BUMETANIDE AND BICARBONATE INCREASE SHORT-CIRCUIT CURRENT IN FETAL LUNG EPITHELIUM

1. We studied the effects of bumetanide (a Na+/K+/2Cl(-) cotransport i nhibitor) and HCO3- on beta-adrenergic-agonist-stimulated short-circui t current (beta-I-sc) in rat fetal distal lung epithelium (FDLE). 2. B umetanide significantly increased beta-I-sc in the absence of amilorid e but decreased it in its presence. The amiloride- and bumetanide-inse nsitive beta-I-sc was diminished by a removal of HCO3- in the bathing solution. 3. Our results suggest that bumetanide stimulates the amilor ide-sensitive beta-I-sc in FDLE and that the amiloride-insensitive bet a-I-sc is composed of two different pathways: bumetanide-sensitive and HCO3--dependent Cl- secretion in FDLE.