Expression and nephron segment-specific distribution of major renal aquaporins (AQP1-4) in Equus caballus, the domestic horse

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2007-07, Vol.293 (1), p.R492-R503
• Main Authors: Floyd, R. V, Mason, S. L, Proudman, C. J, German, A. J, Marples, D, Mobasheri, A
• Format: Article
• Language: English
• Subjects: Animals; Antibody Specificity; Aquaporins - metabolism; Blotting, Western; Comparative studies; Electrophoresis, Polyacrylamide Gel; Gene expression; Horses; Horses - metabolism; Immunohistochemistry; Kidney - metabolism; Kidney Tubules - metabolism; Kidney Tubules, Collecting - metabolism; Kidneys; Membranes; Nephrons - metabolism; Oligonucleotide Array Sequence Analysis; Peptides - metabolism; Proteins; Rats
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00689.2005

1 Department of Physiology, 2 Department of Veterinary Preclinical Sciences, 3 Equine Division, and 4 Division of Small Animal Studies, Faculty of Veterinary Science, University of Liverpool, Liverpool; 5 Institute of Membrane and Systems Biology, University of Leeds, Leeds; and 6 Division of Veterinary Medicine, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, United Kingdom Submitted 23 September 2005 ; accepted in final form 9 April 2007 Aquaporins (AQPs) play fundamental roles in water and osmolyte homeostasis by facilitating water and small solute movement across plasma membranes of epithelial, endothelial, and other tissues. AQP proteins are abundantly expressed in the mammalian kidney, where they have been shown to play essential roles in fluid balance and urine concentration. Thus far, the majority of studies on renal AQPs have been carried out in laboratory rodents and sheep; no data have been published on the expression of AQPs in kidneys of equines or other large mammals. The aim of this comparative study was to determine the expression and nephron segment localization of AQP1–4 in Equus caballus by immunoblotting and immunohistochemistry with custom-designed rabbit polyclonal antisera. AQP1 was found in apical and basolateral membranes of the proximal convoluted tubules and thin descending limbs of the loop of Henle. AQP2 expression was specifically detected in apical membranes of cortical, medullary, and papillary collecting ducts. AQP3 was expressed in basolateral membranes of cortical, medullary, and papillary collecting ducts. Immunohistochemistry also confirmed AQP4 expression in basolateral membranes of cells lining the distal convoluted and connecting tubules. Western blots revealed high expression of AQP1–4 in the equine kidney. These observations confirm that AQPs are expressed in the equine kidney and are found in similar nephron locations to mouse, rat, and human kidney. Equine renal AQP proteins are likely to be involved in acute and chronic regulation of body fluid composition and may be implicated in water balance disorders brought about by colic and endotoxemia. equine; aquaporin; tissue microarrays; immunohistochemistry Address for reprint requests and other correspondence: A. Mobasheri, Division of Veterinary Medicine, School of Veterinary Medicine and Science, Univ. of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD (e-mail: ali.mobasheri{at}nottingham.ac.uk )