A comparative study of the subcellular binding of phenylmercuric acetate and mercuric acetate in rat liver and kidney slices

Abstract

Studies were made to determine the extent of uptake and the rate of binding of 203Hg-labeled phenylmercuric acetate (PMA) and mercuric acetate (Hg ++) in rat kidney and liver slices at 37° and their distribution in subcellular fractions, after incubation in Krebs-Ringer phosphate solutions containing 10 −4 M mercurials. The time course of uptake showed that the rat kidney slices rapidly took up both PMA and mercuric ion at the same rate while liver slices incorporated the two mercurials at a much slower rate, with PMA at about twice the rate of mercuric ion. In the study of mercury distribution in subcellular fractions the percentages of PMA or Hg ++ bound to mitochondrial and microsomal fractions were low and remained almost constant during a 3-hour experimental period. The bindings of 203Hg from PMA or Hg ++ into the nuclear fraction were high and tended to increase as the time of incubation increased, while the 203Hg in the soluble fraction was decreased with the time of incubation. When a comparison was made on the specific binding of mercurials, it revealed that the binding of PMA into mitochondrial, microsomal, and soluble fractions was generally 1.5 to 2 times greater than those of mercuric ion. Only in the nuclear fraction of kidney a greater binding of mercuric ion was noted. This difference in intracellular distribution may be responsible for the different toxicity of PMA and mercuric ion in biological systems.