OBJECTIVEMany studies have shown that tissue development is closely correlated with fluid transport. Aquaporins (AQPs) are a group of cell membrane proteins that actively and selectively transport water. This study aimed to investigate the changes of AQPs expression during lung development in rats in order to elucidate the role of AQPs in the rat lung development.

METHODSAQP1, AQP3, AQP4 and AQP5 proteins and mRNA in the lung cell membrane were measured by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) respectively in the 20-day-old embryo (E20), 7-day-old newborn rat, and one-month-old young and adult rats. The correlation between AQPs expression and lung development was studied.

RESULTSWith increasing age, the lung development showed a dynamic and successive course, with the most rapid from the fetus to the newborn rat, and then a slowed down afterwards. AQPs mRNA was weakly expressed in the lung of the E20 group. Lung AQPs mRNA and protein increased rapidly after birth until adulthood. The AQPs distribution patterns in the lung were unique with no duplication. There was a positive correlation between AQPs expression and lung development (P<0.05).

CONCLUSIONSIn addition to being involved in the transepithelial transport of water in the lung, AQPs is also related to its development.

Animals ; Aquaporins ; analysis ; genetics ; physiology ; Immunohistochemistry ; Lung ; embryology ; metabolism ; RNA, Messenger ; analysis ; Rats ; Rats, Wistar

BACKGROUNDThe relationship between melanosis coli (MC) and aquaporin 8 (AQP8) has not yet been elucidated. The aim of this research was to investigate the relationship between the expression of AQP8 and the pathological mechanism of MC.

METHODSExpression of AQP8 was detected by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) in 37 MC colon tissues and 13 control colon tissues. Global gene expression analysis was also used to identify differently expressed genes. Its relationship with MC was analyzed by SPSS 11.5 statistical software.

RESULTSThe positive rate of AQP8 expression detected by immunohistochemistry in the MC group was 24.3% (9/37), significantly lower than the 69.2% (9/13) in the control group (P < 0.05). The relative expression level of AQP8 in MC group was 0.639 ± 0.160, lower than 0.921 ± 0.148 of controls (P < 0.05). Global gene expression analysis showed that AQP8 mRNA expression was downregulated in MC patients.

CONCLUSIONSThe decreased AQP8 expression in MC patients indicates that chronic use of laxatives containing anthraquinone may cause reduced water absorption. The expression of AQP8 may be related to MC.

Adult ; Aged ; Aquaporins ; analysis ; genetics ; Colonic Diseases ; etiology ; Female ; Gene Expression ; Humans ; Immunohistochemistry ; Male ; Melanosis ; etiology ; Middle Aged

OBJECTIVETo investigate the expression of aquaporin-1 (AQP1) in the human peritoneum and to evaluate the effect of peritoneal dialysis (PD) on its expression.

METHODSPeritoneal biopsies were obtained from normal subjects (n = 10), uremic nondialysis patients (n = 12) at catheter insertion and PD patients (n = 10) at the time of catheter removal, reinsertion or renal transplantation. Western blot, immuno-histochemical staining and reverse transcript-polymerase chain reaction (RT-PCR) techniques were used to investigate AQP1 expression.

RESULTSAll peritoneal samples expressed AQP1 at both mRNA and protein levels. Western blot revealed a major band at 28 kD as well as more diffuse bands between 35 and 50 kD. The 28 kD band represents the nonglycosylated form of the protein while the 35 - 50 kD bands correspond to glycosylated AQP1. Immunohistochemical staining found the positive deposits were distributed in the mesothelial cells, endothelial cells of capillaries, venules and small veins, whereas no signal was detected in the arterioles. Semi-quantitative analysis showed that AQP1 expression was remarkably stable in all samples, whatever their origin (P > 0.05).

CONCLUSIONSOur findings suggested that AQP1 is the molecular counterpart of an ultra small pore during PD. Secondly, the peritoneal mesothelial cell might also be involved in peritoneal transcellular water transport. As regards whether or not the structural or distributional alterations of AQP1 in the peritoneum may be more obviously expressed during PD, further study is needed.

