Binding sites of atrial natriuretic peptide (ANP) in the mammalian cochlea and stimulation of cyclic GMP synthesis.
The distribution of binding sites for atrial natriuretic peptide (ANP) has been examined in frozen sections of the guinea pig inner ear by means of autoradiography. The highest density was found in the stria vascularis of all cochlear turns. In membrane preparations of stria vascularis in vitro, the production of the second messenger cGMP was strongly stimulated by synthetic ANP in a dose dependent manner. Adenylate cyclase was neither stimulated nor inhibited by ANP, thus suggesting, that the binding sites coincide with an ANP receptor, which is coupled to guanylate cyclase but not negatively coupled to an adenylate cyclase molecule. The production of cyclic GMP could not be reduced by GDP-beta S, a strong inhibitor of the Gs protein. We conclude the existence of an ANP receptor-guanylate cyclase signal transfer system, similar to the beta 2 receptor-adenylate cyclase system in the inner ear, without coupling to a G protein. ANP might play a role in sodium and water regulation of the endolymph and might antagonize the action of vasopressin.
Koch
T
T
Department of Otorhinolaryngology, Medizinische Hochschule, University of Hannover, FRG.
Gloddek
B
B
Gutzke
S
S
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001345:Autoradiography; D001665:Binding Sites; D003051:Cochlea / Q000737:chemistry* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000096:biosynthesis*; D005629:Frozen Sections; D019204:GTP-Binding Proteins / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006168:Guinea Pigs; D011863:Radioimmunoassay; D013316:Stria Vascularis / Q000737:chemistry*; D013873:Thionucleotides / Q000494:pharmacology
D013873:Thionucleotides; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D009320:Atrial Natriuretic Factor; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D006152:Cyclic GMP