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Abstract

Thirteen mammalian aquaporin (AQP) isoforms have been identified, and they have a unique tissue-specific pattern of expression. AQPs have been documented in the reproductive system of both male and female humans, rats, and mice. However, tissue expression and cellular and subcellular localization of AQPs are unknown in the female reproductive system of pigs. In this study, AQP1 immunoreactivity was detected in the capillary endothelium of the ovary. Distinct immunolabeling of capillary endothelium was also observed in the oviduct and uterus. AQP5 was expressed in flattened follicle cells of primordial follicles, granulosa cells of developing ovarian follicles, and muscle cells of the oviduct and uterus. Staining of AQP5 was also observed in the epithelial cells of the oviduct and uterine epithelium. AQP9 immunoreactivity was observed in granulosa cells of developing follicles. AQP9 was also localized in the luminal epithelial cells of the oviduct and uterine epithelia cells. This is, to our knowledge, the first study that shows tissue expression and cellular and subcellular localization of AQPs in the reproductive system of the female pig. Moreover, these results suggest that several subtypes of the AQPs (AQP1, 5, and 9) are involved in regulation of water homeostasis in the reproductive system of gilts.

Keywords

aquaporins immunolocalization female reproductive system pig

Aquaporins (AQPs) are water-selective channels that allow water transport through the plasma membrane of the cells. These proteins were identified more than a decade ago (Preston and Agre 1991). In mammalians cells, at least 13 AQP subtypes (AQP0-AQP12) have been found, and many other AQPs have also been identified in amphibians, plants, yeast, and bacteria (Verkman and Mitra 2000). On the basis of their permeability properties, they have been divided into three groups: (a) aquaporins—selectively permeating water consisting of AQP0, AQP1, AQP2, AQP4, AQP5, AQP6, and AQP8; (b) aquaglyceroporins—permeating water and glycerol consisting of AQP3, AQP7, AQP9, and AQP10; and (c) superaquaporins—having poorly conserved asparagine-proline-alanine (NPA) boxes consisting of AQP11 and AQP12 (reviewed by Ishikawa et al. 2006).

The first confirmation of AQP in the female reproductive system was obtained by isolating and sequencing the cDNA encoding a water channel from the human uterus (Li et al. 1994). Afterward, Li et al. (1997) found AQP1 mRNA in the rat uterus. To date, based on protein expression, at least nine AQP iso-forms have been shown to be expressed in the female reproductive system of humans, rats, and mice (reviewed by Huang et al. 2006). Their specific expression pattern suggests that they play a role in water movement between the intraluminal, interstitial, and capillary compartments. There is also evidence indicating that ovarian steroid can regulate the expression of several AQPs (Jablonski et al. 2003; Branes et al. 2005; Lindsay and Murphy 2006). Nevertheless, data concerning the expression and role of AQPs in female reproductive tissues are still very limited and not available in relation to farm animals.

The aim of this study was therefore to examine the tissue expression and cellular and subcellular localization of AQPs in the reproductive system of gilts.

Materials and Methods

Experimental Animals

All experiments were performed in accordance with the principles and procedures of Animal Ethics Committee of the University of Warmia and Mazury in Olsztyn. Tissue samples were recovered from mature cross-bred gilts on days 17-19 of the estrous cycle (follicular phase). The animals were studied during the third estrous cycle, which was controlled with vasectomized boars, and additionally, the stage of the cycle was confirmed, as previously shown (Akins and Morrissette 1968).

Primary Antibodies

In this study, affinity-purified polyclonal antibodies (SulfoLink Kit; Pierce, Rockford, IL) to the following AQPs were used: AQP1 (Terris et al. 1996), AQP2 (Nielsen et al. 2006), AQP3 (Kim et al. 2005), AQP4 (Vajda et al. 2002), AQP5 (Nielsen et al. 1997), AQP7 (Nejsum et al. 2000), AQP8 (Elkjaer et al. 2001), AQP9 (Carbrey et al. 2003), and AQP11 (Gorelick et al. 2006).

