These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Studies on the mechanism of 5-HT1 receptor-induced smooth muscle contraction in dog saphenous vein.
    Author: Sumner MJ, Feniuk W, McCormick JD, Humphrey PP.
    Journal: Br J Pharmacol; 1992 Mar; 105(3):603-8. PubMed ID: 1320980.
    Abstract:
    1. We have investigated the mechanism of smooth muscle contraction evoked by activation of 5-HT1-like receptors in dog isolated saphenous vein. 2. In the presence of the 5-HT2 receptor antagonist, ritanserin (0.1 microM), concentration-effect curves (10 nM-300 microM) for 5-hydroxytryptamine (5-HT)-induced smooth muscle contraction were biphasic. This could be attributed to a direct action on 5-HT1-like receptors at low concentrations of 5-HT (10 nM-10 microM) and an indirect (through the release of noradrenaline from sympathetic neurones) activation of postjunctional alpha-adrenoceptors at higher 5-HT concentrations. In contrast, concentration-effect curves (100 nM-100 microM) for sumatriptan-induced contractions were not biphasic, and were due solely to activation of 5-HT1-like receptors. 3. Smooth muscle contractions evoked either by low concentrations of 5-HT or by sumatriptan were abolished by removal of extracellular calcium and were markedly inhibited, but not abolished, by the calcium channel blocker, verapamil (1-30 microM). In contrast, contractions evoked by high concentrations of 5-HT were markedly less sensitive to removal of extracellular calcium or to verapamil. 4. 5-HT and sumatriptan also inhibited (to a maximum of about 50%) prostaglandin E2 (PGE2, 5 microM)-stimulated adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation. This effect was mimicked by the alpha 2-adrenoceptor agonist, azepexole (B-HT933) but not by the alpha 1-adrenoceptor agonist, methoxamine.5. In contrast to mediation of smooth muscle contraction, the 5-HT1-like receptor-mediated inhibition of PGE2-stimulated cyclic AMP formation evoked by 5-HT or sumatriptan was not attenuated by removal of extracellular calcium or by verapamil (1 microM).6. A directly-acting inhibitor of adenylyl cyclase, 2',3'-dideoxyadenosine (1 mM) inhibited PGE2-stimulated cyclic AMP formation but did not produce smooth muscle contraction.7. These results suggest that contractile responses of dog isolated saphenous vein arising through activation of 5-HT1-like receptors are associated with both an influx of extracellular calcium ions (to a large extent via voltage-dependent channels) and an inhibition of adenylyl cyclase. However, although these two responses are coupled to the same receptor, they appear to be independent.
    [Abstract] [Full Text] [Related] [New Search]