Effects of somatostatin and oral potassium administration on terbutaline-induced hypokalemia.

Terbutaline, a beta 2-adrenergic agonist, has been shown to cause hypokalemia and an increase of plasma glucose and serum insulin concentrations. We considered that terbutaline-induced hypokalemia may be due to the insulin-induced shift of potassium (K+) from the extracellular to the intracellular space. If so, then inhibition of insulin secretion by somatostatin would prevent terbutaline-induced hypokalemia. Further, we wondered whether oral potassium pretreatment could prevent terbutaline-induced hypokalemia. Therefore, 10 healthy volunteers (5 men, 5 women; mean age, 23 yr +/- 3 SD) received either sodium chloride (NaCl) or somatostatin intravenously together with 0.25 mg terbutaline subcutaneously in a double-blind crossover design. On a third test day, they received 39 mval of K+ powder orally before terbutaline injection in an open trial. Terbutaline caused a significant decrease of K+ (from 3.96 +/- 0.08 to 3.3 +/- 0.13 mmol/L +/- SEM; p less than 0.0005), accompanied by a significant increase in plasma glucose (from 83 +/- 3.6 to 101 +/- 4.4 mg/dl +/- SEM; p less than 0.01) and serum insulin concentrations (from 11.7 +/- 0.9 to 19.9 +/- 1.1 microU/ml +/- SEM; p less than 0.001), confirming earlier data. Somatostatin pretreatment inhibited the terbutaline-induced hypokalemia; the small fall of K+ (from 3.7 +/- 0.08 to 3.5 +/- 0.2 mmol/L) was no longer significant. Insulin secretion was completely blocked by somatostatin, leading to an even more pronounced increase of blood glucose. Hypokalemia after terbutaline injection was not prevented by oral potassium pretreatment. In summary, the present findings confirm that terbutaline-induced hypokalemia is associated with increased plasma glucose and insulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)