Abstract
The movement of calcium ions in the smooth muscle of guinea-pig taenia coli under various conditions was estimated by means of radioisotope technique. Uptake of 45Ca was not affected by the temperature of the soaking Krebs solution, whereas the rate of efflux of 45Ca decreased considerably in low temperature Krebs solution. Ethylenediamine-tetraacetate (EDTA) increased not only the rate of loss of 45Ca but also influenced markedly the movements of sodium and potassium ions in this tissue; after 30 minutes' incubation in 4mM EDTA-Krebs solution, taenia coli lost about 60m-mole/kg wet wt. potassium and gained 55m-mole/kg wet wt. sodium. Depolarization by high potassium, application of adrenaline, histamine or scrotonin increased the efflux of calcium, but the effect of acetyl-choline was variable dependent on the state of muscle preparation.
