Sialic acid: effect of removal on calcium exchangeability of cultured heart cells.

Specific removal of sialic acid from cultured heart cells with purified neuraminidase increases cellular calcium exchangeability. Potassium exchange is unaffected or slightly decreased. Sialic acid removal also permits lanthanum, normally restricted to the cellular surface, to enter the cells and displace more than 80 percent of cellular calcium. The results indicate a specific role of cellular surface components in the control of calcium exchangeability in the heart.