EFFECTS OF TAURODEOXYCHOLATE AND CALCIUM ON CONTRACTILITY OF NEWT EGGS

Injection of taurodeoxycholate (TDOC) alone or in combination with 10-5 M Ca2+ (Ca-EGTA buffer) into newt eggs induced a cup- or furrow-like depression on the egg surface. Reduction of the Ca2+ concentration inhibited the response. These findings imply that TDOC induces a cytoplasmic contraction associated with the membrane and that a micromolar Ca2+ concentration is required for this process. Injection of 10-5 M Ca2+ (Ca-EGTA buffer) alone had no effect. On the basis of these findings, the roles of TDOC and Ca2+ in induction of contraction were discussed.