Arachidonic acid increases intracellular calcium in erythrocytes.
Recently, we have measured in erythrocytes a voltage-modulated and dihydropyridine-inhibited calcium influx. Since arachidonic acid and other polyunsaturated fatty acids influence the activities of most ion channels, we studied their effects on the erythrocyte Ca(2+) influx. It was measured on fresh erythrocytes, isolated from healthy donors, using the fluorescent dye Fura 2 as indicator of [Ca(2+)](i). AA (5-50 microM) and EPA (20-30 microM) stimulated a concentration-dependent increase in [Ca(2+)](i), deriving from extracellular calcium (1 mM), without affecting the intra- and extracellular pH and membrane voltage. The Ca(2+) influx rate varied from 0.5 to 3 nM Ca(2+)/s in the presence of AA and from 0.9 to 1.7 nM Ca(2+)/s with EPA. The Ca(2+) influx elicited by AA and EPA was not inhibited by dihydropyridines, while cyclooxygenase inhibitors were effective and PGE1 or PGE2 did not produce any effect. We conclude that AA could activate an erythrocyte voltage-independent Ca(2+) transport via an intermediate product of cyclooxygenase pathway; however, a direct interaction with the membrane lipid-protein cannot be excluded.
Soldati
Laura
L
Department of Sciences and Biomedical Technologies, Milan University, LITA, Via F.lli Cervi 93, Segrate (MI) 20090, Italy. laura.soldati@unimi.it
Lombardi
Cinzia
C
Adamo
Donatella
D
Terranegra
Annalisa
A
Bianchin
Cristiana
C
Bianchi
Giuseppe
G
Vezzoli
Giuseppe
G
D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009543:Nifedipine / Q000494:pharmacology; D019301:Oleic Acid / Q000494:pharmacology; D011453:Prostaglandins / Q000494:pharmacology
D002121:Calcium Channel Blockers; D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; D015117:5,8,11,14-Eicosatetraynoic Acid; D016718:Arachidonic Acid; D019301:Oleic Acid; D015118:Eicosapentaenoic Acid; D009543:Nifedipine; D002118:Calcium