Chloride and sodium transport across bovine ciliary body/epithelium (CBE).
OBJECTIVE
To study the chloride and sodium ion transports across the bovine ciliary body/epithelium (CBE) by a modified Ussing-Zerahn type chamber.


METHODS
Isolated bovine CBE preparations were mounted in a modified Ussing-type chamber and the transepithelial electrical parameters were monitored. The inward (stroma to aqueous) and outward (aqueous to stroma) fluxes of 36[Cl] chloride and 22[Na] sodium ions across the CBE were measured under short-circuited conditions. The effect of 0.1 mM of furosemide and bumetanide on the chloride transport were studied.


RESULTS
The potential difference (PD), the resistance and the short-circuit current (SCC) across the isolated bovine ciliary body were found to be -0.20+/-0.01 mV (aqueous negative), 75+/-1 omegacm2 and -2.70+/-0.17 microAcm(-2) (mean+/-SEM, n=50) respectively. A statistically significant net inward chloride ion flux of 1.12+/-0.41 microEq h(-1)cm(-2) (p < 0.01) was found (n=15). The net chloride transport was abolished when 0.1 mM furosemide (82% inhibition) and 0.1 mM bumetanide (100% inhibition) were applied bilateral. No significant net sodium ion flux was detected.


CONCLUSIONS
Electrolyte and fluid transport across the bovine CBE may be via a bumetanide and furosemide-sensitive chloride transport mechanism. The Na-K-2Cl cotransporter plays a significant role in the trans-CBE chloride transport. The net chloride flux/current was about 12 times higher than the measured SCC, suggesting that the chloride ion transport may be coupled to other ion species.
To
C H
CH
Department of Optometry and Radiography, The Hong Kong Polytechnic University, China.
Mok
K H
KH
Do
C W
CW
Lee
K L
KL
Millodot
M
M
D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D002712:Chlorides / Q000378:metabolism*; D002924:Ciliary Body / Q000187:drug effects / Q000378:metabolism*; D015194:Diffusion Chambers, Culture; D004594:Electrophysiology; D005665:Furosemide / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D049992:Sodium Chloride Symporters; D028021:Sodium-Potassium-Chloride Symporters; D027981:Symporters
D002352:Carrier Proteins; D002712:Chlorides; D049992:Sodium Chloride Symporters; D028021:Sodium-Potassium-Chloride Symporters; D027981:Symporters; D002034:Bumetanide; D010042:Ouabain; D005665:Furosemide; D012964:Sodium