Variations in [3H]ouabain binding of porcine skeletal muscle associated with feeding

The maximal ouabain binding capacity (Bmax) of longissimus dorsi muscle has been determined over a 24 h period in young pigs living at 12 degrees C. Animals were fed once a day and Bmax was estimated at 4, 8, 12 or 24 h after a large meal. Mean values of Bmax +/‐ S.E.M. (pmol ouabain/g wet wt muscle) of 548 +/‐ 78 and 556 +/‐ 57 at 4 and 24 h after feeding were significantly greater than those of 383 +/‐ 24 and 393 +/‐ 30 at 8 and 12 h after feeding (P less than 0.02). The extent to which these differences represent apparent or real changes in numbers of ouabain binding sites and, hence, in Na+,K(+)‐ATPase concentration is discussed.