PDE4A and Hypokalemia: Nevertheless, treatment with PDE4 inhibitors produces similar effects on serum potassium levels in anesthetized and awake mice, suggesting that the PDE4 inhibitor-induced hypokalemia is not caused by changes in neuronal signaling, and supporting the idea of a transcellular shift of potassium caused locally (e.g., amplification of β-adrenergic cAMP signaling within skeletal muscle cells).