Tetrahydrobiopterin, a cofactor for NOS, improves endothelial dysfunction during chronic alcohol consumption.
We sought to investigate mechanisms that may account for impaired nitric oxide synthase (NOS)-dependent dilatation of cerebral arterioles during alcohol consumption. Our goals were to examine 1) the effect of exogenous application of a cofactor for NOS, i.e., tetrahydrobiopterin (BH4) on the reactivity of pial arterioles during alcohol consumption; and 2) endothelial NOS (eNOS) protein in nonalcohol-fed and alcohol-fed rats. Sprague-Dawley rats were fed liquid diets with or without alcohol for 2-3 mo. We measured in vivo diameter of pial arterioles in response to NOS-dependent agonists (ACh and ADP) and a NOS-independent agonist (nitroglycerin) before and during application of BH4. Blood vessels were then harvested for Western blot analysis of eNOS protein. In nonalcohol-fed rats, ACh and ADP produced vasodilatation, which was impaired in alcohol-fed rats. Vasodilatation to nitroglycerin was similar in both groups of rats. Application of BH4 did not alter vasodilatation in nonalcohol-fed rats but improved impaired vasodilatation in alcohol-fed rats. Also, eNOS protein in cerebral cortex microvessels, the basilar artery, and aorta was not different between nonalcohol-fed and alcohol-fed rats. Thus impaired NOS-dependent vasodilatation during alcohol consumption does not appear to be related to an alteration in eNOS protein but may be related to a deficiency and/or alteration in the utilization of BH4.
Sun
H
H
Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha, Nebraska 68198-4575, USA.
Patel
K P
KP
Mayhan
W G
WG
D000437:Alcoholism / Q000188:drug therapy / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015153:Blotting, Western; D001835:Body Weight; D002536:Cerebral Arteries / Q000187:drug effects / Q000201:enzymology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010841:Pia Mater / Q000098:blood supply; D051381:Rats; D017207:Rats, Sprague-Dawley; D020521:Stroke / Q000188:drug therapy / Q000378:metabolism
D000975:Antioxidants; D001708:Biopterins; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; C003402:sapropterin