Fig. 2. Force generation measured with a strain gauge in response to depolarisation produced by an elevation of external K⁺ concentration to 100 mmol l^-1 in red skeletal muscle fibres. The red muscle fibre tissue was pre-soaked in 0Ca²⁺-ASW containing 10 mmol l^-1 Co²⁺ for 1.5 h. 0.6 mol l^-1 KCl solution was added to the bath at the time indicated (+KCl), and the external solution was switched back to the original 0Ca²⁺-ASW containing 10 mmol l^-1 Co²⁺ at time (-KCl).