Biphasic rises in cytosolic free Ca2+ in association with activation of K+ and Cl? conductance during the regulatory volume decrease in cultured human epithelial cells

1990 ◽  
Vol 416 (6) ◽  
pp. 710-714 ◽  
Author(s):  
Akihiro Hazama ◽  
Yasunobu Okada
Keyword(s):  
Epithelial Cells ◽  
Regulatory Volume Decrease ◽  
Human Epithelial Cells ◽  
Cl Conductance ◽  
Volume Decrease

Effect of osmotic swelling on K+ conductance in jejunal crypt epithelial cells

1992 ◽  
Vol 262 (6) ◽  
pp. G1021-G1026 ◽  
Author(s):  
R. J. MacLeod ◽  
P. Lembessis ◽  
J. R. Hamilton
Keyword(s):  
Epithelial Cells ◽  
Regulatory Volume Decrease ◽  
Channel Blockers ◽  
Osmotic Swelling ◽  
Hypotonic Stress ◽  
Cell Sizing ◽  
Hypotonic Swelling ◽  
Cl Conductance ◽  
Volume Decrease ◽  
Crypt Cells

To further elucidate differences in ion transport properties between jejunal crypt and villus cells, we compared the responses of purified cell suspensions to hypotonic stress using electronic cell sizing to evaluate volume changes and 86Rb and 36Cl efflux. After hypotonic swelling, villus enterocytes undergo a regulatory volume decrease (RVD) due to the loss of K+ and Cl- through volume-activated conductances. After 0.6x isotonic challenge in Na(+)-free medium, crypt cells exhibited only partial RVD, with t1/2 congruent to 15 min. The addition of a cation ionophore, gramicidin (0.25 microM), to hypotonically swollen crypt cells caused an accelerated RVD, which was complete with t1/2 congruent to 5 min. Crypt epithelial cells showed no volume-activated 86Rb efflux, but villus enterocytes had an increased rate of 86Rb efflux after hypotonic dilution (P less than 0.001). Gramicidin added to hypotonically diluted crypt cells greatly increased the rate of 86Rb efflux compared with controls. Both villus (30 s; P less than 0.005) and crypt (2 min; P less than 0.001) cells exhibited volume-activated 36Cl efflux in absence of gramicidin. Cl- channel blockers anthracene-9-carboxylate (9-AC, 300 microM) and indanyloxyacetic acid (IAA-94, 100 microM) prevented crypt RVD (P less than 0.001) in the presence of gramicidin. Ouabain (P less than 0.001) or K(+)-free Na(+)-containing medium, but not Ba2+ (5 mM) or quinine (100 microM), prevented crypt partial RVD. We conclude that crypt cells lack volume-activated K+ conductance. The RVD exhibited by crypt cells, although partial, was due to Cl- loss through a volume-activated Cl- conductance and Na+ loss via Na(+)-K(+)-ATPase.

IK channels are involved in the regulatory volume decrease in human epithelial cells

2003 ◽  
Vol 284 (1) ◽  
pp. C77-C84 ◽  
Author(s):  
Jun Wang ◽  
Shigeru Morishima ◽  
Yasunobu Okada
Keyword(s):  
Epithelial Cells ◽  
Regulatory Volume Decrease ◽  
Bk Channels ◽  
Bk Channel ◽  
Channel Blockers ◽  
Hypotonic Stress ◽  
Human Epithelial Cells ◽  
Ik Channel ◽  
Inside Out ◽  
Volume Decrease

Parallel activation of Ca2+-dependent K+ channels and volume-sensitive Cl− channels is known to be responsible for KCl efflux during regulatory volume decrease (RVD) in human epithelial Intestine 407 cells. The present study was performed to identify the K+ channel type. RT-PCR demonstrated mRNA expression of Ca2+-activated, intermediate conductance K+(IK), but not small conductance K+ (SK1) or large conductance K+ (BK) channels in this cell line. Whole cell recordings showed that ionomycin or hypotonic stress activated inwardly rectifying K+ currents that were reversibly blocked by IK channel blockers [clotrimazole (CLT) and charybdotoxin] but not by SK and BK channel blockers (apamin and iberiotoxin). Inside-out recordings revealed the existence of CLT-sensitive single K+-channel activity, which exhibited an intermediate unitary conductance (30 pS at −100 mV). The channel was activated by cytosolic Ca2+ in inside-out patches and by a hypotonic challenge in cell-attached patches. The RVD was suppressed by CLT, but not by apamin or iberiotoxin. Thus we conclude that the IK channel is involved in the RVD process in these human epithelial cells.

scholarly journals Differential dependence of regulatory volume decrease behavior in rabbit corneal epithelial cells on MAPK superfamily activation

2007 ◽  
Vol 84 (5) ◽  
pp. 978-990 ◽  
Author(s):  
Zan Pan ◽  
José E. Capó-Aponte ◽  
Fan Zhang ◽  
Zheng Wang ◽  
Kathryn S. Pokorny ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Regulatory Volume Decrease ◽  
Corneal Epithelial Cells ◽  
Corneal Epithelial ◽  
Volume Decrease
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