Serum enzymes are derived from large organ such as liver, kidney, heart and skeletal muscles. A standardization of assay methods for serum enzymes is available not only to diagnose correctly the diseases of these organs, but also to compare with the data from each laboratory.
But a method to an enzyme is not suitable for enzymes with isozymes. Each isozyme has its own condition in preservation and assay. The Km and Vmax is also proper to each isozyme. So the datum from one method must lead to suggest the disturbance of some organs, and to deny the disturbance of the others.
By using these difference in nature between isozymes, on the contrary, the source of serum enzyme can be searched after. In our labolatory the quantity and quality of serum enzymes have been studied in connection with the pathogenesis of muscular dystrophy1-6). This has necessarily led us to find the findings as follows. Serum LDH isozyme of Ducheme type changes with age, as a result of the progression of the disease. At an early stage its serum enzymes are derived mainly from white muscles. At the final stage these are derived mainly from red or heart muscles. For these studies only an assay method to LDH was not suitable.
In addition to muscular dystrophy mentioned above, recent reports indicate that increases of serum activities of CPK can also occur in some patients with such neurologic and psychiatric disorders as cerebral vascular disease and acute psychosis, and also that in these cases the composition of CPK is not BB type but MM type7). So some studies were made to elucidate by what mechanism a leakage of muscle enzyme into the serum occurs.
Using male rabbit 3 kg weighing, medial (sympathetic) or lateral (parasympathetic) area was electrically stimulated for 30 minutes. After a stimulation of sympathetic area, but not of parasympathetic area, serum enzyme activities of muscle type increased significantly in sera with a maximum at 6 to 18 hrs. Stimulation on sympathetic hypothalamus released such soluble sarcoplasmic enzymes as CPK, aldolase and LDH from white muscle to sera. These findings indicate more that individuals must be conditioned prior to sampling for LDH, CPK and aldolase assay, and also that the studies on pathogenesis of the above mentioned diseases go forward.
