Abstract
Summary
L-3,3′,5-Triiodothyronine (T 3) potentiated epinephrine-induced contractions of isolated rabbit aortic strip only under the following conditions: 1) copper acetate (2 × 10-7) addition to the bath or 2) when trace metal contaminants were occasionally present in the bath, as suggested by short duration control responses to epinephrine. EDTA, a potent chelating agent, similarly potentiated epinephrine contractions. It was further demonstrated that T 3 delays metal-catalyzed oxidation of epinephrine in separate incubate experiments. This effect appears to be the major factor in potentiation of epinephrine contractions by T 3. It is further concluded that T 3 probably acts by virtue of its metal-chelating effect.
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