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 of isosmolar solutions of ionic permeant and impermeant osmolytes on volume of dispersed epithelial cells. Cell volume was measured after the cells were placed into isosmolar solutions containing NaCl (A; n = 6), NMDG-Cl (C; n = 6), Na-Glu (E; n = 6), NMDG-Glu (G; n = 6), K-Glu (B; n = 6), K2SO4(D; n = 6), KBr (F; n = 6), and KCl (H; n = 6). The order of increasing effectiveness at causing volume change was: K2SO4 = KGlu = NMDG-Cl (~15% decrease) < Na-Glu < NMDG-Glu (35% decrease). KCl and KBr caused increases in cell volume (~50 and 15%, respectively). D-M and urea could not be studied using this method. *Significantly different compared to t = 0 min.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Effects of isosmolar solutions of ionic permeant and impermeant osmolytes on volume of dispersed epithelial cells. Cell volume was measured after the cells were placed into isosmolar solutions containing NaCl (A; n = 6), NMDG-Cl (C; n = 6), Na-Glu (E; n = 6), NMDG-Glu (G; n = 6), K-Glu (B; n = 6), K2SO4(D; n = 6), KBr (F; n = 6), and KCl (H; n = 6). The order of increasing effectiveness at causing volume change was: K2SO4 = KGlu = NMDG-Cl (~15% decrease) < Na-Glu < NMDG-Glu (35% decrease). KCl and KBr caused increases in cell volume (~50 and 15%, respectively). D-M and urea could not be studied using this method. *Significantly different compared to t = 0 min.

Mentions: Isosmolar NaCl did not significantly affect cell volume (Figure 3A), although a small decrease was seen consistently. Isosmolar NMDG-Cl (Figure 3C) containing the impermeant cation produced a comparable cell shrinkage that was significant. Replacement of Cl− with the impermeant anion Glu in Na-Glu (Figure 3E) caused a greater shrinkage response than NaCl or NMDG-Cl. Replacement of Na with NMDG along with substitution of Cl− with Glu (Figure 3G) resulted in a large shrinkage response (~35%). (D-M and urea could not be examined because cell sizing is dependent on solute conductivity).


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 of isosmolar solutions of ionic permeant and impermeant osmolytes on volume of dispersed epithelial cells. Cell volume was measured after the cells were placed into isosmolar solutions containing NaCl (A; n = 6), NMDG-Cl (C; n = 6), Na-Glu (E; n = 6), NMDG-Glu (G; n = 6), K-Glu (B; n = 6), K2SO4(D; n = 6), KBr (F; n = 6), and KCl (H; n = 6). The order of increasing effectiveness at causing volume change was: K2SO4 = KGlu = NMDG-Cl (~15% decrease) < Na-Glu < NMDG-Glu (35% decrease). KCl and KBr caused increases in cell volume (~50 and 15%, respectively). D-M and urea could not be studied using this method. *Significantly different compared to t = 0 min.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Effects of isosmolar solutions of ionic permeant and impermeant osmolytes on volume of dispersed epithelial cells. Cell volume was measured after the cells were placed into isosmolar solutions containing NaCl (A; n = 6), NMDG-Cl (C; n = 6), Na-Glu (E; n = 6), NMDG-Glu (G; n = 6), K-Glu (B; n = 6), K2SO4(D; n = 6), KBr (F; n = 6), and KCl (H; n = 6). The order of increasing effectiveness at causing volume change was: K2SO4 = KGlu = NMDG-Cl (~15% decrease) < Na-Glu < NMDG-Glu (35% decrease). KCl and KBr caused increases in cell volume (~50 and 15%, respectively). D-M and urea could not be studied using this method. *Significantly different compared to t = 0 min.
Mentions: Isosmolar NaCl did not significantly affect cell volume (Figure 3A), although a small decrease was seen consistently. Isosmolar NMDG-Cl (Figure 3C) containing the impermeant cation produced a comparable cell shrinkage that was significant. Replacement of Cl− with the impermeant anion Glu in Na-Glu (Figure 3E) caused a greater shrinkage response than NaCl or NMDG-Cl. Replacement of Na with NMDG along with substitution of Cl− with Glu (Figure 3G) resulted in a large shrinkage response (~35%). (D-M and urea could not be examined because cell sizing is dependent on solute conductivity).

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