SDS-PAGE and Immunoblotting

After isolation, the tissues were immediately placed in icecold dissection buffer (0.3 M sucrose, 25 mM imidazol, 1 mM EDTA in ddH₂O, pH 7.2) containing 8.4 μM leupeptin and 0.4 mM pefabloc (Skowronski et al. 2007). The tissue samples were homogenized using an ultra Turrax T8 homogenizer (IKA Labortechnik; Staufen, Germany) and centrifuged at 4000 × g for 15 min at 4C. The supernatant diluted in SDS buffer contained a final concentration of 62 mM Tris (hydroxymethyl)-amino-methane, 0.1 M SDS, 8.7% glycerol, 0.09 mM bromophenol blue, and 0.04 M dithiothreitol (DTT), pH 6.8. The protein samples were heated for 5 min at 90C and stored in a refrigerator for further analysis.

The samples were warmed to 37C and were loaded into 12.5% polyacrylamide gels, and proteins were separated by electrophoresis. The total protein amount in each sample was adjusted by staining with Gelcode Coomassie Blue Stain Reagent (Bie and Berntsen; Åbyhøj, Denmark) to calculate equal loading. The proteins of studied gels were electrotransferred onto nitrocellulose membranes (Hybond ECL RPN3032D; Amersham Bioscience, Little Chalfont, UK) for 1 hr at 100 V. The membranes were blocked with 5% milk in PBS-T (80 mM Na₂HPO₄, 20 mM NaH₂PO₄, 100 mM NaCl, pH 7.5, and 0.1% v/v Tween 20) for 1 hr. After washing, the membranes were incubated overnight at 5C with anti-AQPs antibody.

The membranes were washed and incubated with horseradish peroxidase (HRP)-conjugated goat antirabbit IgG secondary antibody (DAKO; Glostrup, Denmark) in PBS-T for 1 hr. After washing with PBS-T, the sites of antibody-antigen reaction were visualized with HRP-conjugated secondary antibodies (P448, diluted 1:3,000; DAKO) with an enhanced chemiluminescence (ECL) system (Amersham Bioscience) and exposed to photographic film (Hyperfilm ECL, RPN3103K; Amersham Bioscience).

IHC

Tissues were fixed by immersion in 4% paraformal-dehyde for 24 hr (Skowronski et al. 2007). For preparation of paraffin-embedded tissue sections (4 μm thickness), the tissues were dehydrated in ethanol, followed by xylene and finally embedded in paraffin. The sections were dewaxed and rehydrated. For immunoper-oxidase labeling, endogenous peroxidase was blocked by 0.5% H₂O₂ in absolute methanol for 10 min at room temperature. To reveal antigens, the sections were submerged in 1 mM Tris solution (pH 9.0) supplemented with 0.5 mM EGTA and heated in a microwave oven. After the treatment, the sections were left for 30 min in the buffer for cooling. Nonspecific binding of IgG was eliminated by incubating the sections in 50 mM NH₄Cl for 30 min, followed by blocking in PBS supplemented with 1% BSA, 0.05% saponin, and 0.2% gelatin. The sections were incubated overnight at 4C with primary antibodies diluted in PBS supplemented with 0.1% BSA and 0.3% Triton X-100. The sections were rinsed with PBS supplemented with 0.1% BSA, 0.05% saponin, and 0.2% gelatin and incubated with HRP-conjugated secondary antibody (DAKO). Labeling was visualized by 0.05% DAB. The microscopy was carried out using a DMRE light microscope (Leica; Heidelberg, Germany).

