Calcium Movement in the Smooth Muscle of Guinea-pig Taenia Coli

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Abstract
The movement of calcium ions in the smooth muscle of guinea-pig taenia-coli under various conditions was estimated by means of radio-isotope technique. Uptake of Ca45 was not affected by the temperature of the soaking Krebs solution, whereas the rate of efflux of Ca45 decreased considerably in low temperature Krebs solution. Ethylenedi-amine-tetraacetate (EDTA) increased not only the rate of loss of Ca45 but also influenced markedly the movements of sodium and potassium ions in this tissue; after 30 minutes'' incubation in 4 m[image] EDTA-Krebs solution, taenia-coli lost about 60 m-mole/kg wet wt. potassium and gained 55 m-mole/kg wet wt. sodium. Depolarization by high potassium, application of adrenaline, histamine or serotonin increased the efflux of calcium, but the effect of acetylcholine was variable dependent on the state of muscle preparation.