Catch, peak tension and atpase activity in glycerinated oyster adductor

Abstract

1. 1. The relationship between peak tension, tension remnant (catch) and ATPase activity of glycerinated muscle fibres (GMF) from translucent (OTAM) and white (OWAM) parts of Ostrea edulis adductor was examined. 2. 1. Decay of tension after previous contraction is a first-order reaction given by the equation: P= P 2 0 ƒ+P 0 .e −kt , where k is constant for any given P 0. 3. 2. There is no difference between Ca activation of OTAM- and OWAM-GMF. 4. 3. The peak tension increases linearly with ATPase activity; the relation between tension remnant and ATPase activity is hyperbolic. 5. 4. The ratio OWAM/OTAM of the tension remnant is about 2·7 at low equal ATPase activity. The ratio of tension OWAM/OTAM is 1 3 at a Ca 2+ concentration of 9·3 × 10 −6 M; the corresponding ratio of ATPase activity is, after correction for protein concentration, also 1 3 . 6. 5. The K m is 0·56 mM for homogenized OTAM-GMF and 0·10 mM for OWAM, while the V mx of OTAM is 53·9 and that of OWAM 5·4 μmole/mg per min. 7. 6. These results are discussed in relation to the capacity of OTAM- and OWAM-GMF to generate catch.