Acid-proteinase activity of rat cartilage dependent on growth hormone

Cartilage slices from normal rats, incubated at pH 4 for 3 to 7 hours, on a gelatin-membrane substrate, digested the membrane, whereas cartilage from rats hypophysectomized for 21 days or more did not. Injection of 15 or 45 microgram of bovine growth hormone into hypophysectomized rats restored the lytic activity of the cartilage. It is concluded that an acid proteinase is present in cartilage of normal rats, that is lost after hypophysectomy, and that the enzyme is restored by injection of growth hormone.