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Platelet alpha-adrenoceptor density in patients with left ventricular volume overload
1Biological and Medical Research Department (MBC-03), King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
Journal of Medicine
|January 1, 1997
Summary
Aortic regurgitation significantly increases platelet alpha 2-adrenoceptors in heart disease, while mitral regurgitation shows a smaller effect. Severity of volume overload influences these changes.
Area of Science:
- Cardiology
- Pharmacology
- Molecular Biology
Background:
- Left ventricular heart disease can cause aortic and mitral regurgitation.
- These conditions may affect platelet alpha 2-adrenoceptors.
- The influence of overload origin and severity on these receptors is not fully understood.
Purpose of the Study:
- To evaluate if aortic and mitral regurgitation affect platelet alpha 2-adrenoceptor density differently.
- To determine the impact of overload origin and severity on these receptors.
Main Methods:
- Measured platelet alpha 2-adrenoceptor density and binding affinities using [3H]-yohimbine.
- Compared receptor density in healthy controls, patients with aortic regurgitation, mitral regurgitation, and mixed valve regurgitation.
- Assessed plasma epinephrine levels and ejection fractions.
Main Results:
- Patients with left heart valvular disease showed a 57% increase in receptor density.
- Aortic regurgitation (AVR) led to a 91% increase, mitral regurgitation (MVR) a 43% increase, and mixed (MOL) a 23% increase.
- The increase in AVR was significantly greater than in MOL, correlating weakly with ejection fraction.
Conclusions:
- Aortic regurgitation significantly elevates platelet alpha 2-adrenoceptor density in left heart valvular disease.
- Mitral valve disease has a less significant effect on these receptors.
- Findings suggest differences in hemodynamic influence and overload severity contribute to receptor changes.