title: Use of microphysiometry for analysis of heterologous ion channels expressed in yeast.
abstract: Measurement of extracellular acidification rates by microphysiometry provides a means to analyze the function of ion channels expressed in yeast cells. These measurements depend on the proton pumping action of the H(+)-ATPase, a central component of the yeast plasma membrane. We used microphysiometry to analyze the activity of two ion channels expressed in yeast. In one example, an inwardly rectifying K+ channel, gpIRK1, provides a potassium uptake function when expressed in a potassium transporter-defective yeast strain. Rates of acidification in gpIRK1-expressing cells directly reflect channel function. Addition of cesium, an inhibitor of gpIRK1 activity, results in an immediate reduction in acidification rates. In a second example, expression of a nonselective cation channel, the influenza virus M2 protein, is believed to interfere with the maintenance of the electrochemical proton gradient by the H(+)-ATPase. In cells expressing the M2 channel, addition of inhibitors increases the rate of proton extrusion. Moreover, functional differences between two M2 inhibitors, amantadine and BL-1743, are distinguished by the microphysiometer. This application demonstrates the utility of the microphysiometer for functional studies of ion channels; it is adaptable to a screening process for compounds that modulate ion channel activity.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, WA 98121, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Hahnenberger
authors.forename: M
authors.initials: M
authors.lastname: Krystal
authors.forename: K
authors.initials: K
authors.lastname: Esposito
authors.forename: W
authors.initials: W
authors.lastname: Tang
authors.forename: S
authors.initials: S
authors.lastname: Kurtz
mesh_terms: D015374:Biosensing Techniques; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D011199:Potentiometry / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins