CA-CD INTERACTION IN THE PRYMNESIOPHYTE CRICOSPHAERA-ELONGATA

Abstract. 45Ca and 109Cd uptake were followed in Criscosphaera elongata Prymnesiophyceae. In both cases, after a rapid increase for the first 5 min, the incorporation rate slowed during the hour of observation. Verapamil, a blocker of voltage‐dependent slow calcium channels, inhibited 45Ca uptake except during the first rapid phase when adsorption should predominate. Cadmium also decreased 45Ca labelling, suggesting that the two metals are antagonistic. However, verapamil was shown to augment 109Cd incorporation, contrary to what occurs in animals cells; this effect is detectable in continuous labelling as well as in pulse experiments. The data support the presence of calcium channels in the alga and suggest several processes in Cd accumulation: adsorption on peripheral envelopes and diffusion of uncharged Cd. Copyright © 1990, Wiley Blackwell. All rights reserved