RESUMEN
The incorporation of [35S]-SO4 into glycosaminoglycans of liver in vivo and in in liver slices and into the glycosaminoglycans associated with the hepatic plasma membrane of rats at different periods after a heavy dose of CC14 have been studied. The incorporation of [35S]-SO4 into total glycosaminoglycans decreased to as low as 40% of the control at 24 h after the administration of CC14 and later on increased reaching a maximum on the 4th day. The amount of [35S]-SO4 incorporation into heparan sulphate was also reduced to about 40% of control at 12–24 h after the onset of injury and increased thereafter reaching a maximum on the 4th day. There was only a partial reduction in the synthesis of chondroitin sulphate in the early stage of injury and then it steadily increased reaching about 3 times the control level on 4-6 days. The [35S]-SO4-incorporation into dermatan sulphate, after a slight initial decrease remained at the control levels. On the 8th day after the CCl4-induced liver injury, the rate of [35S]-SO4-incorporation was almost equal to that in normal controls. The incorporation of [35S]-SO4 into hepatic plasma membrane glycosaminoglycans showed a similar change decreasing to about 35% of control at 24h followed by an increase, reaching normal levels on the 4th day after the administration of CC14. About 90% of the plasma membrane glycosaminoglycans was found to be heparan sulphate. The yield of plasma membrane from normal and CCl4-induced regenerating liver was found to be similar and therefore the results obtained were not due to difference in the yield of the membrane preparation. The data also indicate that there was no difference in the degree of sulphation. The significance of these changes in the metabolism of sulphated glycosaminoglycans particularly plasma membrane heparan sulphate in tissue regeneration has been discussed.
RESUMEN
Magnesium deficiency in rats has significant effect on the concentration of different glycosaminoglycans in the tissues, the nature of the change being different in different tissues. Total glycosaminoglycans, chondroitin-4-sulphate + chondroitin-6- sulphate and dermatan sulphate increased in the aorta while hyaluronic acid, heparan sulphate and heparin decreased. In the liver, total glycosaminoglycans, hyaluronic acid, chondroitin-4-sulphate + 6-sulphate and heparin decreased while total glycosaminoglycans and all the glycosaminoglycan fractions increased in the heart. In the kidney, total glycosaminoglycans showed no significant alteration, hyaluronic acid and heparin decreased while chondroitin-4-sulphate + 6-sulphate increased. Activity of biosynthetic enzymes viz. glucosamine-o-phosphate isomerase and UDPG-dehydrogenase showed decrease in the liver. The concentration of 3'-phosphoadenosine 5'-phosphosulphate, activity of sulphate activating system and sulphotransferase were also similarly altered in the liver in magnesium deficiency.