Changes of Plasma Levels of TRH and Its Target Hormones by Two Hour Constant Intravenous Infusion of TRH Tartrate in Man

Autor: Noriyuki Nihei, Yoshiharu Murata, Tadashi Kamikawa, Yasushi Ikeda, Yoshikazu Suzuki, Noboru Yamazaki
Rok vydání: 1979
Předmět:
Zdroj: Folia Endocrinologica Japonica. 55:1089-1097
ISSN: 0029-0661
DOI: 10.1507/endocrine1927.55.9_1089
Popis: Constant iv infusion of TRH tartrate for 2 hours was administered to normal men in a dosage of 0.5 (n=4), 1.0 (n=2) and 2 (n=4) mg/120 minutes. Measurements at every 15 minutes were performed for plasma levels of TRH, TSH, Thyroxine (T4) and Triiodothyronine (T3) by radioimmunoassay. Plasma levels of TRH increased promptly and stayed at the same levels until the end of the infusion. The Mean Clearance Rate (MRC), Half-life and Volume of Distribution of TRH were respectively, 4.62 +/- 0.53 L/min. (M +/- SE), 17.8 +/- 3.8 minutes and 112 +/- 15 L in the 0.5 mg administered group and 6.38 +/- 2.50 L/min., 9.0 +/- 1.4 minutes and 82 +/- 30 L in the 2 mg administered group. Plasma levels of TRH increased in two phases, and increments of plasma TSH were dose dependable to the dosage of TRH. Plasma levels of T4 increased gradually in the course of TRH infusion and stayed at high levels even in the withdrawal phase of TRH. Plasma levels of T3 increased markedly during and after the TRH infusion in the 0.5 mg administered group, while increments of plasma T3 were minute in the 2 mg administered group. From the above data, it is suggested that the amount of TRH production in man, which is much more than has previously been reported, may indicate the existence of an extrahypothalamic synthesis of TRH in man.
Databáze: OpenAIRE