Results

IHC analysis using antibodies against nine AQPs (AQP1, 2, 3, 4, 5, 7, 8, 9, and 11) was performed to examine whether these water channel proteins are expressed in the female pig reproductive system. The analysis confirmed the expression of AQP1, AQP5, and AQP9. In contrast, no staining for other examined AQPs (AQP2, 3, 4, 7, 8, and 11) was observed in tested tissues (data not shown). The data obtained are presented in Figures 1-3 and summarized in Table 1.

AQP1 immunoreactivity was detected in the capillary endothelium of the ovary (Figure 1A). An identical labeling pattern was observed in the oviduct (Figure 1B) and uterus (Figure 1C). As a positive control, AQP1 labeling was seen in the apical and basolateral plasma membrane domains in the proximal tubule cells of pig kidney (Figure 1D), consistent with the previous findings in the kidneys of mice, rats, and humans (Nielsen et al. 1995; Maunsbach et al. 1997; Ma et al. 1998). Moreover, immunoblotting showed that anti-AQP1 antibody recognized a 29-kDa band in the ovary (Figure 1F, Lane 1), oviduct (Figure 1F, Lane 2), and uterus (Figure 1F, Lane 3) of the pig.

Figure 1

IHC staining of aquaporin (AQP)1 in paraffin-embedded sections of the ovary and uterus from pigs. Anti-AQP1 antibody labels capillary endothelium of the ovary (A), oviduct (B), and uterus (C). Arrows indicate localization of the vessels. Immunoperoxidase labeling of AQP1 from the pig kidney cortex (positive control) (D). The labeling is seen in both of the apical cell membrane and in the basolateral cell membrane in proximal tubule cells. No staining was observed in the absence of the primary antibody (E). (F) AQP1 antibody recognizes an ∼29-kDa band in protein samples from the pig ovary (Lane 1), oviduct (Lane 2), and uterus (Lane 3). FC, follicular cavity; L, lumen. Bar = 50 μm.

AQP5 was localized in granulosa cells and flattened follicle cells of the primordial follicles in the ovary (Figures 2A and 2B). In the oviduct, anti-AQP5 antibody labeled the cells of the muscles layer (Figure 2C) and luminal epithelial cells (Figure 2D). In the uterus, AQP5 was found in the smooth muscle cells (Figure 2E) and luminal and glandular epithelial cells (Figure 2F). As a positive control, AQP5 antibody noticeably stained (Figure 2G) the apical plasma membrane of the type I pulmonary epithelial cells of the pig, consistent with the previous findings seen in the lung tissues of mice, rats, and humans (Nielsen et al. 1997; Krane et al. 2001; Kreda et al. 2001). Imunoblotting showed that anti-AQP5 antibody recognized a 28-kDa band in the porcine ovary (Figure 2I, Lane 1), oviduct (Figure 2I, Lane 2), and uterus (Figure 2I, Lane 3).

AQP9 immunoreactivity was observed in the granulosa cells of the developing follicles in the ovary (Figure 3A). In the oviduct, AQP9 immunoreactivity was detected in the epithelial cells (Figure 3B). The anti-AQP9 antibody labeled the luminal and glandular epithelial cells of the uterus (Figure 3C). As a positive control, in agreement with the previous observation in the liver tissues of mice and rats (Carbrey et al. 2003; Rojek et al. 2007), AQP9 staining was seen at the sinusoidal surfaces of hepatocyte plates in the pig liver (Figure 3D). Immunoblotting also showed that the anti-AQP9 antibody recognized a 32-kDa band in the ovary (Figure 3F, Lane 1), oviduct (Figure 3F, Lane 2), and uterus (Figure 3F, Lane 3) of the pig.

