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Updated: Jul 13, 2026
07:19
Recording of Inward Rectifying K+ Currents in Freshly Isolated Basilar Artery Smooth Muscle Cells by Patch Clamp Technique
Published on: February 7, 2025
Descending vasa recta endothelia express inward rectifier potassium channels
Chunhua Cao1, Whaseon Lee-Kwon, Kristie Payne
1Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
American Journal of Physiology. Renal Physiology
|August 3, 2007
Summary
Inward rectifier potassium channels (KIR) in descending vasa recta (DVR) endothelium mediate potassium-induced hyperpolarization and affect intracellular calcium levels. These findings are crucial for understanding renal blood flow regulation.
Area of Science:
- Renal Physiology
- Cardiovascular Research
- Cellular Electrophysiology
Background:
- Descending vasa recta (DVR) are critical microvessels supplying the renal medulla.
- DVR function relies on endothelial cells and pericytes, but their electrophysiological properties are poorly understood.
- Inward rectifier potassium channels (KIR) are known to influence cell membrane potential and ion transport.
Purpose of the Study:
- To investigate the presence and function of KIR channels in DVR endothelial cells.
- To determine the effect of KIR channels on endothelial membrane potential and intracellular calcium concentration ([Ca2+]cyt).
- To identify specific KIR channel subunits expressed in DVR.
Main Methods:
- Whole-cell patch-clamp electrophysiology on isolated DVR endothelial cells.
- Pharmacological blockade of KIR currents using barium (Ba2+) and cesium (Cs+).
- Assessment of membrane potential and [Ca2+]cyt changes in response to altered extracellular potassium (K+) concentrations.
- Immunochemical staining for KIR channel subunits.
Main Results:
- Large, inwardly rectifying KIR currents were identified in DVR endothelial cells.
- Barium and cesium ions potently inhibited these KIR currents in a voltage-dependent manner.
- Increased extracellular K+ induced membrane hyperpolarization and elevated [Ca2+]cyt, effects reversible by Ba2+.
- Immunostaining confirmed expression of KIR2.1, KIR2.2, and KIR2.3 subunits in DVR endothelial cells and pericytes.
Conclusions:
- DVR endothelium expresses functional inward rectifier potassium channels, primarily KIR2.x isoforms.
- These KIR channels mediate K+-induced hyperpolarization of the DVR endothelium.
- KIR channel activity influences endothelial intracellular calcium levels, impacting DVR function.
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