title: Chronic hyperosmolality enhances ANP-dependent cGMP production via stimulation of transcription and protein synthesis in cultured rat IMCD cells.
abstract: Recently, we found that hyperosmolality acutely inhibited atrial natriuretic peptide (ANP) dependent cGMP production by reducing ANP binding sites in cultured rat inner medullary collecting duct (IMCD) cells. Therefore, the present study was undertaken to evaluate the chronic effect of hyperosmolality on ANP dependent cGMPproduction in IMCD cells. Cell culture was carried out either in an iso-osmotic or hyperosmotic solution consisting of equi-isomolar NaCl and/or urea. Incubations with ANP and/or other agents were performed under the same osmotic conditions. ANP or SNP stimulated cGMP production was enhanced in a chronically hyperosmotic medium. These changes occurred in an osmolality-dependent manner. Hyperosmolality with sodium alone or with sodium and urea, but not with urea alone, was effective for the enhancement of ANP action. There was no significant difference between 125I-ANP specific bindings under iso-osmotic and hyperosmotic conditions. Incubation with cytoskeleton modulators did not affect ANP-dependent cGMP production stimulated by hyperosmolality. On the other hand, both actinomycin D, an inhibitor of transcription, and cycloheximide, an inhibitor of protein synthesis, prevented the stimulatory effects of hyperosmolality. The results suggest that chronic hyperosmolality enhances ANP-dependent cGMP production via stimulation of transcription and protein synthesis in cultured rat IMCD cells.
authors.affiliation: Department of Nephrology, Jichi Medical School, Minamikawachi, Tochigi, Japan. eishun@jichi.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Kusano
authors.forename: Osamu
authors.initials: O
authors.lastname: Iimura
authors.forename: Fujimaro
authors.initials: F
authors.lastname: Ishida
authors.forename: Tetsu
authors.initials: T
authors.lastname: Akimoto
authors.forename: Morimasa
authors.initials: M
authors.lastname: Amemiya
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ando
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Asano
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000502:physiology*; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D006152:Cyclic GMP / Q000096:biosynthesis*; D003513:Cycloheximide / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D011500:Protein Synthesis Inhibitors; D011955:Receptors, Drug; D003609:Dactinomycin; D003571:Cytochalasin B; D012965:Sodium Chloride; D009320:Atrial Natriuretic Factor; D003513:Cycloheximide; D006152:Cyclic GMP; D003078:Colchicine