ALUMINUM ACCUMULATION IN SOME TISSUES OF RATS WITH COMPROMISED KIDNEY-FUNCTION INDUCED BY CADMIUM-METALLOTHIONEIN

Two experiments (I and II) were performed to study aluminium accumulat ion in brain as well as in several other tissues in male Wistar rats. A single intraperitoneal injection of cadmium-metallothionein (CdMT, 0 .1-0.4 mg Cd/kg b.wt.) was used to compromise kidney function 12 hr be fore the final aluminium injection in both experiments. In experiment I, rats were maintained on diets deficient (0.01%, w/w) in calcium (-C a) or providing adequate (+Ca) dietary calcium (0.9%) for 6 weeks. Amo ng animals given a daily intraperitoneal dose of aluminium chloride (1 0.8 mg Al/kg per day) on 6 consecutive days there was a tendency towar ds higher aluminium level in brains of rats with compromised kidney fu nction from CdMT (in -Ca rats: the geometric mean [G]=288 versus 205 n g/g wet weight [w., wt.], P=0.07, and in +Ca rats: G=242 versus 164, P <0.05) as compared to animals given no CdMT. The results from experime nt II (all rats were given aluminium 5.6 mg Al/kg 2 and 12 hr after Cd MT injection) demonstrated a higher level of aluminium (G: 41 ng/g w. wt., P<0.05) in brains of rats with only slightly damaged kidney funct ion (0.1 mg Cd/kg) than in those given no CdMT (G: 29 ng/g w. wt.). It was also observed that 1) calcium deficiency had a statistically sign ificant effect (P<0.05) in increasing kidney retention of intraperiton eal aluminium (G: 327 mu g/g w wt.) as compared to rats with a normal calcium supply in the diet (G: 54 mu g/g w. wt.); 2) when aluminium co ncentration in kidney was at and above 54 mu g/g wet tissue, kidney da mage was observed. The above results indicate that compromised kidney function including tubular damage induced by a low-dose-of CdMT may pl ay a crucial role in the accumulation of aluminium in brain and other tissues. Since tubular function decreases with age in human population s, these findings in rats may be of considerable importance if a simil ar phenomenon would occur in humans. Therefore, the possibility of inc reased aluminium retention in persons with low calcium and high alumin ium intakes may need to be further investigated.