Early lithium-induced nephrotoxicity and changes of renal hemodynamics in rats

In adult female rats, 2-day pretreatment as well as acute lithium administration led to changes of several functional renal parameters indicating early signs of nephrotoxicity. The infection of lithium (0.3 mmol/100 g b.wt., ip.) provoked a statistically significant decrease of the glomerular filtration rate (creatinine clearance), fractional tubular sodium reabsorption and the excretion of hydrogen ions, whereas blood urea nitrogen concentrations, the renal excretion of potassium and p-aminohippurate were enhanced during the test periods. This lithium-induced damage of kidney functions parallels with alterations in renal hemodynamics (86Rb method). Especially following subacute lithium treatment the normally higher cortical blood flow distribution in the kidney shifted to the medullary regions (OMBF, IMBF), because the intrarenal resistance was diminished there. The results represented, however, must be interpreted in that way that not always a strong correlation between the lithium-induced alterations of renal elimination functions and the changes in renal blood flow distribution could be proved.