Volume regulation in the human airway epithelial cell line Calu-3

Abstract

Cells regulate their volume in response to changes in the osmolarity of both their extracellular and their intracellular environments. We investigated the ability of the human airway epithelial cell line Calu-3 to respond to changes in extracellular osmolarity. Although switching Calu-3 cells from an isosmotic to a hyperosmotic environment resulted in cell shrinkage, there was no compensatory mechanism for the cells to return to their original volume. In contrast, switching to a hyposmotic environment resulted in an initial cell swelling response, followed by a regulatory volume decrease (RVD). Pharmacologic studies demonstrate that the voltage-activated K+ channels Kv4.1 and (or) Kv4.3 play a crucial role in mediating this RVD response, and we demonstrated expression of these channel types at the mRNA and protein levels. Furthermore, inhibition of the large- and intermediate-conductance Ca2+-activated K+ channels KCa1.1 (maxi-K) and KCa3.1 (hIK) also implicated these channels as playing a role in volume recovery in Calu-3 cells. This report describes the nature of volume regulation in the widely used model cell line Calu-3.

Rho Signaling Regulates Pannexin 1-mediated ATP Release from Airway Epithelia

“…The inhibitory effect of carbenoxolone and 10 Panx1 on RVD likely reflected less ATP release. That is, ATP released from swollen cells promotes P2Y 2 receptor-mediated activation of intermediate-conductance Ca 2ϩ -dependent K ϩ channels, which are essential for the RVD response (21,47,48). These results are consistent with the notion that carbenoxolone and 10 Panx1 acted downstream of the hypotonic stress sensor but upstream of ATP releaseevoked RVD (21).…”

Cell type-specific adaptation of cellular and nuclear volume in micro-engineered 3D environments

“…Many different techniques have been applied to provide estimates of single cell volumes, including electrophysiological methods, interferometry, optical sectioning by confocal microscopy, light scattering detection, quantitative fluorescence or phase contrast microscopy, and AFM measurements [68]. Unfortunately, often only relative changes in volume are given, rather than absolute values which complicate the comparison between different studies [57,74,75]. We also realized that most studies only investigate the volume of single cells that are cultured either at 2D conditions or in 3D environments, while changes in cell and nuclear volume during the transition from 2D to 3D cell culture environments have rarely been reported.…”

Tracheal epithelium cell volume responses to hyperosmolar, isosmolar and hypoosmolar solutions: relation to epithelium-derived relaxing factor (EpDRF) effects

“…However, RVI was evident and consistent in hyperosmolar jump experiments performed on dispersed cells. Exposure of dispersed cells to halved osmolarity led to cell swelling accompanied by RVD, as observed in other cell types (Hallows et al, 1991; Pedersen et al, 1998; Nielsen et al, 2007), including Calu-3 cells (Harron et al, 2009). …”

“…In unstimulated, dispersed cells, amiloride and bumetanide had little or no effect on cell volume, while DIDS (but not NPPB) reduced cell volume. Amiloride and DIDS inhibited modestly cell shrinkage in response to hyperosmolar challenge with D-M. DIDS had no effect on RVD in Calu-3 cells (Harron et al, 2009). Because Na + and Cl − transport are associated with EpDRF release and inhibit cell volume decrease, these findings are evidence that cell shrinkage could be required for EpDRF release.…”