UNCHANGED 5'-DEIODINATING ACTIVITY DURING THE INDUCTION OF A NONTHYROIDAL ILLNESS

We investigated the formation of a ''nonthyroidal illness'' (NTI) in p igs undergoing ventricular fibrillation (VF) and resuscitation. Seven minutes after VF twenty-one pigs received either Epinephrine (E: 45 mu g/kg B.W.; n = 7), Norepinephrine (NE: 45 mu g/kg B.W.; n = 7), or Va sopressin (VP: 0.8 U/kg B.W.; n = 7). We determined the serum concentr ations (sc) of total T-4 (TT4), FT4, total T-3 (TT3) and rT(3) 120 min before, during (t(o)), and 5, 15, 60 and 120 min after VF. At the end of the observation period we figured out the in-vitro T-3-generation (k(M), V-max), the in-vitro rT(3) generation, the in-vitro rT(3)-decom position (k(M), V-max) and the content of cytosolic sulfhydryls (total sulfhydryls, non-protein bound sulfhydryls) in liver and kidney speci men. Animals not undergoing VF served as controls (C) for parameters m easured in the intracellular compartment. TT4- and TT3-sc decreased to 3.3 + 0.6 mu g/dl (p < 0.05, vs. t) and 15.2 +/- 4.1 ng/dl (p < 0.05, vs t(o)), resp. FT4-se remained stable for five minutes (2.63 +/- 0.4 1 ng/dl) before declining to 1.8 +/- 0.39 ng/dl (p < 0.05, vs. t(o)). The rT(3)-sc raised finally to 46.9 +/- 7.3 ng/dl (p < 0.05, vs t(o)). Iodothyronine sc did not exhibit differences between E-, NE- and VP-t reatment. Neither in-vitro T-3-generation, nor in-vitro rT(3)-generati on, nor in-vitro rT(3)-decomposition nor intracellular sulfhydryl cont ent were affected by the events of VF and resuscitation as compared to the controls. We therefore conclude that i. A low T-3 high rT(3)-synd rome is developed 120 min after VF in pigs; ii. The 5'-deiodination in liver and kidney, which contributes by approximately 60 % to circulat ing T-3 in euthyroid healthy beings, does not account for the alterati ons of iodothyronine sc within this interval of time.