Play all audios:
Since the low RPF appears to be due mainly to active vaso-constriction, the question is raised whether renal vaso-constriction is needed to minimize the energy demands of the kidney in early
postnatal life. The work load to the kidney is determined by the GFR. The most energy demanding process of the kidney is reabsorption of Na (TNa). In the present study the relationship
between TNa and 02 consumption are compared in the immature kidney of 24 days old rats (R24) and the mature kidney of 45 days old rats (R 45). Determinations are made of filtered Na (FNa),
TNa and 02 consumption by extraction and clearance techniques during hyeropenia (HP) and volume expansion (VE). The two conditions are chosen since VE will cause vaso-dilatation of the
immature kidney. This finding was confirmed in the present study and resulted (see table) in a marked increase of TNa in volume expanded R24.
Yet the increase in 02 consumption during the transition from HP to VE was less pronounced in R24 than in R45. In volume expanded R24 the amount of TNa/μmol oxygen consumed (Na-02) increased
significantly. This suggests that in the volume expanded R24 the increased tubular load of sodium is reabsorbed by non oxidative pathways, either passive or anaerobic.
Anyone you share the following link with will be able to read this content: