The mechanism of salbutamol-induced hypokalaemia

The following four intravenous treatments were administered in a balanced, randomized Latin square design to eight healthy volunteers: (-)-adrenaline (0.06 microgram kg-1 min-1 for 90 min) + vehicle control (+)-glucose infusion (60 min), salbutamol (120 ng kg-1 min-1 for 30 min) + vehicle control (+)-glucose infusion (90 min), (-)-adrenaline (0.06 microgram kg-1 min-1 for 90 min) + salbutamol (120 ng kg-1 min-1 for 30 min) and two vehicle control infusions of (+)-glucose. All active solutions were preceded by a 1 h control infusion and the control infusion was continued for 1 h following the active solutions. Both the active solutions, (-)-adrenaline and salbutamol were increased stepwise to the above doses. Heart rate and blood pressure were recorded at frequent intervals throughout and venous blood was taken for the estimation of potassium, insulin, glucose, catecholamine and salbutamol levels. Adrenaline levels similar to those seen in acute illness were achieved using this infusion protocol. Salbutamol levels rose throughout the period of the salbutamol infusions and steady-state was not achieved. Potassium levels were unchanged on the control + control study day and fell on all active treatments (0.45 mmol l-1 following (-)-adrenaline + control; 0.48 mmol l-1 following salbutamol + control; 0.93 mmol l-1 following (-)-adrenaline + salbutamol). Insulin levels rose insignificantly after salbutamol alone and fell slightly on all other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)