The effect of hypophysectomy and adrenocorticotropic hormone on the alkaline phosphatase of rat plasma.

It is well known that the phosphatase content of bone, kidney, liver, and blood may change under varying conditions of growth, diet, and disease (1). Among these tissues, blood perhaps furnishes the over-all changes of this enzyme activity. Weil (2) found a rise in plasma phosphatase activity from birth to maturity during the growth of normal rats. Kinard and Chanutin (3) have reported that the phosphatase content of the whole rat increases from the time of birth. There is ample evidence that certain bone diseases cause a marked alteration in plasma phosphatase (4). Furthermore, phosphatase has been shown to play a part in bone regeneration (5). The effects of hypophysectomy on bone histology have been described recently by Becks, Simpson, and Evans (6). The immediate reaction is a thinning of the cartilage plate, and after longer postoperative intervals the bony trabeculae become coarser and less numerous. Since the phosphatase activity is intimately related to changes in bone, one may expect that changes may occur in plasma phosphatase after hypophysectomy. In a survey of the literature, there appears only one report (7) on serum phosphatase activity in hypophysectomized rats.