EFFECTS OF CALCIUM DEPLETION ON OXYGEN CONSUMPTION IN GUINEA PIG TAENIA COLI

In smooth muscle of guinea pig taenia coli, showing spontaneous activity, the curves of rhythmic changes in muscle tension appears parallel to the curves of changes in Po2 level in the medium (1-3). On the other hand, Saito et al. (3) reported that an application of high K (isotonically, 40 mM) caused an increase in oxygen consumption accompanying increase in tension change in taenia coli, and that this was in accordance with the concept (4, 5) that the K-induced tonic response resulted from a transmembrane transport of Ca that depended on the aerobic breakdown of carbohydrates. In the present paper, effects of Ca depletion on the oxygen consumption accompanying muscle tension change both spontaneous and that induced by high K were studied, and a dissociation of the changes in oxygen consumption and muscle tension change was attempted by substituting strontium (Sr) for Ca in the external medium. Some of the results have already been reported (6, 7).