In-vitro study on the effect of adenine nucleotides, heavy metals and ascorbic acid on the lysosomal enzymatic activity and release rotes in rat brain

ABSTRACT

The effects of multivalent cations such as Pb 2+, Zn 2+ and Fe 3+, adenosine triphosphate [ATP], adenosine diphosphate [ADP], and adenosine monophosphate [AMP] on the enzyme release and total activity from cerebral lysosomes isolated from adult albino rats were examined in vitro. The test compounds were used in two concentration levels of 10 -3 and 10 -5 M. The three selected marker lysosomal acid hydrolases are acid phosphatase [ACP], N-acetyl B-glucosaminidase [B-NAG], and N-acetyl galactosaminidase. The effect of ascorbic acid sole and combined with the multivalent cations in an equimolar concentration on these enzymes were also examined. The results of this study showed that, ascorbic acid and the cations inhibited the enzyme release by different susceptibility on the lysosomal membrane. The suppressive effect of cations was significantly affected by treatment of the lysosome with ascorbic acid. On the other h and, ATP and ADP resulted in a decrease of ACP and B-NAG, while there was no effect on N-acetyl galactosaminidase activity. The total enzymatic activity of ACP was more inhibited than B-NAG by 10 -5 M of adenine nucleotides, while N-acetyl galactosaminidase activity was not affected by these nucleotides. AMP has no effect on the enzyme release. In addition, the degree of inhibition on the enzyme activity and release rate was decreased in the presence of ascorbic acid. In some cases, the inhibitory effect of the cations was changed to increase in either total activity or enzyme release by ascorbic acid