.forename: J W
authors.initials: JW
authors.lastname: Brock
authors.forename: I G
authors.initials: IG
authors.lastname: Joshua
authors.forename: F N
authors.initials: FN
authors.lastname: Miller
authors.forename: F
authors.initials: F
authors.lastname: Li
mesh_terms: D000818:Animals; D001160:Arterioles / Q000187:drug effects; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D009129:Muscle Tonus / Q000187:drug effects; D009132:Muscles / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D004744:Enkephalin, Methionine