High proximal excretion of sodium during activation of beta 2-adrenoreceptors in humans.

ABSTRACT

The effects of acute beta 2-type adrenoreceptor activation with intravenous albuterol on plasma and urinary sodium, potassium, calcium, magnesium, phosphate and lithium were investigated in 9 volunteers during acute hydration. When compared with the control infusion with inactive vehicle, beta 2-type adrenoreceptor activation decreased plasma and urinary potassium and phosphate and increased the excretion of calcium and magnesium. In addition, activation of the beta 2 adrenoreceptors did not influence creatinine clearance and plasma level and the net fractional excretion of sodium but increased the fractional clearance of exogenous lithium which measures the fraction of filtered sodium delivered by the proximal tubule. The results indicate that activation of beta 2-type adrenoreceptors decreases the proximal reabsorption of sodium.