The effect of fasting and time of day on the urinary excretion of chondroitin 4/6 sulphate, dermatan sulphate and four chondroitinase ABC resistant glycosaminoglycans.

The present investigation confirmed a former report of a diurnal variation with an increased urinary excretion rate of total glycosaminoglycans in the daytime [4]. Fractionation showed that this increase was solely due to three electrophoretic fractions which resisted degradation with chondroitinase ABC. Fasting in the daytime had no influence on the increased excretion of one of these fractions, whereas it prevented the increased excretion of the other two (probably both heparan sulphates). The excretion rates of chondroitin 4/6 sulphate, dermatan sulphate and a fourth chondroitinase ABC resistant glycosaminoglycan (heparan sulphate) were uninfluenced by time of day and fasting. This was contrary to the excretion of hydroxyproline which decreased during the fasting period.