Physiologymiddle twist
A 58-year-old man is freed after six hours trapped beneath a collapsed brick wall. He is alert, and both thighs are swollen and tender. He reports tingling in both hands and cannot lift his arms against gravity.
Serum potassium 7.4 mmol/L (3.5-5.2) Serum sodium 139 mmol/L (135-145)
His electrocardiogram shows tall peaked T waves.
In this man's skeletal muscle fibres, which one of the following pairs of changes would you expect?