ENERGY METABOLISM IN HYDRONEPHROTIC KIDNEYS

Fundamental Study in Rat Hydronephrotic Kidneys

Abstract

This study was undertaken to determine the effects of unilateral ureteral obstruction on the renal tissue levels of adenine nucleotides in order to elucidate the mechanisms underlying the hydronephrosis and how such changes may be recovered after relief of obstruction.
Ureteral obstruciton with hydronephrosis was produced by ligation of a unilateral ureter in Wistar rats. Before and at 6 months after the operation, measurement of adenine nucleotides (ATP, ADP and AMP) was performed according to the method of Nagata and Rusmussen. Calculation of energy charge was made by Atkinson's formula. The levels of inorganic phosphate (Pi) and its specific activity (S. A.) were calculated from ³²P-orthophosphate incorporation. The same procedures were adopted after complete relief of ureteral obstruction lasting for 1, 2, 3, 4, 5 and 6 months. Shamoperated controls were also observed.
The results revealed that the level of ATP sharply decreased to about 60% of normal one month after ureteral ligation with a further decline continuing up to 6 months. ADP and AMP showed a mild decrease. Cell Pi and its S. A. increasd during these periods. Recovery of the nucleotides after relief of ligation was prominent in the group with 1 and 2 months' ligation. A longer period of ligation, however, prevent the nucleotides from reaching the former levels. The levels of energy charge during the periods of ureterla obstruction and its relief did not show any significant change.
These results suggest that, there is positive relationship between the progress of hydronephrosis and decrease of ATP, and after ureteral obstruction in excess 3 months, complete recovery of ATP-generating system could not take place. This probably reflected irreversible chnages in the energyreguiring system of kidney.