Renal Handling of Sodium and Potassium in Cadmium Exposed Rats

Renal Handling of Sodium and Potassium in Cadmium Exposed Rats

<P> Effects of cadmium exposure on renal Na<SUP>&#8290;</SUP> and K<SUP>&#8290;</SUP> transports were studied in rats. During the course of cadmium treatment (2 mg Cd/kg/day, s.c. injections for 3 weeks) renal tubular transports of Na<SUP>&#8290;</SUP> and K<SUP>&#8290;</SUP> were evaluated by lithium clearance technique. During the early phase (first week) of cadmium treatment, urinary Na<SUP>&#8290;</SUP> excretion decreased drastically and this was due to an increased Na<SUP>&#8290;</SUP> reabsorption both in the proximal and distal nephrons. During the late phase (third week) of cadmium treatment, filtered Na<SUP>&#8290;</SUP> load was decreased by reduction in GFR, but the renal Na<SUP>&#8290;</SUP> excretion returned to the control level due to impaired Na<SUP>&#8290;</SUP> transport in the proximal tubule. Urinary excretion of K<SUP>&#8290;</SUP> did not change during the early phase, but it rose markedly during the late phase of cadmium treatment. These results indicate that a light cadmium intoxication induces a Na<SUP>&#8290;</SUP> retention, and a heavy intoxication results in a K<SUP>&#8290;</SUP> loss. Possible mechanisms for these changes are discussed.