Heme oxygenase activity in the adult rat aorta and liver as measured by carbon monoxide formation.
Rat aorta was homogenized and the 13000 x g supernatant fraction was tested for heme oxygenase (HO) activity by using a sensitive gas chromatographic method to measure carbon monoxide (CO), one of the products of the HO reaction. The rate of NADPH-dependent CO formation, an index of HO activity, was 1.41 +/- 0.40 nmol CO.mg(-1)protein. h(-1) in the rat aorta supernatant fraction and 2.05 +/- 0.55 nmol CO.mg(-1) protein.h(-1) in the rat liver 13000 x g supernatant fraction, a tissue known to contain HO activity. Chromium mesoporphyrin (0.05 mM), an inhibitor of rat liver HO, significantly decreased HO activity by 26% in the aorta supernatant fraction and 50% in the liver supernatant fraction. On the basis of the results of this study, which demonstrated HO-catalyzed CO formation in aortic tissue, and previous observations that CO relaxes vascular smooth muscle, we suggest that a physiological role for CO in vascular smooth muscle relaxation should be further investigated.
Cook
M N
MN
Department of Pharmacology and Toxicology, Faculty of Medicine, Queen's University, Kingston, ON, Canada.
Nakatsu
K
K
Marks
G S
GS
McLaughlin
B E
BE
Vreman
H J
HJ
Stevenson
D K
DK
Brien
J F
JF
D000818:Animals; D001011:Aorta / Q000201:enzymology*; D002248:Carbon Monoxide / Q000378:metabolism*; D002849:Chromatography, Gas; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology*; D008297:Male; D008652:Mesoporphyrins / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D009249:NADP / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D008652:Mesoporphyrins; C031468:mesoporphyrin IX; D009249:NADP; D002248:Carbon Monoxide; D006419:Heme Oxygenase (Decyclizing)