Adult ; Aquaporin 1 ; Aquaporins ; analysis ; Blood Group Antigens ; Female ; Humans ; Male ; Middle Aged ; Peritoneal Dialysis ; Peritoneum ; chemistry ; physiology ; Uremia ; physiopathology

The present study was aimed at examining the regulation of aquaporin (AQP)-2 water channels in the kidney in two-kidney, one clip (2K1C) hypertension. Rats were made 2K1C hypertensive for 6 weeks, and their expression of AQP2 channel proteins was determined in the clipped and contralateral kidneys. To examine the upstream affecting AQP2 channels, adenylyl cyclase activity was also determined. Along with the hypertension, in the clipped kidney, the abundance of AQP2 proteins was significantly decreased in the cortex, outer and inner medulla, while their trafficking remained unaltered. Concomitantly with the reversal of the blood pressure at 24 hours following removal of the clip, the AQP2 abundance also returned to the control level. The arginine vasopressin-evoked generation of cAMP was decreased in the clipped kidney, which again was reversed to the control level following removal of the clip. In contrast, the expression of AQP2 channels as well as the activity of adenylyl cyclase remained unaltered in the contralateral kidney. These results indicate an altered regulation of AQP2 water channels in the clipped kidney in 2K1C hypertension.
Adenylate Cyclase/metabolism ; Animal ; Aquaporins/*analysis ; Blood Pressure ; Cyclic AMP/biosynthesis ; Hypertension, Renovascular/*metabolism ; Kidney/*chemistry ; Male ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: Several water channels (aquapoins; AQP) that belong to the MIP (major intrinsic protein) family have identified. In the selected tissues including red blood cells or renal tubules, water movements are abundant and/or physiologically important. Unexpectedly, a high water permeability of human and ram sperm has been reported. Recent studies showed that AQP7 and AQP8 are present in testes so that the high water permeability of human sperm suggested to be mediated by AQPs. METHOD: To identify the identity of aquaporins expressed in testes, RT-PCR was performed using degenerative primers, which were designed to correspond to highly conserved sequences surrounding the Asn-Pro-Ala (NPA) motifs in the aquaporins. New expressed AQP series were reconfirmed by immunohistochemical study using rabbit polyclonal antibodies. RESULTS: DNA sequencing of PCR products revealed that AQP2 and AQP3 mRNA as well as AQP7 and AQP8 are expressed in human and rat testes, AQP2 are expressed in spermatozoa, interstitial cells and myofibroblasts and AQP3 are expressed in myofibroblasts of semineferous tubules on immunocytochemical stain. CONCLUSION: These results indicate that multiple aquaporins are expressed in testes, and that they may have important roles in the spermatogenesis and the germ cell function of testis.
Animals ; Antibodies ; Aquaporins* ; Conserved Sequence ; Erythrocytes ; Germ Cells ; Humans* ; Myofibroblasts ; Permeability ; Polymerase Chain Reaction ; Rats* ; RNA, Messenger ; Sequence Analysis, DNA ; Spermatogenesis ; Spermatozoa ; Testis* ; Water Movements

OBJECTIVETo study the relationship of renal aquaporin -1, -2, -3, and -4 (AQP1-4) expression with renal parenchymal thickness and glomerular filtration rate (GFR) in children with congenital hydronephrotis.

METHODSRenal tissue samples were obtained from 10 kidneys of 10 children (age: 62.3±18.3 months) with hydronephrosis and who underwent Anderson-Hynes pyeloplasty. Renal control samples were obtained from 6 children (age: 62.7±17.1 months) undergoing nephrectomy for nephroblastoma and were confirmed histologically as normal renal tissues. Renal parenchymal thickness of the hydronephrotic kidneys was measured by ultrasound preoperatively and was verified at operation. Renal GFR was assessed using 99mTc-DTPA scintigraphy preoperatively. Western blot was used to examine the expression of AQP1-4 in the renal tissues. The correlations of renal AQP1-4 expression with the renal parenchymal thickness and GFR were assessed by Pearson correlation analysis.

