| Original Article : Altered Regulation of Water Channels and Sodium Transporters in Fasting-induced Polyuria in Rat Kidney |
| Byoung Seok Park, M.D.1, Eun Hui Bae, M.D.1, Woo Heon Kang, M.D.3 Jeong Woo Park, M.D.1, Seong Kwon Ma, M.D.1, Nam Ho Kim, M.D.1, Ki Chul Choi, M.D.1, JongUn Lee, M.D.2 and Soo Wan Kim, M.D.1 |
Departments of Internal Medicine1 and Physiology2
Chonnam National University Medical School, Gwangju, Korea Department of Medicine3
College of Medicine, Cheju National University, Jeju, Korea |
| 기초연구 : 금식유발 다뇨 및 요농축력 감소 병인으로 신장 수분통로 및 나트륨 운반체 조절 변화 |
| 박병석1 |
| 전남대학교 의과대학 내과학교실1, 생리학교실2, 제주대학교 의과대학 내과학교실3 |
|
|
| Abstract |
Purpose
Starvation causes impairment in the urinary concentration ability. However, the molecular basis for the impaired urinary concentration and polyuria remains undefined. We examined the effects of food deprivation on the water handling by the kidney and it's regulatory mechanism.
Methods
Sprague-Dawley rats were used. They were placed in metabolic cages and deprived of food but had free access to water for 24 hours. Control rats had free access to both water and food.
Protein expression of aquaporin-2 (AQP2) and Na+-K+-2Cl－ cotransporter (NKCC2) was determined in the kidney by Western blot analysis. Protein expression of type VI adenylyl cyclase and prostaglandin E2 synthase (PGES) was determined. Urinary PGE2 excretion was also determined by radioimmunoassay.
Results
Food deprivation (FD) resulted in impaired urinary concentration associated with decreased tubular water reabsorption and increased urine output. The expression of AQP2 proteins was significantly decreased in the inner stripe of the outer medulla (ISOM). The expression of NKCC2 was not affected in ISOM. The adenylyl cyclase VI expression was increased in ISOM in FD rats.
The protein expression of PGES was decreased in the cortex/OSOM and ISOM. The 24 hr urinary excretion of PGE2 was significantly decreased in FD rats compared with controls.
Conclusion
These findings indicate that FD-induced urinary concentration defect may related to a reduced abundance of AQP2 in the kidney. It is also suggested that the primary impairment in the pathway to the activation of AQP2 in food deprivation is independent of vasopressin/cAMP or prostaglandin activity.
Key words : Food deprivation, Polyuria, Aquaporin, Adenylyl cyclase, Prostaglandin |
| Key Words:
Food deprivation, Polyuria, Aquaporin, Adenylyl cyclase, Prostaglandin |
|
PDF Links
Download Citation
