Somatomedin Activity From Rat Livers Perfused With Human Growth Hormone

Department of Growth and Development, Institute of Child Health, 30 Guilford Street, London, WC1N 1EH (Received 17 June 1974) Although somatomedin (SM) is established as the hormone through which growth hormone (GH) affects bone growth (Daughaday, 1971), the organ that produces it is not yet known (Van Wyk, Underwood, Lister & Marshall, 1973). McConaghey & Sledge (1970) showed that the addition of bovine GH to perfusion fluids passing through the liver led to an increase of sulphation factor (incorporation of thymidine was not examined) but this was measured only with a 2-point assay. Hintz, Clemmons & Van Wyk (1972) produced apparent sulphation factor activity by superfusion of liver slices with media containing human GH but the dose–response curves were not parallel to those produced by plasma. SM activity has been reported from perfused kidneys (McConaghey & Dehnel, 1972) and from muscle (Hall, Holmgren & Lindahl, 1970). Rats were perfused using