QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online May 13, 2004
Journal of Experimental Biology 207, 2055-2064 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00971

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sugiura, S. H. Articles by Ferraris, R. P. Search for Related Content PubMed PubMed Citation Articles by Sugiura, S. H. Articles by Ferraris, R. P. Social Bookmarking                         What's this?

Contributions of different NaPi cotransporter isoforms to dietary regulation of P transport in the pyloric caeca and intestine of rainbow trout

Shozo H. Sugiura and Ronaldo P. Ferraris^*

New Jersey Medical School, Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA

^* Author for correspondence (e-mail: Ferraris{at}umdnj.edu)

Accepted 10 March 2004

The anatomical proximity and embryological relationship of the pyloric caeca (PC) and small intestine of rainbow trout has led to the frequent assumption, on little evidence, that they have the same enzymes and transporters. In trout, the PC is an important absorptive organ for dietary nutrients, but its role in dietary P absorption has not been reported. We found that apical inorganic phosphate (Pi) transport in PC comprises carrier-mediated and diffusive components. Carrier-mediated uptake was energy- and temperature-dependent, competitively inhibited and Na⁺-independent, and greater than the Na⁺-dependent intestinal uptake. Pi uptake in PC was pH-sensitive in the presence of Na⁺. Despite the active Pi transport system in PC, high postprandial luminal Pi concentrations (20 mmol l^–1) indicate that diffusive uptake represents 92% of total Pi uptake in PC of fed fish. The nucleotide sequence of a sodium-phosphate cotransporter (NaPi-II) isoform isolated from PC was 8% different from the intestinal NaPi cotransporter. PC-NaPi mRNA was abundant in PC but rare in the intestine, whereas intestinal NaPi mRNA was abundant in the intestine but scarce in PC. Dietary P restriction reduced serum and bone P concentrations, increased intestine-type, but not PC-type, NaPi mRNA in PC, and increased Pi uptake in intestine but not in PC. Intestine-type NaPi expression may be useful for predicting dietary P deficiency.

Key words: NaPi cotransport, phosphorus, rainbow trout, pyloric caeca, intestine

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. Kirchner, A. Muduli, D. Casirola, K. Prum, V. Douard, and R. P Ferraris Luminal fructose inhibits rat intestinal sodium-phosphate cotransporter gene expression and phosphate uptake Am. J. Clinical Nutrition, April 1, 2008; 87(4): 1028 - 1038. [Abstract] [Full Text] [PDF]

				S. H. Sugiura, P. K. Roy, and R. P. Ferraris Dietary acidification enhances phosphorus digestibility but decreases H+/K+-ATPase expression in rainbow trout J. Exp. Biol., October 1, 2006; 209(19): 3719 - 3728. [Abstract] [Full Text] [PDF]

				S. H. Sugiura and R. P. Ferraris Dietary phosphorus-responsive genes in the intestine, pyloric ceca, and kidney of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2004; 287(3): R541 - R550. [Abstract] [Full Text] [PDF]