Interactions between Inorganic Phosphate and Energy Metabolism in Renal Cortical Tubules

Abstract

Inorganic phosphate interacts with essentially all major metabolic pathways, primarily through the phosphorylation of intermediates via ATP or other nucleotides. In this regard, oxidative phosphorylation has an absolute requirement for inorganic phosphate (1) but it is not certain whether phosphate under certain conditions may regulate or control mitochondrial respiration. It is generally believed that mitochondrial respiration is determined by the extramitochondrial concentration ratio of [ADP]/[ATP]. On the other hand, Wilson et al (2) have advanced the concept that mitochondrial respiration may be governed by the extramitochondrial activities of inorganic phosphate as well as ADP and ATP. It is clear that inorganic phosphate is important for mitochondrial anion transport processes that facilitate the transfer of reducing equivalents between cytosolic and mitochondrial compartments (3). In view of these considerations, we performed a series of studies that examine the interactions between phosphate and respiration in renal cortical tubules.