RESULTSThe expression of AQP1-4 in the hydronephrotis group was markedly reduced compared to that in the control group (P<0.05). The mean renal parenchymal thickness of the hydronephrotic kidney was 4.59±2.25 mm measured by ultrasound preoperatively. The mean GFR of the obstructed kidney was significantly lower than that of the contralateral kidney in the hydronephrosis group (40±12 mL/min vs 105±20 mL/min; P<0.05). The expression of AQP1, 2, 3 and 4 was positively correlated with preoperative renal GFR and renal parenchymal thickness in the hydronephrosis group (P<0.05). Renal parenchymal thickness was positively correlated with renal GFR (P<0.05).

CONCLUSIONSThe expression of renal AQP1-4 is reduced in children with congenital hydronephrosis. The expression levels of AQP1-4 are positively correlated with renal parenchymal thickness and GFR.

Aquaporins ; analysis ; Child ; Child, Preschool ; Female ; Glomerular Filtration Rate ; Humans ; Hydronephrosis ; congenital ; metabolism ; pathology ; Kidney ; pathology ; Male ; Sulfhydryl Compounds ; Technetium Tc 99m Aggregated Albumin ; Technetium Tc 99m Pentetate

OBJECTIVETo map the disease locus for a congenital cataract family, and detect the disease-causing gene.

METHODSAn autosomal dominant congenital cataract family was genotyped by genome wide scan using 382 autosomal microsatellite markers from ABI-MD10. Two-point linkage analysis was carried out by the MLINK program.

RESULTSThe disease locus of this family was mapped at 12p11.2-q15. Sequence analysis of a candidate gene-major intrinsic protein (MIP) revealed a novel missense mutation G-->A at the nucleotide 702 in exon 4, which resulted in a substitution of arginine to lysine at codon 233 (p.R233K).

CONCLUSIONThe mutation G-->A at nt702 in MIP gene was associated with the binocular polymorphic congenital cataract in the family. This transition occurring at the C-terminus of MIP might decrease the stability of the C-end of the protein and impact the function of the protein.

Aquaporins ; genetics ; Base Sequence ; Cataract ; genetics ; Exons ; genetics ; Eye Proteins ; genetics ; Female ; Genome, Human ; genetics ; Genomics ; Genotype ; Humans ; Male ; Mutation, Missense ; Pedigree ; Polymorphism, Genetic ; Sequence Analysis, DNA

OBJECTIVETo investigate the rule of the aquaporin-4 (AQP4) expression in acute ischemic brain edema, and to study the correlation between AQP4 expression and diffusion-weighted imaging (DWI).

METHODSThirty-six Wistar rats were divided into 2 groups randomly, control group (n = 12) and operation group (n = 24) in which right middle cerebral artery of each animal had been occluded unilaterally (MCAO) at interval times of: 15 minutes, 30 minutes, 1 hours, 3 hours, 6 hours and 24 hours, respectively. The operation process of the control group was the same as the operation group except for the MCAO. All groups were examined using DWI. The apparent diffusion coefficient (ADC), relative density (rd) and relative area (rs) of the biggest hyperintensity signal layer on DWI were measured. After that the animals were sacrificed and perfused with the mixture solution consisting of TTC. The biggest layers of the ischemic cerebral tissues in each rat corresponding to the DWI were stained with TTC and examined with immunochemistry (DeltaS), in situ hybridization (alpha) and histology.

RESULTSThere was no significant change in the control group. In the operation group, a hyperintensity signal was found in the DWI of the right MAC territory at 15 minutes after MCAO. The ADC value decreased quickly within one hour after MCAO, while the AQP4 expression, rd-DWI and rs-DWI increased rapidly during this stage. As time progressed, the ADC value decreased further to (2.1 +/- 0.6) x 10(-4) mm(2)/s at 3 hours, and then began to increase slowly till 24 hours. But the AQP4 expression (DeltaS and alpha) and rd as well as the rs continuously increased slowly between 1 hour and 6 hours after MCAO, followed a peak after 6 hours. The AQP4 expression (alpha) showed a positive relationship with the rs-DWI, they all presented two peaks and a plateau. The corresponding sequential pathologic changes were a gradual increase of intracellular edema (within one hour), then an emergence of vasogenic edema (1-6 hours), and final necrosis and liquefaction (6 - 24 hours).

