[The determination of the glycogen phosphorylase activity in blood serum]

A method for measuring blood serum glycogen phosphorylase (GP) activity is described, informative at early stages of myocardial infarction. The method is sensitive and available for clinical biochemistry laboratories. It consists in preliminary purification of GP from serum proteins and metabolites by affinity chromatography in micro-columns and subsequent measurement of the activity in the eluate. The procedure involves selective GP sorption on starch, washing, and subsequent desorption with glycogen solution. GP activity is measured by the kinetic spectrophotometric technique, based on enzymic measurement of glucose-1-phosphate, the product of glycogen consumption reaction, at a wavelength of 340 nm. Conditions of serum GP chromatographic purification are modified in the suggested procedure, this improving the sensitivity of the enzyme measurement. Blood serum GP activities were measured in patients with various cardiac diseases--myocardial infarction (15 cases), angina of rest and effort (53), essential hypertension (30). Different methods of GP activity measurements are considered. Recommendations on the use of the described method, a sensitive test for the diagnosis of myocardial infarction, are given.