Immediate changes in pH. (A) Representative single twitches before and after changing extracellular pH. No obvious reduction of developed tension is visible. (B) Representative single twitches after an acute pH change show a decrease of absolute developed tension due to mild metabolic acidosis. (C) Mean values of relative force amplitude before and after pH change show a significant decrease of force amplitude after changing to the mild acidotic solution. (D) Time to 90% relaxation before and after pH solution change yielded no statistical difference.