BIOASSAY OF GROWTH HORMONE AND PROLACTIN PREPARATIONS BY DETERMINATION OF LONGITUDINAL BONE GROWTH WITH TETRACYCLINE

Abstract

The growth stimulating effect of different growth hormone and prolactin preparations on the longitudinal bone growth in thyroxine-treated hypophysectomized rats was determined by the tetracycline method. The effect of the hormone preparations was compared with that of the 1st International Standard for growth hormone. The potency calculation showed that the tested human growth hormone preparations have a higher potency than the bovine, ovine and porcine growth hormone preparations. Also potency differences were found between hormones from the same species but prepared by different methods. The prolactin preparations have a considerably lower growth promoting activity than the growth hormone preparations. The bioassay method used in the present investigation has a favourable mean precision (λ = 0.172) and sensitivity compared with the earlier bioassay methods. The present method increases the possibility of determining the biological effects of various growth promoting substances.