Abstract |
The endothelial cell plays an important role in the local control of vascular smooth muscle tone. Portal hypertension is accompanied by systemic vasodilatation and a decreased response to vasoconstrictors, changes especially evident in the superior mesenteric arterial bed. To evaluate a possible effect of the locally released endothelium-derived relaxing factor nitric oxide (NO), we tested the effect of NO blockade in in vitro perfused superior mesenteric arterial beds of normal ( sham) and portal hypertensive (PVL) rats, induced by partial portal vein ligation. A significant (n = 7/group; P = 0.02) hyporeactivity to the vasoconstrictive properties of the alpha- adrenoceptor agonist methoxamine (3 x 10(-6) to 3 x 10(-4) M) was prevented by blocking NO formation in PVL compared with sham rats, using the stereospecific biosynthesis antagonist N omega-nitro-L-arginine (10(-4) M, n = 7/group; NS for all methoxamine concentrations tested). This effect was reversed by the NO precursor L-arginine (10(-3) M, n = 5/group). In conclusion, these in vitro results in mesenteric vessels demonstrate that 1) portal hypertension is accompanied by a hyporeactivity to the vasopressor methoxamine and 2) locally released NO in this preparation is responsible for the decreased vasoconstrictive response.
|
Authors | C C Sieber, R J Groszmann |
Journal | The American journal of physiology
(Am J Physiol)
Vol. 262
Issue 6 Pt 1
Pg. G996-1001
(Jun 1992)
ISSN: 0002-9513 [Print] United States |
PMID | 1616049
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)
|
Chemical References |
- Nitroprusside
- Nitroarginine
- Nitric Oxide
- Arginine
- Methoxamine
- Acetylcholine
|
Topics |
- Acetylcholine
(pharmacology)
- Animals
- Arginine
(analogs & derivatives, pharmacology)
- Dose-Response Relationship, Drug
- Hypertension, Portal
(physiopathology)
- Kinetics
- Male
- Mesenteric Arteries
(drug effects, physiology, physiopathology)
- Methoxamine
(pharmacology)
- Muscle, Smooth, Vascular
(drug effects, physiology, physiopathology)
- Nitric Oxide
(metabolism)
- Nitroarginine
- Nitroprusside
(pharmacology)
- Perfusion
- Rats
- Rats, Inbred Strains
|