Carbohydrate metabolism of the lens depending on age.

Interpretation of factor analysis of 18 metabolic parameters of the bovine lens leads to the determination of the following criteria of lens metabolism: Factor 1: Biologic aging of the lens 33.9%; Factor 2: Glycolysis regulation 17.7%; Factor 3: Topography of lens metabolism 8.7%; Factor 4: Regulation of fructose breakdown 7.9%; Factor 5: Substrate depot 6.6%; Factor 6: Kinases 6.3%. These results could partly be experimentally verified. This interpretation of factor analysis has been an attempt to fit biochemical processes to formal statistical parameters. There was no indication that any of the variables under investigation were indendently responsible for the age dependend changes. However, the set-up made evident that rather complex biochemical influences of different intensity bring about the observed aging phenomena. It may be assumed that on or the other of these variables acts as a "triggering mechanism". Age related disturbances in the biochemical balance may be initiated by the glycolysis regulation factor, the importance of which is expressed by its high portion of 17%. Here changes in the ratio of reduced and oxydized coenzymes may act as a "triggering mechanism" (26, 30). Topography of lens metabolism, carbohydrate breakdown via metabolic pathways, the presence of substrate depots, and the internal regulation of the kinases are, according to their portion in factor loading, of about equal importance with respect to aging processes, however, factors 1 and 2, with a 50% portion, must be given precedence in any consideration. Factor 1, interpreted as "biological lens aging", yields about 1/3 of the information on the age influence on lens metabolism. This factor stands independent in being loaded by lens weight, which is the accepted age representative. However, lens weight means protein as well as the process of protein synthesis. It may be assumed that this factor represents a connective link between protein and carbohydrate metabolism, since it is well known that changes in protein belong to the most remarkable age disturbances (31,32), and that the quality of the proteins is dependent on the period of its synthesis (18,33).