title: Participation of mast cell 5-hydroxytryptamine in the vasoconstrictor effect of neurotensin in the rat perfused hindquarter.
abstract: Neurotensin (NT) (1 X 10(-8) - 1.5 X 10(-6) g ml-1) caused a transient, dose-dependent increase in perfusion pressure in the rat perfused hindquarter. The vasoconstrictor effect of NT was associated with a short-lived, dose-dependent release of histamine and 5-hydroxytryptamine (5-HT) in the hindquarter effluent. Compound 48/80, a classical mast cell secretagogue, also elicited a vasoconstrictor effect in, and release of histamine from, the rat hindquarter. The vasoconstrictor effect and the release of histamine and 5-HT evoked by NT were much smaller in hindquarters derived from rats pretreated with compound 48/80 for 4 days to cause mast cell depletion than in hindquarters derived from control rats. The mast cell inhibitor cromoglycate (4 mg ml-1) inhibited by about 50% the histamine releasing effect and vasoconstriction produced by the lowest concentrations of NT utilized. The histamine releasing effect of compound 48/80 was more sensitive to blockade by cromoglycate than that of NT. The steroidal antiinflammatory and antiallergic drug dexamethasone did not affect the histamine and 5-HT releasing effect of NT. The vasoconstrictor effects of NT, compound 48/80 and 5-HT were markedly reduced by the 5-HT receptor antagonist methysergide (1 X 10(-7) g ml-1). Histamine (1 X 10(-6) - 10(-4) g ml-1) evoked a decrease in perfusion pressure in hindquarters pre-exposed to noradrenaline. The results suggest the participation of mast cell 5-HT in the vasoconstrictor effect of NT in the rat perfused hindquarter.
mesh_terms: D000818:Animals; D004205:Cromolyn Sodium / Q000494:pharmacology; D006614:Hindlimb; D006632:Histamine / Q000097:blood / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D008784:Methysergide / Q000494:pharmacology; D009496:Neurotensin / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D012701:Serotonin; D009496:Neurotensin; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; D004205:Cromolyn Sodium; D009638:Norepinephrine; D008784:Methysergide