Bumetanide and bicarbonate increase short-circuit current in fetal lung epithelium

Abstract 1. 1. We studied the effects of bumetanide (a Na + /K + /2Cl - cotransport inhibitor) and HCO 3 - on β-adrenergic-agonist-stimulated short-circuit current (β-I sc ) in rat fetal distal lung epithelium (FDLE). 2. 2. Bumetanide significantly increased β-I sc in the absence of amiloride but decreased it in its presence. The amiloride- and bumetanide-insensitive β-I sc was diminished by a removal of HCO 3 - in the bathing solution. 3. 3. Our results suggest that bumetanide stimulates the amiloride-sensitive β-I sc in FDLE and that the amiloride-insensitive β-I sc is composed of two different pathways: bumetanide-sensitive and HCO 3 - -dependent Cl - secretion in FDLE.