RESUMEN
The effects of acute renal failure on the impeded (IER) and unimpeded (UER) eruption dental rate and attrition rate (AR) were investigated. Adult female Wistar rats were injected with 125 mg/kg b.w of human methemoglobin (M-Hb) in order to induce a first episode of hemodynamically-mediated acute renal failure (H-ARF). Ten days after the injection of M-Hb, other groups of rats received another equal dose of the drug in order to induce a second episode of H-ARF. A group of six animals was pair-fed daily and individually with rats of M-Hb groups. Evaluation of renal function, histopathology studies, IER, UER, food intake (FI), AR and body weight gains was performed at different times after the first and second injections, of M-Hb. Treatment induced transient increases in plasma urea concentration and urine volume, and significant depression in urine osmolality, body weight gains, IER, UER and AR. In every case, the maximal effect of the first injection of M-Hb on the individual parameters was always greater than that of the second injection. Histologic sections showed interstitial cellular infiltration, desquamation of the proximal tubular epithelium and collapse or dilation of the tubular lumen. The functional values of kidney, histologic findings, IER, UER and AR of the pair-fed rats were not significantly different from control values. The results of the present study indicate that dental eruption rate (IER and UER) is relatively low in uremic rats with kidney tubule lesions and that both parameters are related.
RESUMEN
The effects of acute renal failure on the impeded (IER) and unimpeded (UER) eruption dental rate and attrition rate (AR) were investigated. Adult female Wistar rats were injected with 125 mg/kg b.w of human methemoglobin (M-Hb) in order to induce a first episode of hemodynamically-mediated acute renal failure (H-ARF). Ten days after the injection of M-Hb, other groups of rats received another equal dose of the drug in order to induce a second episode of H-ARF. A group of six animals was pair-fed daily and individually with rats of M-Hb groups. Evaluation of renal function, histopathology studies, IER, UER, food intake (FI), AR and body weight gains was performed at different times after the first and second injections, of M-Hb. Treatment induced transient increases in plasma urea concentration and urine volume, and significant depression in urine osmolality, body weight gains, IER, UER and AR. In every case, the maximal effect of the first injection of M-Hb on the individual parameters was always greater than that of the second injection. Histologic sections showed interstitial cellular infiltration, desquamation of the proximal tubular epithelium and collapse or dilation of the tubular lumen. The functional values of kidney, histologic findings, IER, UER and AR of the pair-fed rats were not significantly different from control values. The results of the present study indicate that dental eruption rate (IER and UER) is relatively low in uremic rats with kidney tubule lesions and that both parameters are related.
RESUMEN
Adult female Wistar rats were injected with 125 mg/kg b.w. of human methemoglobin (M-Hb) in order to induce a first episode of hemodynamically-mediated acute renal failure (HMARF). Eleven days after the injection of M-Hb, other groups of rats received another equal dose of the drug in order to induce a second episode of HMARF. Evaluation of renal function, histopathology studies, and determinations of plasma and kidney erythropoietin (Epo) titers by radioimmunoassay in normoxic and hypoxic conditions were performed 1, 2, 3, 5 and 10 days after M-Hb administration. Treatment induced transient increases in plasma urea concentration, fractional sodium excretion, and urine volume, and significant depression in urine osmolality. In every case, the maximal effect of the first injection of M-Hb on the individual parameters was always greater than that of the second injection, and observed on the 5th post-injection day. Histologic sections showed interstitial cellular infiltration, desquamation of the proximal tubular epithelium and collapse or dilation of the tubular lumen. Treatment with M-Hb depressed Epo titers in both kidney homogenates and plasma in normoxic as well as hypoxic rats. Here again, the effect of the first injection of the drug was higher than that of the second one. These observations indicate that there is a negative correlation between kidney tubule injury and Epo production in normoxic and hypoxic conditions. The findings give support to the concept that Epo production is related to proximal tubular function.