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Increased chemiluminescence of polymorphonuclear leucocytes in dogs with volume overload heart failure
K Prasad1, J Kalra, B Bharadwaj
1Department of Physiology, University of Saskatchewan, Saskatoon, Canada.
Abstract:
Polymorphonuclear leucocyte (PMN) stimulation is known to generate oxygen free radicals. Exogenous oxygen free radicals, generated by xanthine and xanthine oxidase, have been implicated in the decrease of cardiac contractility. It is possible that PMN have increased capacity to release oxygen free radicals in failing heart. It was, therefore, decided to investigate PMN chemiluminescence (oxygen free radicals) from blood in dogs with heart failure due to chronic volume overload. The dogs were divided into two groups: (A) normal, six dogs; (B) dogs with mitral insufficiency (MI) of 6-9 months' duration, six dogs. Haemodynamic parameters were recorded to assess cardiac failure. Mixed venous blood was collected to measure PMN chemiluminescence. Stimulation of PMN was initiated by addition of opsonized zymosan and chemiluminescence was monitored using a luminometer. The haemodynamic parameters in dogs with MI showed that these dogs had left ventricular failure. The peak chemiluminescent activity of PMN in blood of dogs with left ventricular failure was approximately four times that in the blood from normal dogs. This increase in chemiluminescence reflects an increase in the generation of oxygen free radicals from PMN in dogs with chronic heart failure. The decrease in the myocardial contractility in cardiac failure might be due to an increase in the oxygen free radicals produced by the PMN.
Insights
Polymorphonuclear leucocytes (PMN) from dogs with heart failure generate significantly more oxygen free radicals. This increased radical production may contribute to reduced myocardial contractility in heart failure.
Area of Science:
- Cardiology
- Immunology
- Biochemistry
Background:
- Polymorphonuclear leucocytes (PMN) generate oxygen free radicals upon stimulation.
- Exogenous oxygen free radicals are linked to decreased cardiac contractility.
- PMN may increase oxygen free radical release in failing hearts.
Purpose of the Study:
- To investigate PMN chemiluminescence, an indicator of oxygen free radicals, in dogs with heart failure.
- To determine if PMN from failing hearts produce more oxygen free radicals.
Main Methods:
- Dogs with chronic mitral insufficiency (heart failure) and normal dogs were studied.
- Haemodynamic parameters were assessed to confirm cardiac failure.
- PMN chemiluminescence was measured in mixed venous blood after stimulation with opsonized zymosan.
Main Results:
- Dogs with mitral insufficiency exhibited left ventricular failure.
- Peak PMN chemiluminescent activity was approximately four times higher in dogs with heart failure compared to normal dogs.
- This indicates increased oxygen free radical generation by PMN in chronic heart failure.
Conclusions:
- PMN in dogs with chronic heart failure show an elevated capacity for oxygen free radical production.
- Increased oxygen free radicals from PMN may be a contributing factor to decreased myocardial contractility in heart failure.