A quantitative cytochemical method for estimating alkaline phosphatase activity

Publisher Website
Google Scholar
Abstract
By the use of interference microscopy the rate of deposition of calcium phosphate, resulting from enzyme activity, can be measured quantitatively. This provides a quantitative measure of enzyme activity at individual cellular sites. By this method, studies have been made of the effect of variation in substrate concentration, pH, temperature and calcium-ion concentration on the enzymatic activity of the brush border regions of rat-kidney tubules and of duodenal epithelium. Some observations of cell nuclei have also been made. Under standard conditions of incubation (Danielli 1953) at least 97⋅5% of the phosphate ions liberated in a kidney section are precipitated, and once precipitated the calcium phosphate does not redissolve. Under standard conditions of incubation no loss of enzyme activity from brush borders of kidney and duodenum could be detected.