CS exposure had no effect on the basal PD (pre-CS PD was 21.8��1.8 mV, post-CS PD was 21.9��2.8 mV; P=0.98). The amiloride-sensitive NPD was not significantly raised (Fig. 1B, C). However, the change in NPD in response to a low Cl?/ISO superfusion, as an index of CFTR-mediated Cl? secretory capacity, was reduced by ~60% after CS, as compared to selleck compound room air (Fig. 1B, C). This finding suggests that the CFTR-mediated Cl? secretory capacity had been diminished by CS in vivo. Some recovery in the ��ISO NPD occurred after 45 min post-CS. Room air exposure had no significant effect on any in vivo bioelectric property over time (Fig. 1D). Thus, we conclude that CS exposure rapidly inhibits CFTR activity in vivo.

Effect of CS on ASL hydration in vitro Normal airway epithelia balance Na+ absorption and Cl? secretion to maintain a volume of ASL sufficient to hydrate mucus for effective clearance (12). HBECs were exposed to CS from 1 cigarette or room air (control) to study the acute effects of CS on the regulation of ASL volume/height. No effect of CS on HBEC morphology was observed (Fig. 2A). However, the CS from 1 cigarette caused an acute reduction in ASL volume/height that lasted for >2.5 h (Fig. 2B). Figure 2. Effect of CS on airway epithelial CFTR function and airway hydration. A) Light micrographs of paraformaldehyde-fixed HBECs after 10 min air (control) or CS exposure. Bi) Confocal images of ASL height (red) in air-exposed (control) or CS-exposed HBECs. … To elucidate the mechanisms of CS-induced ASL volume depletion, we first measured the transepithelial bioelectric correlates of ion transport.

CS did not reduce transepithelial resistance Rt, suggesting that the ASL volume reduction did not reflect nonspecific effects on the paracellular path (Fig. 2Ci). In contrast, CS decreased the transepithelial electric potential difference Vt, suggesting that, in the absence of a change in Rt, a reduction in the rate of active ion transport had occurred (Fig. 2Cii). Because a reduction of Na+ transport would increase ASL volume rather than decrease it, we investigated whether CS inhibited the Cl? secretory paths that support Cl? secretion and ASL volume expansion. CS blunted the ��Vt response to ADO, but not ATP, suggesting that CS blocked the ADO-A2b-cAMP-CFTR-, but not ATP-P2Y2-R-Ca2+-activated Cl? channel secretion pathway (Fig. Drug_discovery 2Ciii). We next investigated directly the regulation of ASL height/volume by Cl? secretagogues after exposure to CS (Fig. 2D). ADO increased ASL volume in room air but not CS-exposed airway cultures (Fig. 2D).