Effect of hyperosmolality on production and mRNA expression of ET-1 in inner medullary collecting duct.
The effects of hyperosmolality on the production and mRNA expression of endothelin-1 (ET-1) in inner medullary collecting duct (IMCD) were examined in the present study. Osmolality in incubation media was changed from 290 to 490 or 690 mosmol/kgH2O by adding NaCl, urea, mannitol, or raffinose. A preliminary experiment was carried out using tubule suspension from the inner medulla. Hyperosmolality by NaCl stimulated ET-1 accumulation in rats (from 323.5 +/- 76.3 to 478.0 +/- 108.4 and 573.7 +/- 47.8 pg.mg protein-1 x 24 h-1 in 290, 490, and 690 mosmol/kgH2O, respectively) and rabbits. In contrast, hyperosmolality by urea markedly decreased ET-1 accumulation and hyperosmolality by mannitol showed no effect on it. We next examined whether hyperosmolality changes ET-1 mRNA. After incubation in isotonic or hypertonic solution for 6 h, ET-1 mRNA was determined using reverse transcription and polymerase chain reaction (PCR) in microdissected IMCD and glomerulus. Hyperosmolality by NaCl and raffinose significantly increased the PCR products of ET-1 mRNA in IMCD, whereas mannitol did not. The stimulatory effect of hyperosmolality by NaCl on ET-1 mRNA expression was not observed in glomerulus. Our data suggested a stimulatory effect of hyperosmolality on production and mRNA expression of ET-1 in IMCD but not in glomerulus.
Yang
T
T
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Terada
Y
Y
Nonoguchi
H
H
Ujiie
K
K
Tomita
K
K
Marumo
F
F
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D001483:Base Sequence; D003470:Culture Media / Q000494:pharmacology; D004247:DNA / Q000235:genetics; D016232:Endothelins / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression / Q000235:genetics*; D006982:Hypertonic Solutions / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D007685:Kidney Tubules, Collecting / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D011817:Rabbits; D011863:Radioimmunoassay; D012965:Sodium Chloride / Q000494:pharmacology; D014158:Transcription, Genetic; D014508:Urea / Q000494:pharmacology
D003470:Culture Media; D016232:Endothelins; D006982:Hypertonic Solutions; D012333:RNA, Messenger; D001127:Arginine Vasopressin; D008353:Mannitol; D012965:Sodium Chloride; D014508:Urea; D004247:DNA