The slow cyclic GMP increase caused by serotonin in NG108-15 cells is not inhibited by antagonists of known serotonin receptors: possible existence of a new receptor subtype coupled with membrane-bound guanylate cyclase.
Characterization of the serotonin (5-HT)-induced cyclic GMP (cGMP) elevation was investigated in comparison with bradykinin- and ANP-induced elevations in NG108-15 cells. At 20 s, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM, 100 microM), a membrane-permeabilized Ca2+ chelator, or N-monomethyl-L-arginine (NMMA, 300 microM), an inhibitor of L-arginine-derived nitric oxide (NO) synthesis, inhibited 5-HT-induced elevation by approximately 40%, and completely inhibited bradykinin-induced response. Neither 5-HT- nor ANP-induced cGMP elevation at 10 min was affected by BAPTA-AM or NMMA. The cGMP elevated by 5-HT as well as by ANP was effluxed to the extracellular medium. These results and our previous report suggest that 5-HT stimulates two subtypes of 5-HT receptors in NG108-15: first, 5-HT3 subtype stimulating Ca(2+)-sensitive cytosolic guanylate cyclase through NO derived from L-arginine and second, a probably novel 5-HT receptor subtype involved in activation of membrane-bound guanylate cyclase.
Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
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Tohda
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Sakuma
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Y
Nomura
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology / Q000031:analogs & derivatives; D005910:Glioma; D006162:Guanylate Cyclase / Q000378:metabolism*; D006822:Hybrid Cells / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D009447:Neuroblastoma; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*
D002614:Chelating Agents; D011985:Receptors, Serotonin; D012701:Serotonin; D004533:Egtazic Acid; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D006152:Cyclic GMP; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D001920:Bradykinin