The effect of racemomycin-D, a nephrotoxic antibiotic, on cellular metabolism of rat kidney cortex in vitro.

In vitro effects of racemomycin-D on cellular metabolism were examined in rat kidney. Racemomycin-D decreased the concentration gradient of Na+ and K+ across the cell membranes, but failed to influence water content and ATP concentration of kidney cortical slices. The antibiotic inhibited microsomal (Na+ + K+)-ATPase. Preincubation of the microsomes with racemomycin-D enhanced the inhibition about 1.8-fold. Succinoxidase activity of mitochondria remained unaltered in the presence of racemomycin-D, but the antibiotic potently decreased ATP-dependent Ca2+ and Mg2+ uptakes by mitochondria. These results suggest that racemomycin-D probably disorders intracellular homeostasis of Na+, K+ and Ca2+.