Biomaterial Database

Nitric oxide involvement in hypoxic dilation of pial arteries in the cat. 1996

N Ishimura, and K Kitaguchi, and K Tatsumi, and H Furuya

Department of Anesthesiology, Nara Medical University, Japan.

BACKGROUND The reactivity of cerebral arteries to different stimuli varies according to vessel size. Whether nitric oxide mediates hypoxic vasodilation is controversial. The authors considered this question by measuring the diameter of pial arteries and arterioles with or without exposure to the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME). METHODS The cranial window technique, combined with microscopic video recording, was used in an experiment involving 20 cats anesthetized with fentanyl and midazolam. The diameters of pial arteries and arterioles were measured under the following conditions: (1) normoxia (PaO2 > 100 mmHg); (2) hypoxia (PaO2 < 45 mmHg); (3) normoxia with L-NAME infusion; and (4) hypoxia with L-NAME infusion. Changes in vessel diameter were analyzed with respect to artery size. RESULTS Under hypoxic conditions, arteries and arterioles smaller than 200 microns were dilated significantly (P < 0.05). In arterioles smaller than 200 microns, L-NAME attenuated this hypoxic vasodilation (P < 0.05). In contrast, under normoxic conditions, L-NAME caused significant vasoconstriction in arteries larger than 100 microns but not in arteries smaller than 100 microns. CONCLUSIONS Arteries and arterioles smaller than 200 microns are dilated by hypoxia, and nitric oxide contributes to this process. Nitric oxide synthesis may also be related to the regulation of resting vascular tone in arteries larger than 100 microns.

UI	MeSH Term	Description	Entries
D009569	Nitric Oxide	A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.	Endogenous Nitrate Vasodilator,Mononitrogen Monoxide,Nitric Oxide, Endothelium-Derived,Nitrogen Monoxide,Endothelium-Derived Nitric Oxide,Monoxide, Mononitrogen,Monoxide, Nitrogen,Nitrate Vasodilator, Endogenous,Nitric Oxide, Endothelium Derived,Oxide, Nitric,Vasodilator, Endogenous Nitrate
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D002536	Cerebral Arteries	The arterial blood vessels supplying the CEREBRUM.	Arteries, Cerebral,Artery, Cerebral,Cerebral Artery
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D006439	Hemodynamics	The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.	Hemodynamic
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000860	Hypoxia	Sub-optimal OXYGEN levels in the ambient air of living organisms.	Anoxia,Oxygen Deficiency,Anoxemia,Deficiency, Oxygen,Hypoxemia,Deficiencies, Oxygen,Oxygen Deficiencies
D014664	Vasodilation	The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.	Vasodilatation,Vasorelaxation,Vascular Endothelium-Dependent Relaxation,Endothelium-Dependent Relaxation, Vascular,Relaxation, Vascular Endothelium-Dependent,Vascular Endothelium Dependent Relaxation
D019001	Nitric Oxide Synthase	An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE.	NO Synthase,Nitric-Oxide Synthase,Nitric-Oxide Synthetase,Nitric Oxide Synthetase,Oxide Synthase, Nitric,Synthase, Nitric Oxide
D019331	NG-Nitroarginine Methyl Ester	A non-selective inhibitor of nitric oxide synthase. It has been used experimentally to induce hypertension.	L-NAME,N omega-Nitro-L-arginine Methyl Ester,NG-Nitro-L-Arginine Methyl Ester,N(G)-Nitro-L-arginine Methyl Ester,N(G)-Nitroarginine Methyl Ester,N(omega)-Nitro-L-arginine Methyl Ester,NG-Nitroarginine Methyl Ester, D-Orn-Isomer,NG-Nitroarginine Methyl Ester, L-Orn-Isomer, Monohydrochloride,Methyl Ester, NG-Nitro-L-Arginine,Methyl Ester, NG-Nitroarginine,N omega Nitro L arginine Methyl Ester,NG Nitro L Arginine Methyl Ester,NG Nitroarginine Methyl Ester,NG Nitroarginine Methyl Ester, D Orn Isomer