Effect of renal vein ligation with or without suprarenal inferior vena cava ligation on sodium and phosphate excretions during acute extracellular volume expansion in the rat.

Right nephrectomy with or without inferior vena cava (IVC) ligation was performed in rats 1 week after left renal vein ligation. Left kidney function and sodium and phosphate excretions by volume expansion were investigated. Inulin (CIN) and para-aminohippuric acid (CPAH) clearances and fractional excretions of sodium (FENa) and phosphate (FEP) were examined before and after volume expansion was induced by normal saline. Kidney functions were well preserved with development of collateral venous channels; biochemical parameters returned to the normal ranges. However, CIN and CPAH were reduced to 33 to 25 per cent of control values and the filtration fraction was elevated. After volume expansion, a marked increment of FENa was observed in cases of IVC ligation but the increment in animals without IVC ligation was less than in the control group. FEP was also increased in experimental groups but the magnitude of phosphaturia was not so prominent compared to the control group. The increment of FEP was not comparable to that of FENa. Thus, from the aspect of kidney function, this experiment showed the rationality of left renal vein ligation with contralateral nephrectomy. From the pathophysiologic aspect, the magnitude of natriuresis and phosphaturia by volume expansion was not prominent and a reduced reabsorptive capacity for sodium and phosphate may exist in a solitary kidney with a ligated renal vein. When suprarenal IVC ligation was also done, prominent natriuresis was observed with saline infusion.