Ontogeny of phosphate transport by rat liver plasma membrane vesicles

F. K. Ghishan, W. Dykes

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The present studies were designed to characterize the developmental aspects of Na+-dependent phosphate transport, across the hepatocyte basolateral membranes of the suckling and weanling rats. A well validated technique of plasma membrane vesicles (BLMV) was utilized. Phosphate uptake was driven into an osmotically active intravesicular space as evident by a linear relationship between uptake and 1/osm with no binding component y = 0.04 x-0.03, r2 = 0.99 and y = 0.035 x +0.01, r2 = 0.95 in suckling and weanling BLMV's respectively. The presence of inwardly directed Na+ and pH gradient stimulated phosphate uptake in suckling and weanling BLMV's, however, uptake values under Na+ and pH gradients were greater in weanling rats compared to suckling rats. Kinetics of Na+-dependent phosphate uptake were 0.14 ± 0.01 and 0.28 ± 0.035 at pH 6.1 (P < 0.05) and 0.1 ± 0.007 and 0.15 ± 0.03 nmoles/mg protein/10s (P < 0.05) at pH 7.4 in suckling and weanling rats respectively. K(m) values were not significantly different. Na+ arsenate and phosphonoformonic acid inhibited Na+-dependent phosphate uptake, whereas ATP and P-MB (para-chlomercuribenzoic acid) did not effect Na+-dependent phosphate uptake. These studies demonstrate for the first time the presence of a specialized transport system for phosphate across the basolateral membranes of the rat liver during development. This transport system exhibit ontogenic characteristics in regard to its transport capacity.

Original languageEnglish (US)
Pages (from-to)197-201
Number of pages5
JournalJournal of Developmental Physiology
Volume19
Issue number5
StatePublished - Dec 1 1993
Externally publishedYes

ASJC Scopus subject areas

  • Developmental Biology
  • Physiology

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