Key result
Intracoronary nNOS inhibition with SMTC reduces basal coronary blood flow by ~34%.
Why the study?
The distinct local roles of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS) in regulating human coronary vascular tone in vivo were unclear.
Does nNOS-selective inhibition with SMTC reduce basal coronary blood flow and affect flow-mediated dilatation in humans?
Population
Patients with angiographically normal coronary arteries and healthy volunteers
Comparison
nNOS-selective inhibitor S-methyl-L-thiocitrulline vs nonselective NOS inhibitor N(G)-monomethyl-L-arginine
Design
In vivo infusion study in human coronary and forearm circulation
Authors
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Should not change practice; extends evidence for distinct nNOS versus eNOS roles in coronary tone.
Does nNOS-selective inhibition with SMTC reduce basal coronary blood flow and affect flow-mediated dilatation in humans?
p-value: p=<0.01
This study demonstrates that neuronal NO synthase (nNOS) regulates basal blood flow in the human coronary vascular bed, whereas endothelial NOS (eNOS) mediates stimulated vasodilatation.
Seddon et al. (2009) studied Angiographically normal coronary arteries. S-methyl-L-thiocitrulline (SMTC) vs. N(G)-monomethyl-L-arginine (L-NMMA) was evaluated on Reduction in basal coronary blood flow (p=<0.01). Intracoronary infusion of the nNOS-selective inhibitor SMTC reduced basal coronary blood flow by 34.1% (P<0.01), indicating that nNOS regulates basal coronary vascular tone in vivo.
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