The mechanism of cell fusion. I. Energy requirements for virus-induced fusion of Ehrlich ascites tumor cells.

Fusion of Ehrlich ascites tumor cells was carried out in an isotonic salt solution at pH 7.8. Fusion occurred efficidntly even under nitrogen with glucose as the only added substrate. In the presence of NaCN (1 mu), rotenone (0.5 mM), or dinitrophenol (0.25 mM) the process was absolutely dependent on glucose concentration (1 to 10 mu). Inosine alone (10 mM) or with addition of adenine (2 m&r) could replace glucose when fusion was carried out in the presence of NaCN. High concentration of Ca++ (20 mu) or Mnf+ (6 mM) facilitated fusion even in the absence of glucose. In the presence of ouabain (0.1 mM), Ca++ is not required for fusion. Ca++ was also not required in a medium of high KC1 and low NaCl which, like ouabain, is known to inhibit sodium and potassium ion-stimulated adenosine triphosphatase. The data presented strongly suggest that all possible conditions which allow agglutination to occur and suppress virusinduced lysis might be sufficient for the fusion process.