Effect of age, sex, starvation, hypophysectomy and growth hormone from several species on the inorganic sulphate pool and on the incorporation in vivo of sulphate into mouse costal cartilage. An attempt to study sulphation factor activity in vivo.

Abstract

ABSTRACT The influence of several conditions on sulphate incorporation into costal cartilage was investigated in mice of the N.M.R.I.-strain and in dwarfmice (dw/dw) by a new double isotope technique. The method permits estimation of sulphate incorporation into costal cartilage in vivo after correction for the size of the exchangeable inorganic sulphate pool of the individual animal. Detoxication to phenyl sulphate of injected phenol, following an injection of 3H-phenol and 35S-sulphate into the mice, allows determination of the sulphate pool. The incorporation rate of sulphate is expressed in ng, and includes all SO4 which had been incorporated in vivo into 5 pairs of cartilaginous ribs including their osteochondral junctions during 30 minutes. Sulphation rate was rather constant in growing female mice between 3 and 8 weeks age and then decreased markedly. Growing male mice exhibited an increase of sulphation activity until an age of 5 weeks and then a gradual decrease, similar to that of the females. Growth rates of both sexes were positively correlated with sulphate uptake activities. The form of the disappearance curve of incorporated sulphate suggested that the standard cartilage sample includes regions with different sulphate-metabolizing activities. Hypophysectomy resulted in a decrease of sulphation rate to a level about 30% of the control values, which was constant for several weeks. Starvation of the animals likewise depressed the sulphation rate and after 72 hours starvation the values became similar to those after hypophysectomy. Dwarf mice had much lower sulphation activities than their heterozygous controls. Neither bovine GH nor human GH elevated the low sulphation activity of hypophysectomized mice but porcine and ovine GH-preparations had a pronounced and dose-dependent effect. Normal growing male and female mice showed no response to large doses of ovine GH. Ear, xiphoid and tracheal cartilage from hypophysectomized animals behaved as costal cartilage with respect to the reduction in sulphation rate, but GH restored the sulphation values to normal only in costal cartilage. A single dose of 1 mg ovine GH given to hypophysectomized mice at different times in relation to the sulphation experiment increased sulphate incorporation only after a time lag of more than 8 but less than 17 hours after injection of GH, whose effect lasted at least 38 hours.