IMMATURE TUBULES ARE TOLERANT OF OXYGEN DEPRIVATION

The tolerance of immature tissues to injury has been noted over the pa st several decades. Traditional teaching relates this tolerance to ene rgy derived from anaerobic glycolysis. This mini-review describes inve stigations of the hypothesis that the immature kidney is less suscepti ble to oxygen deprivation than the mature kidney. Utilizing proximal t ubule suspensions from immature and mature rats, studies assessing ATP levels as an index of cellular energy and lactate dehydrogenase (LDH) release as a determinant of plasma membrane damage demonstrate the de veloping kidney is resistant to prolonged anoxia. ATP is maintained at twofold higher levels during anoxia in the immature tubule compared w ith the mature tubule. The contribution of anaerobic glycolysis to the tolerance of the immature renal tubules is investigated by two inhibi tors of the glycolytic pathway, L-glucose and iodoacetate. Following 7 0%-90% inhibition of glycolysis, ATP is decreased to similar levels in immature and mature tubules. However, immature tubules remain resista nt to anoxic damage with no significant change in LDH release. Therefo re, enhanced glycolytic activity does not play a dominant role in the tolerance of the developing kidney to anoxia, and this tolerance is no t primarily dependent on preservation of cellular ATP.