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Role of heme oxygenase/carbon monoxide pathway on the vascular response to noradrenaline in portal hypertensive rats
Author(s) -
Erario MA,
Gonzales S,
Romay S,
Eizayaga FX,
Castro JL,
Lemberg A,
Tomaro ML
Publication year - 2005
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2005.04171.x
Subject(s) - heme oxygenase , portal hypertension , chemistry , medicine , heme , nitric oxide , nitric oxide synthase , endocrinology , splanchnic , portal venous pressure , mean arterial pressure , zinc protoporphyrin , hyperdynamic circulation , blood pressure , hemodynamics , biochemistry , cirrhosis , enzyme , heart rate
SUMMARY 1. Portal hypertension (PH), a major syndrome in cirrhosis, producing hyperdynamic splanchnic circulation and hyperaemia. In order to elucidate the contribution of heme oxygenase to the vascular hyporeactivity, we assessed the activity of heme oxygenase‐1 (HO‐1), measured the in vivo pressure response to noradrenaline (NA) and investigated the effects of blocking the carbon monoxide (CO) and nitric oxide (NO) pathways in a prehepatic model of PH in rats. 2. Portal hypertension was induced by partial portal vein ligation (PPVL). Noradrenaline was injected intravenously. Liver, spleen and mesentery homogenates were prepared for measurement of HO‐1 activity and expression. Four groups of rats were used: (i) a sham group; (ii) a PPVL group; (iii) a sham group pretreated with Zn‐protoporphyrin IX (ZnPPIX); and (iv) a PPVL group pretreated with ZnPPIX. Each group was studied before and after treatment with the NO synthase inhibitor N G ‐nitro‐ l ‐arginine methyl ester ( l ‐NAME). 3. For basal pressures and the pressure response to NA, inhibition of CO and NO pathways by ZnPPIX and l ‐NAME, respectively, produced an increase in mean arterial pressure (MAP) in sham‐operated and in PH rats. Similarly, when both inhibitors were used together in either sham or PPVL rats, a greater increase in MAP was observed. 4. These results, together with the increased HO‐1 activity and expression only in the PH group, have led us to suggest that the heme oxygenase/CO pathway is involved in the vascular response to NA in PH rats.