Thyroid control of small intestinal oxygen consumption and the influence of sodium ions, oxyhen tension, glucose and anaesthesia.

1. Oxygen consumption of jejunum removed from either killed or anaesthetized euthytoid, hypothyroid and triiodothyronine (T3)-treated rats was measured polarographically in vitro. 2. Hypothyroidism induced by drinking 6-n-propyl-2-thiouracil depressed jejunal oxygen consumption. 3. Treatment of euthyroid rats with T3 stimulated jejunal oxygen consumption by 39% in the presence of 28 mM glucose and by 23% in its absence. 4. Sodium ions appear to play a major permissive role in the action of T3 on jejunal oxygen uptake. In the presence of sodium, T3 stimulated significantly the oxygen consumption by 23% while in the absence of sodium the stimulation was only 10% which was not significant. The sodium-sensitive oxygen uptake of the jejunum was expanded by 57% after T3 treatment.