Abstract
The changes of enzyme activities in subcellular fractions of rat liver were investigated after a single oral administration of zinc sulfate (20 mg Zn/100 g body weight). Zinc contents in the fractions of plasma membrane, nuclei, mitochondria, microsomes and cytosol were significantly increased 3 h after zinc administration. On the other hand, a significant decrease of the microsomal glucose-6-phosphatase activity and a remarkable elevation of the mitochondrial succinate dehydrogenase activity were caused by zinc administration, while the activities of the plasma membrane Ca2+-adenosine triphosphatase (ATPase), nuclear ribonucleic acid (RNA) polymerase and cytosolic acid phosphatase were not significantly altered. At the lowest dose (5 mg Zn/100 g) used in this experiment, the microsomal glucose-6-phosphatase activity was not significantly decreased, while the mitochondrial succinate dehydrogenase activity was markedly increased. Also, activation of succinate dehydrogenase in the liver mitochondria was observed at 12 h after zinc administration (10 mg Zn/100 g). The present study indicates that zinc taken up by the liver cells accumulates in the mitochondria and the metal may have an effect on the mitochondrial functions.
