Changes with age in the metabolism of sulfated glycosaminoglycans in guinea pig cardiac valves

Abstract

1. 1|The formation and turn-over of sulfated glycosaminoglycans of the ground substance of cardiac valves was studied by autoradiography following the administration of S 33-sulfate in vivo to guinea pigs 10 days to 5 years of age. The experiments comprised a qualitative study involving all four heart valves in a group of 3-week-old animals, and a quantitative study on the aortic valve by age groups. The latter study included the use of testicular hyaluronidase for differentiation between chondroitin sulfates and dermatan sulfate. Sections from all the animals were examined for alterations with age in structural appearance and occurrence of metachromasia. 2. 2.|Moderate differences in structure and in amount and distribution of metachromasia were noted between growing and mature animals. There was no evidence, in 3- and 5-year-old guinea pigs, for degeneration with age such as has been observed in humans. 3. 3.|In the qualitative study, the cardiac valves showed a prominent incorporation of S 35, which equaled that of cartilage occurring in the aortic wall, trachea and bronchi. However, the turnover was more rapid in the valves than in cartilage. There was no significant difference between the four valves with regard to level of uptake, or turnover. 4. 4.|The metabolism of sulfated glycosaminoglycans is slowed with age, both in the rate of synthesis and in turnover time. 5. 5.|Digestion with testicular hyaluronidase indicated an increase with age in the proportion of dermatan sulfate in the ground substance.