Changes in membrane fluidity induced by tryptophan and its metabolites.
Incorporation of fatty acids into phospholipids as well as cholesterol and phospholipid concentration has been investigated using samples of rat liver homogenate, Krebs-Ringer-phosphate buffer (pH = 7.4), containing 0.3% albumin, fatty acid mixture and glycerol. The addition of kynurenine, kynurenic, xanthurenic, picolinic, and 5-hydroxyindoleacetic acids to incubation medium for phospholipid biosynthesis in vitro induced the elevation of cholesterol/phospholipid ratio, cholesterol concentration in samples, an increase of saturated and a decrease of polyunsaturated fatty acids, especially arachidonic acid incorporation into phospholipids. It allowed us to suggest that these metabolites of tryptophan can decrease the membrane fluidity, depress cell cycle, cell transformation and may stimulate cholesterol precipitation. The addition of tryptophan, 3-hydroxykynurenine, 3-hydroxyanthranilic, quinolinic, nicotinic acids, serotonin together with iproniasid, acetylserotonin, and melatonin to incubation medium for phospholipid biosynthesis in vitro induced an inverse relationship. Tryptophan and above mentioned metabolites decreased cholesterol/phospholipid ratio, cholesterol concentration in samples and incorporation of saturated fatty acids into phospholipids. The incorporation of polyunsaturated fatty acids, especially arachidonic acid increased. It allowed us to suggest that tryptophan and these metabolites, may increase membrane fluidity, stimulate cell cycle, cell transformation and can protect against cholesterol precipitation.
Rudzite
V
V
Latvia Institute of Cardiology, Laboratory of Biochemistry, Riga, Latvia.
Jurika
E
E
Jirgensons
J
J
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000494:pharmacology; D007700:Kinetics; D007736:Kynurenic Acid / Q000494:pharmacology; D007737:Kynurenine / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects* / Q000502:physiology; D008563:Membrane Lipids / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis / Q000378:metabolism; D010848:Picolinic Acids / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014977:Xanthurenates / Q000494:pharmacology
D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; D010848:Picolinic Acids; D014977:Xanthurenates; D007737:Kynurenine; D006897:Hydroxyindoleacetic Acid; C028330:xanthurenic acid; D014364:Tryptophan; D002784:Cholesterol; D007736:Kynurenic Acid; C030614:picolinic acid