STUDY OF AGING RAT TAIL COLLAGEN USING ATOMIC-FORCE MICROSCOPE

Collagen structure of young and old rats was examined by using atomic force microscope (AFM) images. Rat tail tendons of eight and twenty-fo ur month-old Wistar rats were digested enzymatically (pepsin), and all owed to refibrillate for 24 hours at 37 degrees C. The samples were ex amined using a Nanoscope III (Digital Instruments, Santa Barbara, CA, U.S.A.) with a J scanning head and a 200 mu m silicon nitride cantilev er. The study was performed in air and without filters. The AFM inspec tion of refibrillated collagen produced images showing long fibrils wi th relatively homogeneous heights and widths, characterized by clear b anding with a periodic interval (D band) of 67 nm. With respect to col lagen extracted from young rats, collagen extracted from old rats reve aled fibrils exhibiting the same band interval, but with lower widths and heights. Furthermore, the depth of gap between two overlaps showed a higher mean value in the aged vats. These data are consistent with biochemical reports of collagen modifications during aging; we suggest that post-synthetic reactions might be responsible for this as they i nterfere with the refibrillation process and also modify the three-dim ensional structure of fibrils.