Evidence for the Maillard reaction in rat lung collagen and its relationship with solubility and age.

This study investigated age-related changes in collagen solubility and collagen-linked fluorescence, and their relationship with the Maillard reaction. As a result of the collagen purification of rat lung samples, we obtained two pools of collagen with different degrees of solubility. The relative distribution of collagen between these two fractions was time-dependent, and the proportion of the smaller and less soluble fraction increased with time (r = 0.73, P < 0.0001). In this fraction, the intensity of fluorescence at Exc 335 nm/Em 385 nm, and the total amount of pentosidine increased with age (r = 0.66, P < 0.002, and r = 0.69, P < 0.01, respectively). The mean values for fluorescence and pentosidine per milligram of collagen were, respectively, six and ten times greater in the less soluble fraction. In this fraction the pentosidine per milligram of collagen increased with age (r = 0.59, P < 0.03). Our results demonstrated the presence of pentosidine in rat lung collagen. Moreover, its accumulation in the less soluble fraction suggested a relationship between Maillard reaction products, physico-chemical changes in collagen solubility, and the ageing process in rat lungs.