Figure 2

IHC staining of AQP5 in paraffin-embedded sections of the ovary (A,B), oviduct (C,D), and uterus (E,F) from pigs. The immunoperoxidase staining is localized to flattened follicle cells of primordial follicles and granulosa cells of developing follicles (A,B). Anti-AQP5 antibody labels cells of muscles layer of the oviduct (C) and luminal epithelial cells (D). The antibody labels smooth muscle cells (E) and epithelial cells (F). The antibody noticeably stains apical membrane of type I pulmonary epithelial cells of the pig (positive control) (G). No staining was observed in the absence of the primary antibody (H). (I) AQP5 antibody recognizes an ∼28-kDa band in protein samples from the pig ovary (Lane 1), oviduct (Lane 2), and uterus (Lane 3). FC, follicular cavity; L, lumen. Bar = 50 μm.

Negative controls for all IHC analyses were performed by both omitting the primary antibodies specific to each AQP (Figures 1E, 2H, and 3E) and using non-immune IgG (data not shown), and no specific immunostaining was observed.

Discussion

In this study, IHC and immunoblotting showed that three isoforms of water channel proteins (AQP1, 5, and 9) are expressed in the pig ovary, oviduct, and uterus. In contrast, IHC showed no immunostaining for other examined AQPs (AQP2, 3, 4, 7, 8, and 11).

AQPs in Ovary

This study showed AQP1, 5, and 9 protein expression in the pig ovary: AQP1 in the capillary endothelium; AQP5 in the flattened follicle cells of primordial follicles and the granulosa cells of developing follicles; and AQP9 in the granulosa cells. AQPs have not been extensively studied in the ovary thus far, and this study provides the first evidence of AQP1 and AQP5 expression in ovarian tissues. The AQP9 expression has been previously shown in rat granulosa cells (McConnell et al. 2002); however, we showed the subcellular localization of AQP9 within the granulosa cells. In turn, Edashige et al. (2000) showed the mRNA expression of AQP3 and AQP7 in mouse oocytes. The presence of AQP3 at mRNA level in mouse oocytes was recently confirmed by Meng et al. (2008). In the mammalian ovary, the proper development of oocytes depends on the conditions provided by follicles including follicular fluid accumulation. This is why the transport of water in this organ seems to be an important process for the effective reproduction. Recently, AQP7, 8, and/or 9 have been shown to participate in water influx across the ovarian follicle wall primarily through transcellular transport mechanisms in the rat (McConnell et al. 2002). Importantly, AQP9 is the member of aquaglyceroporin subgroup, which is permeable not only to water but also to glycerol, urea, and other non-electrolytes. Hence, the expression of this AQP9 protein in granulosa cells may suggest that transport of above-mentioned substances is also important for the follicle development. In fact, AQP9 might ensure sufficient supply of granulosa cells with substrates (androgens) for estrogen production. Collectively, the expression of studied AQPs in the porcine ovary is confined to various compartments that are likely to be connected with their specific functions.

Figure 3

IHC staining of AQP9 in paraffin-embedded sections of the ovary (A), oviduct (B), and uterus (C) from pigs. Granulosa cells of developing follicles display immunoreactivity (A). AQP9 labels epithelial cells of the oviduct (B) and luminal and glandular epithelial cells of the uterus (C). Immunoperoxidase labeling of AQP9 from the pig liver (positive control) (D). No staining was observed in the absence of the primary antibody (E). (F) AQP9 antibody recognizes an ∼32-kDa band in protein samples from the pig ovary (Lane 1), oviduct (Lane 2), and uterus (Lane 3). FC, follicular cavity; L, lumen; CV, central vein. Bar = 50 μm.

