Vascular smooth muscle cell heme oxygenases generate guanylyl cyclase-stimulatory carbon monoxide.
BACKGROUND
Carbon monoxide (CO), like nitric oxide (NO), stimulates soluble guanylyl cyclase and thereby raises intracellular levels of cGMP. We examined the endogenous capacity of vascular smooth muscle cells (SMCs) to produce CO from heme through the activity of heme oxygenases.


RESULTS
Cultured SMCs from rat aorta (RASMCs) expressed immunoreactive inducible heme oxygenase-1 (HO-1) and constitutive HO-2. Treatment of RASMCs with hemin and sodium arsenite, which are inducers of HO-1, stimulated RASMC cGMP without stimulating nitrite release or inducible NO synthase expression, and the induced elevations of cGMP were not inhibited by the NO synthase inhibitor NG-methyl-L-arginine. Induced CO from RASMCs likewise caused elevation of cGMP levels in platelets coincubated with the vascular cells. Zinc protoporphyrin IX, an inhibitor of HO, reversed the inducible increases in platelet cGMP.


CONCLUSIONS
These results indicate that vascular SMCs have both constitutive and inducible HO activity, and they respond to specific stimuli to generate guanylyl cyclase-stimulatory CO in the same SMCs and in coincubated platelets.
Christodoulides
N
N
Houston (Tex) Veterans Affairs Medical Center 77030, USA.
Durante
W
W
Kroll
M H
MH
Schafer
A I
AI
D000818:Animals; D001011:Aorta / Q000378:metabolism; D018053:Arsenites / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D002248:Carbon Monoxide / Q000378:metabolism*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D006162:Guanylate Cyclase / Q000096:biosynthesis* / Q000378:metabolism; D006418:Heme / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000032:analysis*; D006427:Hemin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D051381:Rats; D017670:Sodium Compounds / Q000494:pharmacology
D018053:Arsenites; D017077:Culture Media, Conditioned; D017670:Sodium Compounds; D006418:Heme; C017947:sodium arsenite; D006427:Hemin; D002248:Carbon Monoxide; D006419:Heme Oxygenase (Decyclizing); D006162:Guanylate Cyclase