Effect of fatty acids on [3H]ouabain binding to cerebromicrovascular (Na+ + K+)-ATPase.
The effects of short- and long-chain fatty acids on the cerebromicrovascular (Na+ + K+)-ATPase were investigated using specific [3H]ouabain binding to the enzyme. Specific binding increased linearly with total microvessel protein (37-110 micrograms) and was time-dependent with maximum binding obtained by 10 min. Arachidonic acid, but not palmitic acid, stimulated [3H]ouabain binding in a dose-dependent manner, with a 105% increase over basal levels at 100 microM arachidonic acid. Preincubation of the microvessels with arachidonic acid did not alter the stimulation observed. 4-Pentenoic acid stimulated [3H]ouabain binding only at high concentrations (10 mM). Scatchard analysis of [3H]ouabain binding to untreated microvessels yielded a single class of "high-affinity" binding sites with an apparent binding affinity (KD) of 64.7 +/- 2.0 nM and a binding capacity (Bmax) of 10.1 +/- 1.5 pmol/mg protein. In the presence of 100 microM arachidonic acid, a monophasic Scatchard plot also was obtained, but the KD significantly decreased to 51.9 +/- 2.7 nM (p less than 0.01), whereas the Bmax remained virtually unchanged (12.5 +/- 1.2 pmol/mg protein). The stimulation of [3H]ouabain binding in the presence of arachidonic acid was potentiated by 4-pentenoic acid, but not by indomethacin or eicosatetraynoic acid. These data suggest that long-chain polyunsaturated fatty acids may be involved in the regulation of blood-brain barrier (Na+ + K+)-ATPase and may play a role in the cerebral dysfunction associated with diseases in which plasma levels of nonesterified fatty acids are elevated.
Caspers
M L
ML
Department of Chemistry, University of Detroit, MI 48221-9987.
Grammas
P
P
D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001921:Brain / Q000098:blood supply*; D004357:Drug Synergism; D005227:Fatty Acids / Q000494:pharmacology*; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000201:enzymology*; D010042:Ouabain / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D001095:Arachidonic Acids; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D010169:Palmitic Acids; D015117:5,8,11,14-Eicosatetraynoic Acid; D016718:Arachidonic Acid; D019308:Palmitic Acid; D010042:Ouabain; C009785:4-pentenoic acid; D000254:Sodium-Potassium-Exchanging ATPase; D007213:Indomethacin