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Circulating endothelin in acute ischaemic syndromes
S G Ray1, J J McMurray, J J Morton
1Department of Cardiology, Western Infirmary, Glasgow, UK.
Insights
Plasma endothelin levels are elevated in chronic heart failure and after acute myocardial infarction, but not in angina. Following myocardial infarction, endothelin rises while atrial natriuretic factor decreases, suggesting a complex role in ischemic heart disease.
Area of Science:
- Cardiovascular Medicine
- Endocrinology
- Nephrology
Background:
- Endothelin, a potent vasoconstrictor, may contribute to acute myocardial ischemia pathogenesis.
- Atrial natriuretic factor acts as an endogenous antagonist to endothelin.
- Investigating circulating endothelin patterns in ischemic heart disease is crucial.
Purpose of the Study:
- To determine the pattern and significance of circulating endothelin in ischemic heart disease.
- To compare endothelin concentrations in controls and patients with stable angina, unstable angina, acute myocardial infarction, and chronic heart failure.
- To examine the relationship between endothelin and atrial natriuretic factor post-myocardial infarction.
Main Methods:
- Studied 18 acute myocardial infarction, 10 unstable angina, 10 stable angina, 12 chronic cardiac failure patients, and 10 controls.
- Measured venous plasma endothelin concentrations using radioimmunoassay.
- Simultaneously measured endothelin and atrial natriuretic factor in acute myocardial infarction patients at set intervals.
Main Results:
- Elevated mean endothelin concentrations were observed in chronic heart failure (13.83 fmol/ml) and acute myocardial infarction (peaking at 11.88 fmol/ml at 4 hours).
- Endothelin levels were not significantly different in stable (6.56 fmol/ml) or unstable angina (6.41 fmol/ml) compared to controls (5.72 fmol/ml).
- In acute myocardial infarction, atrial natriuretic factor levels were low (8.4 pg/ml at 1 hour) when endothelin was high.
Conclusions:
- Plasma endothelin is elevated in chronic heart failure and post-acute myocardial infarction, but not in stable or unstable angina.
- Post-myocardial infarction, elevated endothelin coincides with reduced atrial natriuretic factor.
- Further research is needed to elucidate endothelin's role in acute myocardial infarction and its interactions with other factors.
Background:
Endothelin is an extremely potent vasoconstrictor that may have a role in the pathogenesis of acute myocardial ischaemia. Atrial natriuretic factor is an endogenous antagonist of endothelin. To find the pattern and possible importance of circulating endothelin in ischaemic heart disease, concentrations in normal controls and those in patients with stable and unstable angina, acute myocardial infarction, and chronic cardiac failure were compared. The relation between circulating concentrations of endothelin and atrial natriuretic factor in the aftermath of myocardial infarction was also examined.
Methods:
Eighteen patients with acute myocardial infarction, 10 with unstable angina, 10 with stable angina, 12 with chronic cardiac failure, and 10 normal controls were studied. Endothelin concentration was measured in venous plasma by radioimmunoassay. In patients with acute myocardial infarction simultaneous concentrations of endothelin and atrial natriuretic factor were measured on admission and at one, four, and 24 hours.
Results:
Mean concentrations (SEM) of endothelin were 5.72 (0.19) fmol/ml in controls, 6.56 (0.48) fmol/ml in stable angina, 6.41 (0.48) fmol/ml in unstable angina, and 13.83 (0.95) fmol/ml in chronic cardiac failure. In acute myocardial infarction concentrations were 8.81 (0.69) fmol/ml on admission, 11.85 (1.02) fmol/ml at one hour, 11.88 (1.10) fmol/ml at four hours, and 7.30 (0.49) fmol/ml at 24 hours. Concentrations of atrial natriuretic factor at the same times were 68.1 (13.1) pg/ml, 8.4 (1.5) pg/ml, 24.4 (4.1) pg/ml, and 42.0 (6.9) pg/ml.
Conclusions:
Plasma endothelin is raised in chronic heart failure and in the aftermath of acute myocardial infarction but not in stable or unstable angina. After myocardial infarction endothelin concentrations are raised whereas concentrations of atrial natriuretic factor are relatively low. The role of endothelin in the pathogenesis of acute myocardial infarction and its interactions with other humoral factors require further investigation.