Quantitative analysis of tenascin in chordae tendineae of human left ventricular papillary muscle with aging

A computer image analysis was done to investigate the distribution of tenascin and collagenous matrix components (collagen types I and III) in the chordae tendineae of the anterior cusp of the left ventricular papillary muscle, using confocal laser scanning microscopy in both a 20s age group and an 80s-90s age group. Tenascin and the collagenous matrix components showed marked accumulation in the 80s-90s age group with elastic fiber concentration being increased in the same region as that in the 20s age group. The highest content of intersurface layer staining with an anti-tenascin antibody and with anti-collagen type III in the inner layer was found in the 80s-90s age group. These content levels were low in each region in the 20s age group. The distribution and content of these extracellular matrix changes are related to the changes in mechanical performance of the cardiac muscle with age.