Calcium Exchange in a Single Layer of Rat Cardiac Cells Studied by Direct Counting of Cellular Activity of Labeled Calcium

Calcium exchange was studied in rat cardiac cells grown in tissue culture. A new technique was employed which depended on the growth of a single layer of cells on the surface of a slide composed of glass scintillator material. The cells remained actively contractile on the glass surface. The pattern of 45 Ca uptake and washout from the preparation was defined and found to be reproducible. Low Na + perfusion rapidly augmented 45 Ca uptake in the cultured cells. An increment in 45 Ca uptake (65 µmoles Ca 2+ /kg cells) occurred within 6 seconds of the start of low Na + perfusion.