AJP - Renal Physiology, Vol 251, Issue 5 784-F794, Copyright © 1986 by American Physiological Society
Renal handling of cadmium in perfused rat kidney and effects on renal function and tissue composition
G. L. Diamond, J. J. Cohen and S. L. Weinstein
Isolated rat kidneys perfused with a Krebs-Ringer bicarbonate (KRB)
solution containing 1 microM CdCl2 plus 6% substrate-free albumin (SFA) and
a mixture of substrates accumulated substantially less cadmium in tissue
than kidneys perfused with 1 microM CdCl2 in a protein-free KRB solution
containing the same substrates: 11 vs. 205 nmol Cd/g dry wt. Decreasing the
glomerular filtration rate (GFR) by occluding the ureters of kidneys
perfused in the absence of albumin did not change the rate of net tissue
uptake of cadmium (Cd), suggesting that the kidney can extract Cd from the
peritubular capillary fluid and that net uptake of Cd is not dependent on
the reabsorption of filtered Cd. The tissue accumulation of large
quantities of Cd (1.8 mumol Cd/g dry wt), which established levels of
non-metallothionein-bound Cd exceeding 1 mumol Cd/g dry wt, caused no
changes in either GFR, perfusion flow rate, fractional reabsorption of Na+,
fractional reabsorption of K+, fractional reabsorption of glucose, or
free-water clearance. However, discrete changes in renal tissue K+ content
were observed. Exposure to 1 microM CdCl2 resulted in a net loss of renal
tissue K+ in rat kidneys perfused with substrate-enriched KRB containing 6%
albumin. Exposure to 0.8 microM or 7 microM CdCl2 completely prevented K+
loss from kidneys perfused with a substrate-enriched, protein-free KRB
solution.
