Protection against severe hypokalemia but impaired cardiac repolarization after intense rowing exercise in healthy humans receiving salbutamol

Intense exercise induces pronounced hyperkalemia, followed by transient hypokalemia in recovery. We investigated whether the β -agonist salbutamol attenuated the exercise-hyperkalemia, and exacerbated the post-exercise hypokalemia, and whether hypokalemia was associated with impaired cardiac repolarization (QT hysteresis). Eleven healthy adults participated in a randomized, counterbalanced, double-blind trial receiving either 1000 µg salbutamol (SAL) or placebo (PLAC) by inhalation. Arterial plasma potassium concentration ([K ] ) was measured at rest, during 3 min intense rowing exercise and 60 min recovery. QT hysteresis was calculated from ECG (n=8). [K ] increased above baseline during exercise (rest, 3.72{plus minus}0.7 vs end-exercise, 6.81{plus minus}1.4 mM, P