Atrial natriuretic hormone, vessel dilator, long-acting natriuretic hormone, and kaliuretic hormone decrease the circulating concentrations of total and free T-4 and free T-3 with reciprocal increase in TSH

The present investigation was designed to determine whether atrial natriure tic peptides (ANPs) consisting of amino acids 1-30 [i.e. long-acting natriu retic hormone (LANH)], 31-67 (vessel dilator), 79-98 (kaliuretic hormone), and 99-126 (atrial natriuretic hormone [ANH]) of the 126-amino acid ANH pro hormone decrease the circulating concentrations of total and free T-4 and/o r free T-3 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 Ts decreased 72%,67%,71%, and 67% (P < 0.05 for each), respectively, when inf used at 100 ng/kg BW-min for 60 min. Vessel dilator, kaliuretic hormone, LA NH, and ANH simultaneously increased circulating TSH concentrations 4- to 1 2.5-fold (P < 0.004). The decreases in T-4 and T-3 with reciprocal increase s in TSH lasted 2-3 h after cessation of the respective ANP infusions. The reciprocal increase in TSH with the decreases in T-4 and T-3 suggests that their modulation of T-4 and T-3 concentrations occurs in the thyroid rather than in the pituitary or hypothalamus, because TSH would be decreased in t he circulation if their inhibitory effects were in either the hypothalamus or pituitary.