THE RESPONSE OF THE PLASMA PROTEIN-BOUND IODINE OF HYPOPHYSECTOMIZED DOGS TO INJECTED THYROTROPIN: THE INFLUENCE OF CORTISONE

Abstract

Thyroid function was studied in dogs by means of plasma protein-bound I detns. Plasma protein-bound I concn. of normal dogs was 2.6 [mu]g.% [plus or minus] 1.18 [mu]g.% (S.D.). Following hypo-physectomy, protein-bound I fell to low levels (1.0 [mu]g.%) by the 5h postoperative day. Single injns. of 10 mg. of thyrotropin in hypophysectomized dogs resulted in an increase in plasma protein-bound I concn. Detectable elevation was observed at the 4th hour after injn. Max. concns. were reached by 24-30 hours, after which a decline to preinjection low levels occurred. Repeated injns. of thyrotropin resulted in an initial elevation of plasma protein-bound I, followed by a decline after 2-5 days while injns. of the same dosage at the same frequency were being continued. Concurrent admn. of cortisone did not alter the magnitude or duration of the response of the plasma protein-bound I due to single or multiple injns. of thyrotropin, and did not influence rate of disappearance of protein-bound I from plasma following max. elevation after a single injn. of thyrotropin in hypophysectomized dogs.