In vitro selective glycogen depletion of frog twitch and slow muscle fibres.

Glycogen as measured histochemically with periodic acid-Schiff (PAS) reaction was depleted in frog muscle fibres following electrical stimulation of the nerve. The types of the muscle fibres examined were identified in serial cryostat sections. We used appropriate stimulation regimes which provide a heavy work load only for twitch fibres (at low stimulation frequency) or selectively for slow fibres (contractures in response to high frequency stimulation or pharmacological agents). Twitch and slow fibres lost their glycogen depending on the work load.