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May 1, 1996AJP Heart and Circulatory Physiology

Nitric oxide does not modulate myocardial contractility acutely in in situ canine hearts

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Authors

GCGeorge J. CrystalIllinois CollegeJGJuozas GureviciusIllinois College

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Implication

In vivo animal study reveals that nitric oxide does not acutely alter myocardial contractility or oxygen demand in canines, suggesting it lacks direct cardiac inotropic regulation.

Key Points

  • To determine whether nitric oxide acutely modulates myocardial contractility and oxygen consumption in vivo in canine hearts.
  • Perfused the left anterior descending coronary artery of 28 anesthetized, open-chest dogs under conditions of constant coronary perfusion pressure (n = 23) or constant coronary blood flow (n = 5).
  • Assessed myocardial contractility (segmental shortening via ultrasonic crystals) and calculated myocardial oxygen consumption during intracoronary infusions of nitric oxide donors (sodium nitroprusside, nitroglycerin) or an endogenous stimulator (acetylcholine).
  • Evaluated responses following basal nitric oxide synthase inhibition with L-NAME or L-NMMA, using intracoronary isoflurane as a negative inotropic control.
  • With constant perfusion pressure, sodium nitroprusside, nitroglycerin, and acetylcholine increased coronary blood flow by 177%, 28%, and 280%, respectively, but produced no changes in segmental shortening or myocardial oxygen consumption.
  • Inhibition of nitric oxide synthase using L-NAME or L-NMMA did not significantly alter segmental shortening, myocardial oxygen consumption, or coronary blood flow.
  • With constant coronary blood flow, sodium nitroprusside and acetylcholine decreased perfusion pressure without affecting segmental shortening, whereas isoflurane confirmed responsiveness by reducing segmental shortening by 38% and oxygen consumption by 42%.

Cite This Study

Crystal et al. (1996) studied this question.

synapsesocial.com/papers/6a80e2fe407ce5842fa8a5a5https://doi.org/10.1152/ajpheart.1996.270.5.h1568
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Lack of role for nitric oxide in cholinergic modulation of myocardial contractility in vivo2001 · 13 citations
  2. 2A study on the effects of endogenous nitric oxide on coronary blood flow, myocardial oxygen extraction and cardiac contractility1999 · 11 citations
  3. 3Inhibition of Nitric Oxide Synthesis Reduces Coronary Blood Flow Response But Does Not Increase Cardiac Contractile Response to β-Adrenergic Stimulation in Normal Dogs1996 · 15 citations
  4. 4Nitric oxide modulates cardiac contractility and oxygen consumption without changing contractile efficiency1998 · 36 citations
  5. 5Endogenous nitric oxide modulates myocardial oxygen consumption in canine right ventricle2001 · 12 citations