Effect of aging on human aortic protein composition. I. One-dimensional polyacrylamide gel electrophoretic analysis of tissue extracts.

Proteins extracted from matching areas of homogenized intimas of 17 human aortas, from two age groups (15-34 and 35-82), were studied after separation by polyacrylamide gel electrophoresis, silver staining, and densitometric scanning. Several definite protein bands including 6 major and 16 minor bands were identified in 17 aortic intima samples grossly and microscopically lesion free. However, such electrophoretic patterns were found to differ in the two age groups studied. For instance, (1) the integrated densities (amounts) of protein bands 1, 6, 13, 16, and 19 which we interpreted as of mural vascular origin were significantly higher in the younger age group, whereas the amounts of bands 2, 7, 9, 11, and 21 suspected to be of plasma origin were found to be significantly higher in the older age group; (2) protein band No. 8 was found to be double in the younger age group vs a single line in the older age group, whereas band No. 12 was the opposite. These changes in protein composition appear to correlate closely with diffuse intimal thickening found histologically in older age group, and will be further studied to relate to those in atherosclerotic lesions.