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Renal brush-border chloride transport mechanisms characterized using a fluorescent indicator
P Y Chen1, N P Illsley, A S Verkman
1Division of Nephrology and Cardiovascular Research Institute, University of California, San Francisco 94143.
The American Journal of Physiology
|January 1, 1988
Summary
Chloride transport in kidney vesicles is driven by proton gradients and chloride channels, not sodium. This research clarifies renal chloride uptake mechanisms.
Area of Science:
- Renal Physiology
- Membrane Transport
- Biochemistry
Background:
- Brush-border membrane vesicles (BBMV) are crucial for studying renal transport.
- Understanding chloride (Cl) transport is vital for kidney function and electrolyte balance.
Purpose of the Study:
- To characterize Cl transport mechanisms in rabbit renal cortex BBMV.
- To investigate the influence of ion gradients and specific inhibitors on Cl flux.
Main Methods:
- Utilized the Cl-sensitive fluorescent indicator 6-methoxy-N-[3-sulfopropyl]quinolinium (SPQ).
- Measured Cl fluxes (JCl) using SPQ fluorescence, calibration, and vesicle glucose space.
- Employed ion gradients (Cl, Na, H) and inhibitors (H2DIDS, DPC) to probe transport pathways.
Main Results:
- A 50 mM inwardly directed Cl gradient resulted in JCl of 0.26 nmol.s-1.mg-1.
- Proton gradients significantly increased JCl, an effect blocked by H2DIDS.
- The Cl channel blocker DPC inhibited K valinomycin-induced JCl and blocked Br/I transport.
Conclusions:
- Renal Cl transport in BBMV is primarily driven by proton gradients and chloride channels.
- Sodium gradients do not significantly affect Cl flux.
- H2DIDS and DPC act as effective inhibitors of specific Cl transport pathways.