Atrial Natriuretic Hormone, Vessel Dilator, Long-Acting Natriuretic Hormone, and Kaliuretic Hormone Decrease the Circulating Concentrations of Total and Free T4 and Free T3 with Reciprocal Increase in TSH

Abstract

The present investigation was designed to determine whether atrial natriuretic peptides (ANPs) consisting of amino acids 1–30[ i.e. long-acting natriuretic hormone (LANH)], 31–67 (vessel dilator), 79–98 (kaliuretic hormone), and 99–126 (atrial natriuretic hormone [ANH]) of the 126-amino acid ANH prohormone decrease the circulating concentrations of total and free T4 and/or free T3 in healthy humans (n = 30). Vessel dilator, kaliuretic hormone, LANH, and ANH decreased the circulating concentrations of total T4 by 61%, 58%, 47%, and 55% and of free T4 by 60%, 67%, 79%, and 79%, whereas free T3 decreased 72%, 67%, 71%, and 67% (P < 0.05 for each), respectively, when infused at 100 ng/kg BW·min for 60 min. Vessel dilator, kaliuretic hormone, LANH, and ANH simultaneously increased circulating TSH concentrations 4- to 12.5-fold (P < 0.004). The decreases in T4 and T3 with reciprocal increases in TSH lasted 2–3 h after cessation of the respective ANP infusions. The reciprocal increase in TSH with the decreases in T4 and T3 suggests that their modulation of T4 and T3 concentrations occurs in the thyroid rather than in the pituitary or hypothalamus, because TSH would be decreased in the circulation if their inhibitory effects were in either the hypothalamus or pituitary.