The Effect of Chronic Frusemide Administration on Intracellular Potassium, Sodium and pH of Cardiac and Skeletal Muscle

1. Chronic administration of frusemide in large doses of 4 mg day⁻¹ kg⁻¹ for 3 weeks caused a significant reduction of cell water in rabbit cardiac and skeletal muscle. Intracellular Na⁺ concentration, intracellular pH and extracellular space were unchanged in both tissues. Intracellular K⁺ concentration increased slightly in both cardiac and skeletal muscle.

2. It is concluded that frusemide does not reduce intracellular K⁺ concentration in cardiac or skeletal muscle of normal animals receiving a normal oral potassium intake.