title: 5-Hydroxytryptamine-induced NO-dependent relaxation in isolated strips of monkey popliteal lymph nodes.
abstract: 5-Hydroxytryptamine (5-HT, 0.01-100 microM) and 5-carboxamidotryptamine (5-CT, 0.001-10 microM) produced dose-related relaxations in strips cut from monkey popliteal lymph nodes precontracted with a perfusion of Krebs bicarbonate solution containing 80 mM KCl. These 5-HT agonists caused no significant effect on the basal tone of the lymph node strips. The 5-HT-induced relaxation is competitively antagonized by pretreatment with a selective 5-HT1-like receptor antagonist, methiothepin (0.01-0.1 microM). Schild plot analysis showed that the pA2 value and slope of methiothepin against 5-HT were 8.80 +/- 0.11 and 0.99 +/- 0.07 (n = 6), respectively. Pretreatment with methysergide (0.01-0.1 microM) significantly attenuated the 5-HT-induced relaxation of the strips. On the other hand, treatment with ketanserin (0.01-0.1 microM) and ICS-205-930 (0.01-0.1 microM) caused no significant effect on the 5-HT-or the 5-CT-induced relaxation. The 5-HT-induced relaxation was significantly reduced by 10 microM NG-monomethyl-L-arginine, which was reversed by 1 mM L-arginine. The relaxation in the lymph node strips was also significantly reduced by treatment with 10 microM methylene blue but not with 30 microM aspirin. These results suggest that 5-HT1-like receptors exist in the monkey popliteal lymph nodes. Stimulation of these receptors produces an endogenous nitric oxide (NO)-dependent relaxation in lymph node smooth muscle through an activation of cytosolic guanylate cyclase in the cells.
authors.affiliation: First Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Mizuno
authors.forename: T
authors.initials: T
authors.lastname: Ohhashi
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008198:Lymph Nodes / Q000187:drug effects / Q000502:physiology*; D008251:Macaca; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D019323:omega-N-Methylarginine
chemical_list: D017366:Serotonin Receptor Agonists; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D012701:Serotonin; D008719:Methiothepin; C047087:5-carboxamidotryptamine; D001120:Arginine; D007650:Ketanserin; D001241:Aspirin; D008751:Methylene Blue