Predictors of inotropic and chronotropic effects of NG-monomethyl-L-arginine

Eur J Clin Invest. 2009 Apr;39(4):273-9. doi: 10.1111/j.1365-2362.2009.02097.x.

Abstract

Background: The haemodynamic effects of intravenous infusion of the non-selective nitric oxide synthase (NOS) L-omega monomethyl arginine (L-NMMA) have previously been characterized in humans. Its effect of reducing cardiac index (CI) is an important reason for the increase in mortality in patients with septic shock receiving L-NMMA in a pivotal outcome trial for this indication. The mechanism for the reduction in CI however, is uncertain.

Methods: In this study, we investigated the haemodynamic and arterial stiffness response to a bolus intravenous infusion of L-NMMA (3 mg kg(-1) over 5 min) in 26 healthy human volunteers to clarify the likely cause of L-NMMA induced negative inotropic and chronotropic effects. Digital photoplethysmography (MicroMedical Pulse Trace) was used to derive two measures of arterial stiffness: stiffness index, a measure of large arterial stiffness, and reflection index (RI), a measure of small- to medium-sized arterial stiffness. Haemodynamic measurements of systolic blood pressure, diastolic blood pressure, heart rate, systemic vascular resistance index (SVRI), stroke index and CI were made using a bioimpedance monitor (BioZ Cardiodynamics).

Results: We found that changes in CI during L-NMMA are closely related to changes in RI and SVRI.

Conclusion: The negative inotropic effect of L-NMMA may be a result of an increase in coronary vascular resistance and a resultant decrease in myocardial perfusion. The reduction in CI may also result from a direct reduction of the normal positive inotropic effect of NO by L-NMMA which is closely correlated with its effects on SVRI.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arteries / drug effects*
  • Blood Flow Velocity / drug effects
  • Enzyme Inhibitors / pharmacology*
  • Female
  • Heart Rate / drug effects*
  • Hemodynamics / drug effects*
  • Humans
  • Male
  • Myocardial Contraction / drug effects*
  • Nitric Oxide Synthase / pharmacology
  • Regression Analysis
  • Young Adult
  • omega-N-Methylarginine / pharmacology*

Substances

  • Enzyme Inhibitors
  • omega-N-Methylarginine
  • Nitric Oxide Synthase