Biochemical studies on human salivary proteins. XI. Effect of saliva-parotin-A on phosphatase activities

Abstract

The effect of saliva-parotin-A (SPA) on the serum and prostatic phosphatase activities was investigated in intact and parotidectomized rabbits. The enzyme activities were measured with p-nitrophenylphosphate as substrate for serum phosphatases and with β-glycerophosphate for prostatic acid phosphatase. A single injection of 100 μg/kg of SPA decreased significantly the serum acid phosphatase activity after 5.5 hr, but had no effect on the serum alkaline phosphatase activity. The prostatic acid phosphatase activity towards β-glycerophosphate decreased slightly, but the decrease was not statistically significant against the control due to deviation of the measured values. No difference was found in the serum acid and alkaline phosphatase activities between intact and parotidectomized rabbits. The serum acid phosphatase activity in immature rabbits was higher than that in adults and became lower as the body weight increased. A marked decrease in the serum acid phosphatase activity was observed when SPA was given to parotidectomized immature rabbits. These results suggest that the depression of the serum acid phosphatase activity by SPA may be attributed to the decrease in the release of the enzyme from bone cells, and/or that SPA may affect indirectly the acid phosphatase activity level in serum, into which the enzyme is released from leukocyte cells.