PT  - JOURNAL ARTICLE
AU  - Richard J. Hendrickson
AU  - Paul A. Cahill
AU  - James V. Sitzmann
AU  - Eileen M. Redmond
TI  - Ethanol Enhances Basal and Flow-Stimulated Nitric Oxide Synthase Activity In Vitro by Activating an Inhibitory Guanine Nucleotide Binding Protein
DP  - 1999 Jun 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1293--1300
VI  - 289
IP  - 3
4099  - http://jpet.aspetjournals.org/content/289/3/1293.short
4100  - http://jpet.aspetjournals.org/content/289/3/1293.full
SO  - J Pharmacol Exp Ther1999 Jun 01; 289
AB  - The aim of this study was to determine the effect of ethanol on endothelial nitric oxide synthase (eNOS), the enzyme responsible for the production of the important vasoactive agent nitric oxide. The effect of ethanol (0.8–160 mM) on both basal and flow-stimulated eNOS activity was determined using cultured bovine aortic endothelial cells (EC). In “static” EC ethanol dose-dependently increased basal eNOS activity with a maximum response (∼2.0-fold increase) achieved at 40 mM in the absence of any effect on cell viability or nitric oxide synthase protein expression. Pertussis toxin (PTX) pretreatment significantly inhibited the ethanol-induced increase in basal eNOS activity. EC exposed to steady laminar flow exhibited a flow- and time-dependent increase in eNOS activity. Ethanol significantly enhanced the laminar flow-induced eNOS response from 0.62 ± 0.1 to 1.06 ± 0.06 pmol [14C]citrulline/mg/min, a response that was inhibited by PTX. PTX-catalyzed ribosylation of Giα substrates, an index of G-protein functional activity, was increased in laminar flow-exposed EC compared with static controls and was further enhanced by ethanol treatment. Likewise, EC exposed to low (∼0.5 dynes/cm2) and high (∼12 dynes/cm2) pulsatile flow demonstrated increased eNOS activity, an effect that was associated with increased PTX-catalyzed ribosylation of Giα substrates. Ethanol enhanced the low flow response in a PTX-sensitive manner. These data demonstrate a stimulatory effect of ethanol on basal and flow-stimulated eNOS activity, mediated in part by a mechanism involving a PTX-sensitive G protein. The American Society for Pharmacology and Experimental Therapeutics