14(R),15(S)-epoxyeicosatrienoic acid (14(R),15(S)-EET) receptor in guinea pig mononuclear cell membranes.
A high affinity binding site for 14(R),15(S)-EET, one of the major cytochrome P-450 metabolites of arachidonic acid (AA) in blood vessels, liver, kidney and urine of patients with pregnancy-induced hypertension, has been identified in a membrane preparation from guinea pig mononuclear (GPM) cells. Using a radioligand assay, binding of 14(R),15(S)-[3H]EET to its receptor site was saturable, specific and reversible. Scatchard analysis of saturation binding studies yielded a dissociation constant (Kd) of 5.7 x 10(-9) M, and maximum number of binding sites (Bmax) of 2.4 pmol/mg membrane protein. The specificity of the binding site was determined by competition studies. 14(S),15(R)-EET and 8,9-EET had a Ki of 6.3 and 8.8 nM, respectively, followed by 12(R)-HETE and LTD4. 12(S)-HETE and 5,6-EET were even less effective as a competitive inhibitor of radioligand and binding with Ki values from 2 to 20 microM. Receptor antagonists for TxA2, LTB4, LTD4 and PAF failed to displace 14(R),15(S)-[3H]EET from its binding site on GPM cell membranes. The results correlate well with the reported biological functions of 14,15-EET. In view of its potent biological activities, 14,15-EET may exert its cellular function through the binding and activation of its stereo-specific cell surface binding sites or receptor.
Department of Physiology and Medicine, New York Medical College, Valhalla 10595.
P Y
PY
Wong
K T
KT
Lin
Y T
YT
Yan
D
D
Ahern
J
J
Iles
S Y
SY
Shen
R K
RK
Bhatt
J R
JR
Falck
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D010529:Peritoneal Cavity / Q000166:cytology; D011956:Receptors, Cell Surface / Q000378:metabolism*
D008563:Membrane Lipids; D011956:Receptors, Cell Surface; D016718:Arachidonic Acid; C046782:14,15-epoxy-5,8,11-eicosatrienoic acid; D003577:Cytochrome P-450 Enzyme System; D015126:8,11,14-Eicosatrienoic Acid