Postmortem proteolysis and calpain/calpastatin activity in callipyge and normal lamb biceps femoris during extended postmortem storage

The present experiment was conducted to determine whether calpastatin inhib its only the rate, or both the rate and extent, of calpain-induced postmort em proteolysis. Biceps femoris from normal (n = 6) and callipyge (n = 6) la mb was stored for 56 d at 4 degrees C. Calpastatin activity was higher (P < .05) in the callipyge muscle at 0 and 14 d postmortem, but not at 56 d post mortem. The activity of mu-calpain did not differ between normal and callip yge biceps femoris at 0 and 56 d postmortem(P >.05), but was higher at 14 d postmortem in the callipyge muscle (P <0.05). The activity of m-calpain wa s higher in the callipyge muscle (P <0.05). Western blot analyses of titin, nebulin, dystrophin, myosin heavy chain, vinculin, alpha-actinin, desmin, and troponin-T indicated that postmortem proteolysis was less extensive in callipyge than in normal biceps femoris at all postmortem times. The result s of this experiment indicate that calpastatin inhibits both the rate and e xtent of postmortem proteolysis.