Renal sodium transport and oxygen consumption

Abstract

Glomerular filtration rate and renal blood flow were increased in dogs by infusion of 2% glycine and hypertonic NaCl at rates of 8 ml/min. This procedure resulted both in an increased rate of sodium reabsorption and in increased oxygen consumption. Approximately six equivalents of sodium were transported per equivalent oxygen consumed, a ratio similar to that obtained by others when glomerular filtration rate had been reduced. These observations strongly suggest that a large part of renal oxygen consumption is related to the transport of sodium. When the rate of sodium reabsorption was reduced during mannitol diuresis, arteriovenous oxygen difference decreased, but renal oxygen consumption remained unchanged. It is suggested that the active sodium transport in the proximal tubules continues at an unchanged rate during mannitol diuresis but that net reabsorption is reduced owing to increased passive influx into the tubular lumen when the transtubular concentration gradient increases. Other interpretations are discussed.