Cellular heterogeneity in the response of beef to electrical stimulation

Strips of bovine sternomandibularis muscle were removed at slaughter and kept anoxic at body temperature. One strip of each pair was electrically stimulated with square wave pulses for 60 min (32 ms duration, 2Hz, <6 or 100V). Differences between stimulated and control strips were examined histochemically to determine the effect of stimulation on post-mortem glycogenolysis in different fibre types. Serial reactions for ATPase and SDH were used to type muscle fibres and the absorbance of PAS-stained glycogen was measured with a two-wavelength correction for distributional error. Relative to unstimulated control strips, fibres with strong ATPase and weak SDH reactions showed most glycogenolysis whilst fibres with weak ATPase and strong SDH reactions showed the least. Fibres with strong ATPase and strong to moderate SDH reactions showed an intermediate response. Half of the fibre populations examined had an initial increase in absorbance of PAS-stained glycogen in some or all fibres.