ABSTRACT
To assess the importance and role of cellular energetics in processes leading to chemically or pathologically induced nephrotoxicity, it is first necessary to consider the role of energy metabolism in maintaining normal renal function. Energy-requiring processes in the kidneys can be divided into three categories: glomerular filtration, membrane transport processes, and biosynthetic reactions. For the tubular epithelial cells, only the last two processes are relevant. Membrane transport includes primary and secondary active transporters on renal brush-border and basolateral plasma membranes for inorganic ions and metabolites, and encompasses both reabsorptive and secretory processes. The energy-dependent, biosynthetic reactions include the biosynthesis of macromolecules (i.e., protein, DNA, RNA, lipid), the biosynthesis of specialized products, such as erythropoietin and vitamin D, and drug metabolism reactions. All of the above mentioned processes are either directly or indirectly dependent on an adequate supply of ATP (Soltoff, 1986), and are illustrated schematically in Figure 11.1. The large array of transport and biosynthetic processes in the renal tubular epithelium
that require ATP implies that maintenance of an adequate supply of ATP is essential for proper renal function and that conditions that deplete ATP or otherwise interfere with its production or utilization will lead to a loss of renal function and toxicity.