AQPs in Oviduct

This study showed expression of AQP1, 5, and 9 in the porcine oviduct: AQP1 in the oviductal capillary, AQP5 in the muscle layer, and both AQP5 and AQP9 in the epithelial cells. In the literature thus far, there are two reports pertaining to AQP localization in oviductal tissues. Branes et al. (2005) showed by IHC the expression of AQP5, AQP8, and AQP9 in the epithelial cells of the rat oviduct. In turn, Gannon et al. (2000) found AQP1 labeling in the innermost and the inner cells of the circular muscular layer of the rat oviduct. These studies suggested that increased water movement into oviductal muscles through AQP1 could lead to muscle swelling that shuts down the lumen. These changes might be implicated in ovum transport toward the uterus. One of the hypotheses (tube locking) concerning the mechanism of ovum transport suggests that the ovum is delayed at the ampullaristhmic junction, probably as a result of muscle contraction, isthmic edema, and vascular distention (reviewed by Huang et al. 2006). In contrast, the pig oviductal muscles exhibited AQP5 expression but not AQP1. However, the expression of AQP1 was present in the pig oviductal vessels. Moreover, in oviductal luminal epithelium, AQP5 and AQP9 were localized. We therefore suggest that these three AQP isoforms (AQP1, 5, and 9) might participate in the epithelial fluid movement in the oviduct and/or the ovum transport toward the uterus.

AQPs in Uterus

In this study, we showed AQP1, 5, and 9 expression in the pig uterus. AQP1 expression was present in the endothelial cells of the blood vessels, AQP5 in the cells of myometrium, and both AQP5 and AQP9 in the cells of uterine epithelia. The first confirmation of AQP1 mRNA expression in the rat uterus was reported by Li et al. (1997). In 2003, two independent groups found AQP1 expression in mouse myometrium (Jablonski et al. 2003; Richard et al. 2003). Recently, Lindsay and Murphy (2006) reported AQP1 expression in endothelial cells of the endometrium and in the inner circular layer of myometrium of rats. Consistent with this, in this study, we showed the expression of AQP1 in the endothelial cells of the uterine blood vessels, whereas no expression was observed in the pig uterine epithelia or myometrium. The presence of AQP5 in the uterine epithelia has been previously shown in ovariectomized rats (Lindsay and Murphy 2006) and pregnant rats (Lindsay and Murphy 2007), as well as in mice during implantation (Richard et al. 2003). Here, we report AQP5 expression in the myometrium and the luminal and glandular epithelium of the pig uterus. Lindsay and Murphy (2007) showed AQP9 expression in the apical plasma membrane of the glandular epithelium of the rat uterus. In this study, AQP9 protein was detected in the glandular epithelium and additionally in the luminal epithelium of the pig uterus.

Table 1

Immunolocalization of aquaporin 1, 5, and 9 in the female pig reproductive system

	Ovary			Oviduct			Uterus
	Vessels	Primordial follicles	Granulosa cells	Vessels	Muscles	Luminal epithelium	Vessels	Muscles	Glandular epithelium	Luminal epithelium
Aquaporin 1	+			+			+
Aquaporin 5		+	+		+	+		+	+	+
Aquaporin 9			+			+			+	+

+, presence of aquaporins.

Recently, AQP2 expression was found in human endometrial cells of the uterus (He et al. 2006; Hildenbrand et al. 2006). In contrast, Jablonski et al. (2003) did not observe AQP2 in the ovariectomized mouse uterus, because this protein was strongly upregulated by estrogen in the uterine epithelial cells and myometrium (Jablonski et al. 2003). In this study, we did not localize AQP2 in the pig uterus, whereas anti-AQP2 antibody strongly labeled the apical cell membrane of inner medullary collecting ducts of the pig kidney as a positive control (data not shown). We suggest that specific localization of AQPs (AQP1, AQP5, and AQP9) in the cells of the pig uterus, particularly the presence of aquaporin (AQP5) and aquaglyceroporin (AQP9) in the uterine epithelial cells, might play an important role in the preparation of suitable environment for implantation of the embryo and nourishment of the embryo and fetus during pregnancy.

To our knowledge, this is the first IHC study pertaining to the expression of AQPs in the female reproductive system in pigs. These results suggest the role of AQPs in water homeostasis within tissues of the porcine ovary, oviduct, and uterus. Further studies are necessary to establish the physiological role of these proteins in relation to reproductive processes in the pig.

