The role of tubular necrosis in the pathophysiology of acute renal failure

Acute alterations of tissue Ca++ and lethal tubular cell injury during HgCl2 nephrotoxicity in the rat

The relationship between acute alterations of tissue Ca++ and the development of acute renal failure and lethal renal tubular cell injury in the kidney was studied. Nephrotoxicity was induced by HgCl2, and its course was modified by prior saline drinking. Both a semiquantitative scale measuring the extent of lethal tubule cell injury and a computerized assessment of numbers of nuclei in Feulgen stained sections of cortex were used for morphologic analysis. The 2 methods agreed very closely with each other, indicating the utility of an automated computerized approach as a rapid, quantitative adjunct for the assessment of lethal cell injury in the kidney. Increases of blood urea nitrogen during 12-24 hr after HgCl2 were associated with increasing extent of lethal cell injury in both saline and water drinking rats. Striking progressive increases of renal cortical Ca++ developed. In both water and saline drinking rats, the increases in tissue Ca++ were significantly associated with increasing blood urea nitrogen levels and extent of lethal cell injury as determined morphologically. However, similar degrees of increased blood urea nitrogen and extensive lethal cell injury were accompanied by substantially lower tissue Ca++ levels in saline drinking rats than in water drinking rats, indicating an independent effect of saline drinking to ameliorate the increases in tissue Ca++ occurring during lethal cell injury in this model. These data provide further insight into the relationship between structural and functional changes during HgCl2 nephrotoxicity and establish the utility of an automated computerized morphometric method for assessing the extent of lethal cell injury.

Hypokalemic rhabdomyolysis with myoglobinuria due to licorice ingestion and diuretic treatment

A 54-year-old man was admitted to hospital with acute rhabdomyolysis and myoglobinuria due to hypokalemia. The hypokalemia was due to chronic licorice ingestion and diuretic treatment. The myoglobinemia led to a glomerulopathy and tubulopathy. There was, however, no clinical evidence of acute renal failure (ARF). We propose that the volume expansion caused by the steroid-like actions of licorice might have prevented the development of an ARF.

Sodium-chloride-induced protection in nephrotoxic acute renal failure: independence from renin

It has been shown that the severity of experimentally induced acute renal failure (ARF) is inversely related to dietary sodium chloride intake, and the effects have been attributed to the concurrent changes in renal renin. In the current study, renal renin of rats was increased by chronic sodium deprivation and decreased by chronic sodium loading and DOCA administration. In two nephrotoxic models (mercuric chloride, uranyl nitrate), giving previously sodium-deprived rats 1% sodium chloride to drink for 48 hours prior to ARF induction greatly attenuated the severity without any reduction in their high renal renin. Conversely, giving previously sodium-loaded rats tap water to drink for 4 to 5 days prior to AFR induction greatly enhanced the severity without any increase in their subnormal renal renin. Therefore, the changes in severity of ARF resulting from changes in dietary sodium are not mediated by changes in renal renin. Significant inverse correlations were found between mean peak BUN values during the follow-up period (5 to 7 days) and the 24-hour urinary sodium excretions prior to ARF induction in both models, suggesting that sodium intake and/or excretion at the time of induction is a good predictor of the severity. The effects of sodium chloride in both models were predominantly expressed during the maintenance phase, and consisted of attenuation of the severity (both models) and hastening of the recovery (mercuric chloride model). Possible mechanisms by which dietary sodium produced its effects, independently of its effects on the renin-angiotensin system, are discussed.

In vitro uptake of gentamicin by rat renal cortical tissue

The mechanism of gentamicin uptake in vitro by renal cortical slices of rat kidney was investigated. The cortical-slice-uptake ratio of gentamicin concentration in 1.0 g of tissue water to that of 1.0 ml of incubation medium (SW/M) was 1.44 +/- 0.04. The uptake of gentamicin was inhibited by 2 x 10(-5) M dinitrophenol (SW/M = 1.03 +/- 0.04) and by anoxia (SW/M = 1.01 +/- 0.04). The results indicate that aerobic phosphorylation is required to transport gentamicin into the cells. The uptake of p-aminohippurate and tetraethylammonium chloride by renal cortical slices was not affected by gentamicin.