Abstract

We examined the detraining effects on the exercise-induced changes of the distensibility and elastic components of the rat aorta. Exercised (E) and sedentary (S) rats were divided into two groups respectively (i.e., E1, E2, S1, and S2). The E1 and E2 ran in a wheel cage spontaneously for 16 weeks from 9 to 25 weeks old. The E1 and S1 were sacrifi ced at the end of the exercise period. The E2 and S2 were bred sedentarily for 15 weeks until 40 weeks old. The aortic incremental elastic modulus at extension ratio of 1.5 and the contents of polar amino acids and calcium in aortic elastin were signifi cantly lower in E1 than in S1. The aortic incremental elastic modulus and polar amino acids content were increased with aging signifi cantly in S2 but not signifi cantly in E2, and accordingly, those values were signifi cantly lower in E2 than in S2. The content of elastin calcium, however, was increased significantly not only in S2 but also E2. The increase was especially marked in E2, and then, there was no significant difference in the values between two groups. These results suggest that the aortic wall in exercise-trained rats may keep more distensible structure with lower elastic fiber degeneration for a long time compared with sedentary rats even after detraining. The reason why elastin calcium content in the exercise-trained rats was markedly increased after the detraining was remain to be investigated. Verf.-Referat