Support of hypoxic renal cell volume regulation by glycine

PO2 declines to less than 10 mm Hg in local regions of the renal cortex. Amino acids seem to modify the hypoxic tolerance of renal cells. It was suggested that glycine may support renal function in hypoxia. Aim of the present study was to test the effect of glycine on renal cellular hypoxic tolerance. We isolated tubules of the rat kidney cortex (ITS) by collagenase treatment and measured cellular function at different levels of extracellular oxygen tensions (1, 2.5, 5, 10, 40, and 100 mm Hg) both with and without glycine in the incubation medium. No significant effects were observed in the "physiological" range at an extracellular PO2 = 100-10 mm Hg. With no glycine in the incubation medium, the outer tubular diameter of ITS rose at lower oxygen tensions, at PO2 of 1 mm Hg by about 170%, and the loss of 4 marker enzymes increased about 2-4 fold. Hypoxic lactate formation increased at extracellular oxygen tensions less than 10 mm Hg. Intracellular K+ fell in parallel to about one third of the aerobic control values. Addition of glycine to the incubation medium did not significantly change intracellular K+ or anaerobic lactate formation. In contrast, the loss of marker enzymes was significantly suppressed by glycine, lysosomal APase and mitochondrial GlDH by about 30%, cytoplasmatic LDH and brush border tau GT by about 50%. Accordingly, at PO2 = 1 mm Hg the hypoxic swelling of renal cells was suppressed in the presence of glycine by about 50%.(ABSTRACT TRUNCATED AT 250 WORDS)