5-HT7 receptor-mediated relaxation of the oviduct in nonpregnant proestrus pigs

摘要: The effects of 5-hydroxytryptamine (5-HT) on the muscle tonus ampulla and isthmus oviduct isolated from nonpregnant proestrus pigs were investigated, 5-HT receptor subtype mechanisms responses analyzed. (1 nM–10 μM) caused a relaxation longitudinal circular muscles in concentration-dependent manner. Tetrodotoxin did not change relaxation, indicating direct action smooth cells. EC50 value was significantly lower than that but maximum relaxations similar. also both layers smaller isthmus. 5-Carboxamidotryptamine (5-CT), 5-methoxytryptamine (5-MeOT) (±)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) mimicked isthmic by 5-HT, ranking order 5-CT>5-HT>5-MeOT>8-OH-DPAT. On other hand, oxymethazoline, 2-methyl-5-hydroxytryptamine (2-methyl-5-HT), α-methyl-5-hydroxytryptamine (α-methyl-5-HT), [endo-N-8-methyl-8-azabicyclo-(3,2,1) oct-3-yl]-2,3-dihydro-3-ethyl-2-oxo-1H-benzimidazol-1-carboxamide (BIMU-1), ergotamine dihydroergotamine less effective. decreased ketanserin, 2-methoxy-4-amino-5-chlorobenzoic acid 2-(diethylamino)ethyl ester (tropisetron) or [1[2-(methylsulphonyl) amino ethyl]-4-piperidinyl]methyl-1-methyl-1H-indole-3-carboxylate (GR113808) antagonized following compounds competitive manner (with pKb values parentheses): 2a-[4-(4-phenyl-1,2,3,6-tetrahydropyridyl)butyl]-2a,3,4,5-tetrahydro-benzo[cd]indol-2(1H)-one (DR4004, 9.31), methiothepin (8.91), methysergide (7.95), metergoline (7.98), mianserin (7.69), mesulergine (8.4), spiperone (6.86) clozapine (7.4). correlation these with pKi cloned 5-HT7 pA2 porcine uterus high significant. 4-(3-Butoxy-4-methoxybenzyl)-imidazolidin-2-one (Ro20-1724) enhanced zaprinast, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) l-nitroarginine methylester (l-NAME) to 5-HT. increased cyclic AMP oviduct. Ampulla contained single class [3H]5-CT binding sites similar Kd (0.4 nM), density receptors 2.4 times higher ampulla. A significant found between those receptors. Isoprenaline, sodium nitroprusside, vasoactive intestinal peptide pituitary adenylate cyclase activating effective causing In conclusion, receptor, functionally correlated type, mediates through an increase intracellular AMP. degrees 5-HT-induced different due heterogeneous distribution strongest activation suggests plays important physiological role regulation contractility.