An endogenous acid-sensitive K+ channel expressed in COS-7 cells
Dawon Kang1, Jun-Ho La, Eun-Jin Kim
1Department of Physiology, College of Medicine and Institute of Health Science, Gyeongsang National University, Jinju 660-751, Republic of Korea.
Abstract:
COS-7 cells originally isolated from monkey kidney and used in many transfection studies were found to express a background K+ channel and therefore, its biophysical and pharmacological properties were examined. In cell-attached patches, a 32-pS K+ channel with a linear current-voltage relationship could be recorded. The open probability was highly voltage-dependent, with greater channel activity at depolarized potentials. The channel was markedly sensitive to changes in extracellular pH (pH(o)), showing a 70+/-10% inhibition by changing the pH(o) from 7.3 to 6.3. Arachidonic acid (5 microM) augmented channel activity 12-fold. Applying negative pressure (-40 mmHg) to the membrane patch also increased channel activity by 4-fold. These results show that COS-7 cells express a K+ channel with unique properties that must be considered when using these cells as transfection system.
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