chapter  19
7 Pages

Cortisol increases EDHF-mediated relaxations in porcine coronary arteries and up-regulates the expression of cytochrome P450 2C9

Porcine coronary arteries (obtained from the loca l slaughterhouse) were cleaned o f connective tissue and cut into segments ( 3 4 m m i n length). Segments were cultured in M e d i u m 199 (cc pro , Neustadt , Germany) conta in ing p o l y m y x i n B . R ings were incubated wi th Cortisol ( 1 0 - 7 M ) or vehicle for 24 h. Thereafter, rings were mounted i n an organ bath ( F ô h r M e d i c a l Instruments, Seeheim, Germany) for isometric force measurement as described (Bauersachs et al, 1997). R ings were equil ibrated for 30 m i n under a resting tension o f 3 g in oxygenated (95% 0 2 , 5% C 0 2 ) K r e b s - Henseleit solut ion ( p H 7.4, 37 °C) o f the fo l lowing composi t ion: N a C l 118mmol / l , K C I 4 . 7 m m o l / l , M g S 0 4 1 .2mmol/ l , C a C l 2 1 .6mmol/ l , K 2 H P 0 4 1 .2mmol/ l , N a H C 0 3 2 5 m m o l / l , glucose 12mmol / l , and the cycloxygenase inhib i tor diclofenac ( 1 0 " 6 M ) . R ings were repeatedly contracted by K C I ( l O O m M ) un t i l reproducible responses were obtained. Thereafter, the rings were preconstricted wi th the thromboxane mimet ic U46619 ( 1 0 " 8 - 1 0 ~ 7 M ) to about 70% o f the m a x i m a l constr ict ion and the relaxat ion to cumulat ive doses o f b r adyk in in ( 1 0 - 1 0 — 1 0 6 M ) and to sodium nitroprusside ( 1 0 ~ 9 - 1 0 - 6 M ) was assessed w i t h or wi thout p r io r inh ib i t ion o f N O synthase using N^-n i t ro -L-a rg in ine ( L - N A , 3 x 10~ 4 M , 30 min) . F o r the determination o f short-term effects, Cortisol was appl ied to the organ chamber for 30 m i n .