PMID: 7544690Jun 1, 1995Paper

Effects of nitric oxide synthase inhibition on myocardial capillary permeability and reactive hyperaemic response

Cardiovascular Research
P R Hansen, S Haunsø

Abstract

The aim was to examine the role of nitric oxide (NO) in the myocardial microcirculation. Open chest anaesthetised dogs received intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA; 0.5 mg.kg-1 over 30 min). Myocardial microvascular extraction fraction of a small hydrophilic solute (technetium 99m labelled diethylenetriaminepenta-acetate [99mTc-DTPA]), and the regional myocardial plasma flow rate, were determined by the single injection, residue detection method, and the capillary permeability-surface area product was calculated. The tone in intramyocardial resistance vessels was assessed by the local 133Xe washout method during baseline conditions, in response to intracoronary acetylcholine, and during peak reactive hyperaemia after 10 s or 30 s of myocardial ischaemia, respectively. In eight open chest dogs, L-NMMA attenuated the increase in myocardial plasma flow rate in response to intracoronary acetylcholine by 32(SEM 7)%, but failed to alter baseline myocardial plasma flow rate significantly, as determined by the local 133Xe washout method. L-NMMA did not influence myocardial microvascular permeability to 99mTc-DTPA. However, intracoronary L-NMMA decreased the peak reactive hyperaemic myocardial plasma flow rate aft...Continue Reading

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