Adrenaline causes hypokalaemia in man by beta 2 adrenoceptor stimulation.

Increased circulating adrenaline produces systemic hypokalaemia by the stimulation of a membrane bound Na/K ATPase. In man, this enzyme appears to be linked to an adrenoceptor of the beta-subtype. We have further studied the subtype of beta-adrenoceptor involved by infusing adrenaline intravenously in normal volunteers after pretreatment with either a selective beta 2 antagonist (ICI 118551) or placebo. During the adrenaline infusion the serum potassium fell from 4.08 +/- 0.21 to 3.32 +/- 0.25 mmol/l (P less than 0.002). This adrenaline induced hypokalaemia was completely blocked by ICI 118551 (3.82 +/- 0.13 to 4.03 +/- 0.22 mmol/l, NS). Adrenaline also caused electrocardiographic changes of T wave flattening (-1.8 +/- 1.5 mm, P less than 0.05) whereas the T wave height increased after ICI 118551 (+ 1.0 +/- 0.9 mm, P less than 0.05). This suggests that adrenaline acts via beta 2 adrenoceptors in man to cause potassium influx and systemic hypokalaemia.