Calcium and ATPase activity during hepatic intoxication with thioacetamide.

The effects of acute thioacetamide (TAA) intoxication on the calcium, magnesium, sodium and potassium content of liver and on its ATPase activities were studied in rats. Samples of liver were analyzed by atomic absorption spectrometry for their cationic content 6, 24 and 48 h after administration of TAA through a stomach tube. After sonification other samples were assayed for (Na+ + K+)-dependent, (Ca2+ + Mg2+)- and Ca2+-dependent ATPases. No apparent correlation has been found between the increased hepatic calcium after TAA treatment and the variations of ATPase activity. Both calcium movement and ATPase activity appear sex-determined. These results bring support to the hypothesis that an interaction between TAA or its metabolites with the cell membrane provokes an increased influx of extracellular calcium. The relationship between this calcium increase and the changes in ATPase activity with the events triggering the neoplastic transformation is discussed.