ISSN:
1432-1424
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The permeation of various cations and biogenic amines across artificial lipid membranes (bilayer membranes) was investigated by means of electrical conductivity measurements and fluorescence spectroscopy. Their permeability properties were modified by doping them with five different carboxylic ionophores. The induced permeability changes were correlated with some biological activities of the ionophores. Four out of five ionophores increased the permeability of doped membranes for Li+, Na+, K+, Mg2+ and Ca2+. Two of them showed a preference for K+ whereas one (X-537A) increased the membrane permeability for K+ as well as for Ca2+. It was also found that the ionophores increased the permeability for serotonin, dopamine, norepinephrine and epinephrine. No direct coupling was found between the facilitated ion permeation and the permeation of biogenic amines induced by the ionophores. The measurements can be qualitatively explained by assuming that the permeation of biogenic amines is competitively inhibited by cations. It appears that one biogenic amine molecule forms a complex with one ionophore molecule, the complex acting as a carrier for biogenic amines. All ionophores investigated increased the bilayer permeability considerably for some biogenic amines. (A preference up to 420∶1 for serotonin over epinephrine was measured for one specific ionophore.) There was no correlation between thein vitro antibacterial activity (against bacillus E and bacillus TA) of the ionophores and their potency to change the ion permeability of doped membranes. The correlation found between the ionophore-induced permeation of biogenic amines through membranes and their antibacterial activity is probably without biological meaning. However, a rather good correlation was found between cardiac sympathetic effects of the ionophores and their ability to facilitate permeation of norepinephrine through artificial membranes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01870117
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