Transient hyperpolarization of yeast by glucose and ethanol.
At pH 7, addition of glucose under anaerobic conditions to a suspension of the yeast Saccharomyces cerevisiae causes both a transient hyperpolarization and a transient net efflux of K+ from the cells. Hyperpolarization shows a peak at about 3 min and a net K+ efflux at 4-5 min. An additional transient hyperpolarization and net K+ efflux are found after 60-80 and 100 min, respectively. Addition of 2-deoxyglucose instead of glucose does not lead to hyperpolarization of the cells or K+ efflux. At low pH, neither transient hyperpolarization nor a transient K+ efflux are found. With ethanol as substrate and applying aerobic conditions, both a transient hyperpolarization and a transient K+ efflux are found at pH 7. The fluorescent probe 2-(dimethylaminostyryl)-1-ethylpyridinium appears to be useful for probing changes in the membrane potential of S. cerevisiae. It is hypothesized that the hyperpolarization of the cells is due to opening of K+ channels in the plasma membrane. Accordingly, the hyperpolarization of the cells at pH 7 is almost completely abolished by 1.25 mM K+, whereas the same amount of Na+ does not reduce the hyperpolarization.
van de Mortel
J B
JB
Laboratory of Chemical Cytology, R.C. University, Nijmegen, The Netherlands.
Mulders
D
D
Korthout
H
H
Theuvenet
A P
AP
Borst-Pauwels
G W
GW
D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D003847:Deoxyglucose / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D005456:Fluorescent Dyes; D005947:Glucose / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D009861:Onium Compounds / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D011726:Pyridinium Compounds; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology; D013050:Spectrometry, Fluorescence
D005456:Fluorescent Dyes; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D015221:Potassium Channels; D011726:Pyridinium Compounds; D000431:Ethanol; C025042:2-(dimethylaminostyryl)-1-ethylpyridinium; D003847:Deoxyglucose; D012964:Sodium; D005947:Glucose; D011188:Potassium; C013289:tetraphenylphosphonium