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

Fedan JS, Thompson JA, Ismailoglu UB, Jing Y - Front Physiol (2013)

Bottom Line: Little is known of ASL hyperosmolarity effects on epithelial function.In previous studies amiloride and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells.Except for gadolinium and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells.

View Article: PubMed Central - PubMed

Affiliation: Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health Morgantown, WV, USA.

ABSTRACT
In asthmatic patients, inhalation of hyperosmolar saline or D-mannitol (D-M) elicits bronchoconstriction, but in healthy subjects exercise causes bronchodilation. Hyperventilation causes drying of airway surface liquid (ASL) and increases its osmolarity. Hyperosmolar challenge of airway epithelium releases epithelium-derived relaxing factor (EpDRF), which relaxes the airway smooth muscle. This pathway could be involved in exercise-induced bronchodilation. Little is known of ASL hyperosmolarity effects on epithelial function. We investigated the effects of osmolar challenge maneuvers on dispersed and adherent guinea-pig tracheal epithelial cells to examine the hypothesis that EpDRF-mediated relaxation is associated with epithelial cell shrinkage. Enzymatically-dispersed cells shrank when challenged with ≥10 mOsM added D-M, urea or NaCl with a concentration-dependence that mimics relaxation of the of isolated perfused tracheas (IPT). Cells shrank when incubated in isosmolar N-methyl-D-glucamine (NMDG) chloride, Na gluconate (Glu), NMDG-Glu, K-Glu and K2SO4, and swelled in isosmolar KBr and KCl. However, isosmolar challenge is not a strong stimulus of relaxation in IPTs. In previous studies amiloride and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells. Confocal microscopy in tracheal segments showed that adherent epithelium is refractory to low hyperosmolar concentrations that induce dispersed cell shrinkage and relaxation of IPT. Except for gadolinium and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells. Our studies dissociate relaxation of IPT from cell shrinkage after hyperosmolar challenge of airway epithelium.

No MeSH data available.


Related in: MedlinePlus

Effects EHNA (5 × 10−4 M) on cell volume and volume responses to D-M. Left panel (Basal response): % reduction in volume under basal conditions after addition of DMSO or EHNA dissolved in DMSO, during the 30 min incubation period. Right panel (D-M induced response): % reduction in volume after subsequent addition of 120 mOsM D-M dissolved in DMSO. In these experiments a control volume measurement was made before incubating the cells with vehicle or agents; the cells used in each replicate were from the same preparation. *Significantly different from D-M. Basal response, n = 4; DMSO-induced response.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3795350&req=5

Figure 12: Effects EHNA (5 × 10−4 M) on cell volume and volume responses to D-M. Left panel (Basal response): % reduction in volume under basal conditions after addition of DMSO or EHNA dissolved in DMSO, during the 30 min incubation period. Right panel (D-M induced response): % reduction in volume after subsequent addition of 120 mOsM D-M dissolved in DMSO. In these experiments a control volume measurement was made before incubating the cells with vehicle or agents; the cells used in each replicate were from the same preparation. *Significantly different from D-M. Basal response, n = 4; DMSO-induced response.

Mentions: In preliminary experiments, DMSO, the solvent for most of these agents, reduced cell volume even at the lowest concentration (0.1%) needed to dissolve the inhibitors. Therefore, a DMSO control was included in every experiment. EHNA dissolved in DMSO produced less cell shrinkage than DMSO itself (Figure 12); the other agents had no effect compared to control (DMSO or vehicle control; not shown). After incubation with DMSO or agent dissolved in DMSO, 120 mOsM D-M in DMSO vehicle-containing MKH solution was added and cell volume was measured. EHNA inhibited responses to D-M (Figure 12). In these experiments colchicine, cytochalasins B (n = 6) and D (n = 6), nocodazole (n = 4) and latrunculin B (n = 4) had no effect (not shown). These findings agree with the lack of effect of these inhibitors on cell volume responses to hyperosmolar challenge in other cells (Foskett and Spring, 1985; Hallows et al., 1991, 1996).


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

Fedan JS, Thompson JA, Ismailoglu UB, Jing Y - Front Physiol (2013)

Effects EHNA (5 × 10−4 M) on cell volume and volume responses to D-M. Left panel (Basal response): % reduction in volume under basal conditions after addition of DMSO or EHNA dissolved in DMSO, during the 30 min incubation period. Right panel (D-M induced response): % reduction in volume after subsequent addition of 120 mOsM D-M dissolved in DMSO. In these experiments a control volume measurement was made before incubating the cells with vehicle or agents; the cells used in each replicate were from the same preparation. *Significantly different from D-M. Basal response, n = 4; DMSO-induced response.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3795350&req=5

Figure 12: Effects EHNA (5 × 10−4 M) on cell volume and volume responses to D-M. Left panel (Basal response): % reduction in volume under basal conditions after addition of DMSO or EHNA dissolved in DMSO, during the 30 min incubation period. Right panel (D-M induced response): % reduction in volume after subsequent addition of 120 mOsM D-M dissolved in DMSO. In these experiments a control volume measurement was made before incubating the cells with vehicle or agents; the cells used in each replicate were from the same preparation. *Significantly different from D-M. Basal response, n = 4; DMSO-induced response.
Mentions: In preliminary experiments, DMSO, the solvent for most of these agents, reduced cell volume even at the lowest concentration (0.1%) needed to dissolve the inhibitors. Therefore, a DMSO control was included in every experiment. EHNA dissolved in DMSO produced less cell shrinkage than DMSO itself (Figure 12); the other agents had no effect compared to control (DMSO or vehicle control; not shown). After incubation with DMSO or agent dissolved in DMSO, 120 mOsM D-M in DMSO vehicle-containing MKH solution was added and cell volume was measured. EHNA inhibited responses to D-M (Figure 12). In these experiments colchicine, cytochalasins B (n = 6) and D (n = 6), nocodazole (n = 4) and latrunculin B (n = 4) had no effect (not shown). These findings agree with the lack of effect of these inhibitors on cell volume responses to hyperosmolar challenge in other cells (Foskett and Spring, 1985; Hallows et al., 1991, 1996).

Bottom Line: Little is known of ASL hyperosmolarity effects on epithelial function.In previous studies amiloride and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells.Except for gadolinium and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells.

View Article: PubMed Central - PubMed

Affiliation: Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health Morgantown, WV, USA.

ABSTRACT
In asthmatic patients, inhalation of hyperosmolar saline or D-mannitol (D-M) elicits bronchoconstriction, but in healthy subjects exercise causes bronchodilation. Hyperventilation causes drying of airway surface liquid (ASL) and increases its osmolarity. Hyperosmolar challenge of airway epithelium releases epithelium-derived relaxing factor (EpDRF), which relaxes the airway smooth muscle. This pathway could be involved in exercise-induced bronchodilation. Little is known of ASL hyperosmolarity effects on epithelial function. We investigated the effects of osmolar challenge maneuvers on dispersed and adherent guinea-pig tracheal epithelial cells to examine the hypothesis that EpDRF-mediated relaxation is associated with epithelial cell shrinkage. Enzymatically-dispersed cells shrank when challenged with ≥10 mOsM added D-M, urea or NaCl with a concentration-dependence that mimics relaxation of the of isolated perfused tracheas (IPT). Cells shrank when incubated in isosmolar N-methyl-D-glucamine (NMDG) chloride, Na gluconate (Glu), NMDG-Glu, K-Glu and K2SO4, and swelled in isosmolar KBr and KCl. However, isosmolar challenge is not a strong stimulus of relaxation in IPTs. In previous studies amiloride and 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells. Confocal microscopy in tracheal segments showed that adherent epithelium is refractory to low hyperosmolar concentrations that induce dispersed cell shrinkage and relaxation of IPT. Except for gadolinium and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells. Our studies dissociate relaxation of IPT from cell shrinkage after hyperosmolar challenge of airway epithelium.

No MeSH data available.


Related in: MedlinePlus