Cytochrome P450 2C expression and EDHF-mediated relaxation in porcine coronary arteries is increased by cortisol.
OBJECTIVE
In addition to nitric oxide (NO) and prostacyclin, endothelium-dependent dilation is mediated by the endothelium-derived hyperpolarizing factor (EDHF) which, in the coronary circulation, has been characterised as a metabolite of arachidonic acid synthesised by an cytochrome P450 (CYP) epoxygenase homologous to CYP 2C8/9. As the promotor regions of CYP 2C8 and 2C9 contain consensus sequences for glucocorticoid response elements, we determined the effect of cortisol on EDHF-mediated relaxations as well as on the expression of CYP 2C in isolated segments of porcine coronary artery.


RESULTS
Bradykinin-induced NO-mediated relaxation of KCl-constricted arterial rings was slightly attenuated following exposure to cortisol. However, EDHF-mediated relaxations of U46619-constricted arterial rings assessed in the presence of the cyclo-oxygenase inhibitor diclofenac and the NO synthase inhibitor N(omega)nitro-L-arginine (0.3 mM), were significantly enhanced (maximum relaxation: 66+/-7%, P<0.05 vs. control rings: 36+/-8%). Cortisol treatment (0.1 microM, 24 h) did not affect the endothelium-independent relaxation elicited by sodium nitroprusside and acute incubation with cortisol (0.1 microM, 30 min) did not alter either NO- or EDHF-mediated responses. The expression of CYP 2C (quantified by RT-PCR, Western blot analysis and confocal microscopy) was enhanced in porcine coronary endothelial cells following incubation with cortisol for 18-24 h.


CONCLUSIONS
These results demonstrate the concomitant upregulation of EDHF-mediated relaxations and CYP 2C expression by long-term treatment with cortisol. These observations support the concept that an epoxygenase homologous to CYP 2C8/9 plays a crucial role in the generation of EDHF-mediated responses in the coronary endothelium.
Bauersachs
J
J
Medizinische Klinik der Julius-Maximilians-Universität Würzburg, Würzburg, Germany. j.bauersachs@medizin.uni-wuerzburg.de
Christ
M
M
Ertl
G
G
Michaelis
U R
UR
Fisslthaler
B
B
Busse
R
R
Fleming
I
I
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001685:Biological Factors / Q000494:pharmacology*; D003331:Coronary Vessels / Q000201:enzymology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006854:Hydrocortisone / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009924:Organ Culture Techniques; D039181:Steroid 16-alpha-Hydroxylase; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013552:Swine; D014664:Vasodilation / Q000187:drug effects*
D001685:Biological Factors; C067410:endothelium-dependent hyperpolarization factor; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; D039181:Steroid 16-alpha-Hydroxylase; D006854:Hydrocortisone