A 67-year-old woman with COPD is seen at a follow-up appointment one week after being started on scheduled nebulized albuterol every 4 hours for a COPD exacerbation. She now notices her hands shaking and feels her heart "fluttering." She takes no diuretics, laxatives, or other new medications, and she denies diarrhea or vomiting. On examination, her heart rate is 108 bpm and fine bilateral hand tremors are present. Serum potassium is 3.1 mEq/L; sodium, creatinine, and bicarbonate are within normal limits.
Which of the following best explains the mechanism of the hypokalemia in this patient?