CONCLUSIONSUpregulated expression of AQP4 may play a significant role in acute ischemic brain edema, especially during the stages of intracellular edema and necrosis, but it has no correlation to vasogenic edema. Certainly, the high expression of AQP4 is perhaps one of the most important reasons of the decrease of ADC and hyperintensity on the DWI in the intracellular edema.

Acute Disease ; Animals ; Aquaporin 4 ; Aquaporins ; analysis ; Brain Edema ; etiology ; pathology ; Brain Ischemia ; complications ; pathology ; Diffusion Magnetic Resonance Imaging ; Random Allocation ; Rats ; Rats, Wistar

BACKGROUNDWe analysed and compared the aquaporin 8 (AQP8) expression in ascending and descending colon mucosa between patients with diarrhoea-predominant irritable bowel syndrome (D-IBS) and healthy volunteers, in order to study the relationship between the clinical feature of IBS, the expression of AQP8 and the pathological mechanism of D-IBS.

METHODSSpecimens were taken from the proximal ascending colon or distal descending colon of D-IBS patients (n = 26) and healthy volunteers (n = 30), and AQP8 mRNA expression of each specimen was determined by fluorescent quantitative reverse transcription polymerase chain reaction (FQ-RT-PCR). In patients with D-IBS, the relationship was analysed between AQP8 expression in both ascending and descending colons and clinical features including gender, age of onset, duration of illness, frequency of defecation, and stool characteristics.

RESULTSAlthough AQP8 was present in the epithelium of the ascending and descending colons in healthy persons and D-IBS patients, the AQP8 level of the D-IBS patients was significantly lower than that of the healthy persons (P < 0.01 in the ascending colon, P < 0.05 in the descending colon). AQP8 expression was not correlated with the age of patients with D-IBS (P > 0.05 both in the ascending and descending colons) or the age at the onset (P > 0.05 both in the ascending and descending colons), but closely with the duration of illness (P < 0.05 in the ascending colon, P < 0.01 in the descending colon), frequency of defecation (P < 0.01 in the ascending colon, P < 0.05 in the descending colon) and stool characteristics (P < 0.01 in the ascending colon, P > 0.05 in the descending colon).

CONCLUSIONSThe decreased AQP8 expression in D-IBS patients indicates that dysfunction of colonic absorption may cause reduced water absorption, loose stool and diarrhoea. The expression of AQP8 may be related to D-IBS.

Adult ; Aged ; Aquaporins ; genetics ; Colon ; metabolism ; Diarrhea ; metabolism ; Female ; Humans ; Intestinal Mucosa ; metabolism ; Irritable Bowel Syndrome ; metabolism ; Male ; Middle Aged ; RNA, Messenger ; analysis

OBJECTIVETo determine if aquaporin1 (AQP1) and aquaporin5 (AQP5) are expressed in the alveolar capillary membrane in rats. Moreover, to investigate the alteration of AQP1 and AQP5 in acute injured lungs.

METHODSThe distribution of AQP1 and AQP5 in alveolar capillary membrane were investigated by immunohistochemistry and immunoelectron microscopy with affinity-purified antibodies to human AQP1 and AQP5. To study the possibility that alveolar capillary membrane AQP1 and AQP5 undergo altered regulation, we established a rat model using alveolar instillation of lipopolysaccharide (LPS).

RESULTSImmunolabelling showed AQP1 was stained primarily in the microvascular endotheli a of normal lungs, while AQP5 was expressed in type I pneumocytes. Immunohisto chemical analysis showed a significant decrease in the expression of AQP1 and AQP5 in injured lungs at 4h-48h after LPS instillation. AQP1 protein was resumed partly at 24h after LPS instillation and steroid administration, whereas AQP5 was unchanged.

CONCLUSIONThe decreased expressions of AQP1 and AQP5 in injured lungs suggest that both of them may play a role in abnormal fluid transportation.

Animals ; Aquaporin 1 ; Aquaporin 5 ; Aquaporins ; analysis ; Immunohistochemistry ; Lipopolysaccharides ; toxicity ; Lung ; metabolism ; Male ; Membrane Proteins ; Microscopy, Immunoelectron ; Rats ; Rats, Sprague-Dawley ; Respiratory Distress Syndrome, Adult ; metabolism ; pathology