Author/Editor		Lahajnar, Gojmir; Maček, Peter; Zupančič, Ivan
Title		Suppression of red cell diffusional water permeability by lipophilic solutes
Type		članek
Source		Bioelectroch Bioener
Vol. and No.		Letnik 52
Publication year		2000
Volume		str. 179-85
Language		eng
Abstract		The inhibitory effect of a series of neutral lipophilic solutes (methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-amylalcohol, n-hexanol diethylether, nitrobenzene, and pyridine) on the diffusional water permeability ( Pd tot) of bovine erythrocyte membrane at 25 degrees C was studied in comparison to that of p-chloromercuri benzoate (pCMB). Permeability data were obtained by measuring the transmembrane diffusional water exchange time tan exch using an 1H-T2 NMR technique. Maximal inhibition by - 50% of Pd tot was produced by 2 mM pCMB which completely blocked the membrane water channels in 20 min, hence suggesting the channel-to-lipid diffusional water permeability ratio of about 1:1. Furthermore; the maximal inhibitory effect of pCMB in combination with the lipophilic solutes was lower than that of pCMB alone., As pCMB does not interfere with the lipid bilayer, and provided that it blocks the water channels in solute presence as well, this confirms that the solutes induce an increase in the lipid-mediated background water permeability contribution (Pd, lipid) by the formation of aqueous leaks in the membrane hydrophobic barrier. However, faster but less efficient in permeability inhibition than pCMB (either alone or combined with solutes) were the lipophilic solutes alone. Taken together, the results indicate that the lipophilic solutes suppress the membrane total permeability Pd, tot by two opposing effects: a reduction of its channel-mediated part ( Pd channel) to the extent exceeding that of a simultaneous Pd lipid increase. The inhibitory potency of the solutes tested appears to be correlated with their solubility in the membrane medium.
Descriptors		ERYTHROCYTE MEMBRANE CELL MEMBRANE PERMEABILITY WATER DIFFUSION NUCLEAR MAGNETIC RESONANCE CHLOROMERCURIBENZOATES BIOLOGICAL TRANSPORT ALCOHOL, METHYL ALCOHOL, ETHYL ALCOHOL, PROPYL ALCOHOLS, BUTYL ALCOHOLS, HEXYL ETHER, ETHYL NITROBENZENES PYRIDINES