Footnotes

Acknowledgements

This research was supported by the Polish Ministry of Science and Higher Education (Grants N N308 0042 33 and 0206.0805).

The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work. The authors thank Prof. Stanislaw Okrasa for comments and suggestions.

References

Akins

Morrissette

(1968) Gross ovarian changes during estrous cycle of swine. Am J Vet Res 29:1953–1957

Branes

Morales

Rios

Villalon

(2005) Regulation of the immunoexpression of aquaporin 9 by ovarian hormones in the rat oviductal epithelium. Am J Physiol Cell Physiol 288: C1048–1057

Carbrey

Gorelick-Feldman

Kozono

Praetorius

Nielsen

Agre

(2003) Aquaglyceroporin AQP9: Solute permeation and metabolic control of expression in liver. Proc Natl Acad Sci USA 100:2945–2950

Edashige

Sakamoto

Kasai

(2000) Expression of mRNAs of the aquaporin family in mouse oocytes and embryos. Cryobiology 40:171–175

Elkjaer

Nejsum

Gresz

Kwon

T-H

Jensen

Frokiaer

Nielsen

(2001) Immunolocalization of aquaporin-8 in rat kidney, gastrointestinal tract, testis, and airways. Am J Physiol Renal Physiol 281:F1047–1057

Gannon

Warnes

Carati

Verco

(2000) Aquaporin-1 expression in visceral smooth muscle cells of female rat reproductive tract. J Smooth Muscle Res 36:155–167

Gorelick

Praetorius

Tsunenari

Nielsen

Agre

(2006) Aquaporin-11: a channel protein lacking apparent transport function expressed in brain. BMC Biochem 7:14

Sheng

Luo

Jin

Wang

Qian

Zhou

. (2006) Aquaporin-2 expression in human endometrium correlates with serum ovarian steroid hormones. Life Sci 79:423–429

Hildenbrand

Lalitkumar

Nielsen

Gemzell-Danielsson

Stavreus-Evers

(2006) Expression of aquaporin 2 in human endometrium. Fertil Steril 86:1452–1458

10.

Huang

Sun

Zhang

Meng

(2006) Function of aquaporins in female and male reproductive systems. Hum Reprod Update 12:785–795

11.

Ishikawa

Cho

Yuan

Skowronski

Pan

Ishida

(2006) Water channels and zymogen granules in salivary glands. J Pharmacol Sci 100:495–512

12.

Jablonski

McConnell

Hughes

Jr Huet-Hudson

(2003) Estrogen regulation of aquaporins in the mouse uterus: potential roles in uterine water movement. Biol Reprod 69:1481–1487

13.

Kim

Gresz

Rojek

Wang

Verkman

Frokier

Nielsen

(2005) Decreased expression of AQP2 and AQP4 water channels and Na, K-ATPase in kidney collecting duct in AQP3 null mice. Biol Cell 97:765–778

14.

Krane

Fortner

Hand

McGraw

Lorenz

Wert

Towne

. (2001) Aquaporin 5-deficient mouse lungs are hyperresponsive to cholinergic stimulation. Proc Natl Acad Sci USA 98:14114–14119

15.

Kreda

Gynn

Fenstermacher

Boucher

Gabriel

(2001) Expression and localization of epithelial aquaporins in the adult human lung. Am J Respir Cell Mol Biol 24:224–234

16.

Koide

(1994) The water channel gene in human uterus. Biochem Mol Biol Int 32:371–377

17.

Koide

(1997) Regulation of water channel gene (AQP-CHIP) expression by estradiol and anordiol in rat uterus. Yao Xue Xue Bao 32:586–592

18.

Lindsay

Murphy

(2006) Redistribution of aquaporins 1 and 5 in the rat uterus is dependent on progesterone: a study with light and electron microscopy. Reproduction 131:369–378

19.

Lindsay

Murphy

(2007) Aquaporins are upregulated in glandular epithelium at the time of implantation in the rat. J Mol Histol 38:87–95

20.

