CHANGES IN TITIN AND NEBULIN IN POSTMORTEM BOVINE MUSCLE REVEALED BY GEL-ELECTROPHORESIS, WESTERN BLOTTING AND IMMUNOFLUORESCENCE MICROSCOPY

Postmortem storage of bovine psoas major muscle resulted in almost complete degradation of nebulin by 48 hr; however, some intact titin was still observed after 2 wk storage at 4-degrees-C. The percentage of myofibrils having four anti-titin bands per sarcomere (immunofluorescence microscopy) was less than 1% at 45 min but increased to 65% at 48 hr after death and remained stable thereafter. A similar four band pattern was seen in frozen sections of whole muscle at 48 hr or more postmortem. The time course of nebulin degradation appeared to correlate with the titin two to four band transition.