Effect of fatty acids on plasma membrane lipid dynamics and cation permeability in neuroblastoma cells

Abstract

In this study the effects of experimental modifications of plasma membrane lipid lateral mobility on the electrical membrane properties and cation transport of mouse neuroblastoma cells, clone Neuro-2A, have been studied. Short-term supplementation of a chemically defined growth medium with oleic acid or linoleic acid resulted in an increase in the lateral mobility of lipids as inferred from fluorescence recovery after photobleaching of the lipid probe 3,3'-dioctadecylindocarbocyanide iodide. These changes were accompanied by a marked depolarization of the membrane potential from -51 mV to -36 mV, 1.5 h after addition, followed by a slow repolarization. Tracer flux studies, using S6Rb÷ as a radioactive tracer for K ÷ , demonstrated that the depolarization was not caused by changes in (Na ÷ + K + )-ATPase-mediated K + influx or in the transmembrane K ÷ gradient. The permeability ratio (PNa/PK), determined from electrophysiological measurements, however, increased from 0.10 to 0.27 upon supplementation with oleic acid or linoleic acid. This transient rise of PN,/Px Was shown by 24Na+ and S6Rb+ flux measurements to be due to both an increase of the Na + permeability and a decrease of the K ÷ permeability. None of these effects occurred upon supplementation of the growth medium with stearic acid.

Lateral mobility of plasma membrane lipids in dividing Xenopus eggs

“…Laser mode and radius were calibrated by scanning a fluorescent glass fiber through the laser beam with known velocity (L. G. J. Tertoolen, unpublished). The fluorescence intensity was measured by a single photon counting system, as described earlier (Boonstra et al, 1982). In the illuminated region 40-60% of the fluorescence intensity was bleached by a brief (20-60 m/set), approximately lOOO-to 2500-fold increase in laser intensity.…”

Lateral mobility of plasma membrane lipids in Xenopus eggs: Regional differences related to animal/vegetal polarity become extreme upon fertilization

“…Laser mode and radius were calibrated by scanning a fluorescent glass fiber through the laser beam with known velocity (L. G. J. Tertoolen, unpublished). The fluorescence intensity was measured by a single photon counting system equipped with a photomultiplier (EM1 9863/.100, EMI, Hayes Middlesex, U. K.) and an ORTEC 9302 amplifier-discriminator (ORTEC Inc., Oak Ridge, TN, USA) as described by Boonstra et al (1982). In the illuminated region, 40-60s of the fluorescence intensity was bleached by a short (20-60 msec) approximately a lOOO-to 2500-fold increase in laser intensity.…”

Regulation of Voltage-Dependent Channel Function

“…The dependence In the case of the poikilotherm Aplvsia's neurons of lipid diffusibility upon culture conditions has (both dissociated and cultured), we have found D previously been reported for mammalian cells for NBD-C 6 -PC to be independent of temperature [42,52,53]. from 4'C to 25°C.…”