Yang

Gillespie

Carlson

Epstein

Verkman

(1998) Severely impaired urinary concentrating ability in transgenic mice lacking aquaporin-1 water channels. J Biol Chem 273:4296–4299

21.

Maunsbach

Marples

Chin

Ning

Bondy

Agre

Nielsen

(1997) Aquaporin-1 water channel expression in human kidney. J Am Soc Nephrol 8:1–14

22.

McConnell

Yunus

Gross

Bost

Clemens

Hughes

Jr (2002) Water permeability of an ovarian antral follicle is predominantly transcellular and mediated by aquaporins. Endocrinology 143:2905–2912

23.

Meng

Gao

Dong

Sheng

Huang

(2008) Reduced expression and function of aquaporin-3 in mouse metaphase-II oocytes induced by controlled ovarian hyper-stimulation were associated with subsequent low fertilization rate. Cell Physiol Biochem 21:123–128

24.

Nejsum

Elkjaer

M-L

Hager

Frøkiaer

Kwon

Nielsen

(2000) Localization of aquaporin-7 in rat and mouse kidney using RT-PCR, immunoblotting, and immunocytochemistry. Biochem Biophys Res Commun 277:164–170

25.

Nielsen

Kwon

T-H

Praetorius

Frøkiaer

Knepper

Nielsen

(2006) Aldosterone increases urine production and decreases apical AQP2 expression in rats with diabetes insipidus. Am J Physiol Renal Physiol 290:F438–449

26.

Nielsen

King

Christensen

Agre

(1997) Aquaporins in complex tissues. II. Subcellular distribution in respiratory and glandular tissues of rat. Am J Physiol 273:C1549–1561

27.

Nielsen

Pallone

Smith

Christensen

Agre

Maunsbach

(1995) Aquaporin-1 water channels in short and long loop descending thin limbs and in descending vasa recta in rat kidney. Am J Physiol 268:F1023–1037

28.

Preston

Agre

(1991) Isolation of the cDNA for erythrocyte integral membrane protein of 28 kilodaltons: member of an ancient channel family. Proc Natl Acad Sci USA 88:11110–11114

29.

Richard

Gao

Brown

Reese

(2003) Aquaporin water channel genes are differentially expressed and regulated by ovarian steroids during the periimplantation period in the mouse. Endocrinology 144:1533–1541

30.

Rojek

Skowronski

Fuchtbauer

Fenton

Agre

Frokiaer

. (2007) Defective glycerol metabolism in aquaporin 9 (AQP9) knockout mice. Proc Natl Acad Sci USA 104:3609–3614

31.

Skowronski

Lebeck

Rojek

Praetorius

Fuchtbauer

Frokiaer

Nielsen

(2007) AQP7 is localized in capillaries of adipose tissue, cardiac and striated muscle: implications in glycerol metabolism. Am J Physiol Renal Physiol 292:F956–965

32.

Terris

Ecelbarger

Nielsen

Knepper

(1996) Long-term regulation of four renal aquaporins in rats. Am J Physiol 271: F414–422

33.

Vajda

Pedersen

Fuchtbauer

Wertz

Stodkilde-Jorgensen

Sulyok

Doczi

. (2002) Delayed onset of brain edema and mislocalization of aquaporin-4 in dystrophin-null transgenic mice. Proc Natl Acad Sci USA 99:13131–13136

34.

Verkman

Mitra

(2000) Structure and function of aquaporin water channels. Am J Physiol Renal Physiol 278:F13–28

Immunolocalization of Aquaporin 1,5,and 9 in the Female Pig Reproductive System

Abstract

Keywords

Materials and Methods

Experimental Animals

Primary Antibodies

SDS-PAGE and Immunoblotting

IHC

Results

Discussion

AQPs in Ovary

AQPs in Oviduct

AQPs in Uterus

Footnotes

Acknowledgements

References