Oxygen consumption by the isolated smooth muscle of guinea-pig taenia coli.

1. An apparatus is described for simultaneous measurement of oxygen consumption and electrical and mechanical activity of isolated smooth muscle preparations.2. The mean oxygen uptake by the isolated taenia coli of the guinea-pig was 10-20 mul./g/min.3. In spontaneously active preparations, adrenaline (10(-8)-10(-7) g/ml.) caused, with the inhibition of electrical and mechanical activity, a reduction in oxygen uptake.4. After prolonged exposure to substrate free solution spontaneous activity ceased periodically. Adrenaline, when applied during a silent period, had no detectable effect on resting oxygen consumption, while readmission of substrate, either glucose or beta-hydroxybutyrate, increased oxygen uptake.5. Adrenaline did not modify the increased oxygen uptake during the initial recovery period when it was given simultaneously with the substrate. However, adrenaline shortened the time interval which elapsed from the addition of substrate until spontaneous activity was resumed, indicating an acceleration of the recovery process.