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Aquaporins (AQPs) are water channels found widely in bacteria, plants, animals, and humans. There are presently 13 known types of aquaporins in humans (AQP0 to AQP12), which are expressed in various organs. 1) In the kidney, several members of the AQP family are expressed, which are responsible for regulating water volume in the body. Especially in the renal collecting duct, AQP2, which is expressed on the luminal membranes of principal cells, and AQP3 and AQP4, which are expressed on the basolateral membranes of principal cells, are involved in urine concentration by inducing the re-absorption of water from the luminal side to the basolateral side.2) The capacity for water re-absorption in the renal collecting duct is thought to determine urine volume. Because either protein mutations or a decreased expression of AQP2 is found in patients with nephrogenic diabetes insipidus who present with marked polyuria, AQP2 is considered to play the most important role in water re-absorption in the renal collecting duct. 3,4) Enhanced expression of renal AQP2 has been reported when polyuria occurs in streptozotocin (STZ)-induced type I diabetes model mice. 5,6) In addition, we previously found that the level of renal AQP2 expression increases along with the pathological progression of type II diabetes mellitus using KKAy mice, the animal model of type II diabetes. 7) Although this increased AQP2 expression in the kidneys has been regarded as a possible compensatory mechanism to alleviate dehydration in polyuria, the physiological significance of the increase in renal AQP2 expression in diabetes remains unknown. Recently, a method to generate a mouse model of nephrogenic diabetes insipidus by administering lithium carbonate (Li 2 CO 3 ) was reported. 8,9) Almost all of the Li 2 CO 3 absorbed into the body is eliminated unchanged via glomerular filtration. Lithium is incorporated into principal cells of the collecting tubules via epithelial sodium channels that are dominantly expressed on the collecting tubules.10) The incorporated lithium decreases cAMP by suppressing the activity of adenylate cyclase (AC), resulting in the inhibition of pathways for both AQP2 and AQP3 transcription and membrane transfer. 8,9,11) Using Li 2 CO 3 , we constructed an experimental system to decrease only the expression levels of AQPs, with no change in urinary osmotic pressure, to investigate the relationship between urine volume and the expression levels of AQPs. In this study, we developed this experimental system by administering Li 2 CO 3 to STZ-induced type I diabetes model mice. MATERIALS AND METHODSMaterials 2-Mercaptoethanol, bromophenol blue, Folin and Ciocalteu's phenol reagent, polyoxyethylene (20) sorbitan monolaurate (Tween 20), sodium dodecyl sulphate (SDS), and 2-amino-2-hydroxymethyl-1,3-propanediol (Tris) were purchased from Wako Pure Chemical Industries, Ltd. (Tokyo, Japan). Anti-rat aquaporin 1, anti-rat aquaporin 2, anti-rat aquaporin 3, and anti-rat aquaporin 4 antibodies were purchased from Alomone Labs, Ltd. (Jerusalem, ...

The purpose of the present study was to determine the factors of falls among community dwelling elderly. As subjects, 172 (31 males and 141 females, aged 60 to 95) elderly adults in Kasari town of Amami island participated in the study which evaluated 20 items. Incidence of falls were 17%, and incidence of elderly adults who had suffered fractures in falls was 33.3%. The places of falls were the living room and the road. The results indicate that falls was related to factors "Cannot lift a bucketful of water" and "Poor physical condition".