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Modification of catecholamine-induced changes in heart function by food restriction in rats
K A McKnight1, H Rupp, R E Beamish
1Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Cardiovascular Drugs and Therapy
|June 1, 1996
Summary
Severe food restriction impacts adrenergic mechanisms and heart function. Dieting may lead to bradycardia and altered cardiac responses, suggesting caution during weight reduction.
Area of Science:
- Cardiology
- Endocrinology
- Physiology
Background:
- Dieting for weight reduction is common.
- Severe food restriction can significantly alter physiological processes.
- Adrenergic mechanisms play a crucial role in cardiovascular regulation.
Purpose of the Study:
- To investigate the effects of severe food restriction on adrenergic mechanisms and heart function in rats.
- To determine how a 25% reduction in caloric intake influences cardiac and plasma catecholamine levels.
- To assess the impact of diet restriction on cardiac electrophysiology and contractility.
Main Methods:
- Rats were subjected to severe food restriction (25% of ad libitum intake) for 14 days.
- Cardiac and plasma norepinephrine and epinephrine levels were measured.
- Electrocardiograms (ECG) and cardiac contractility (dP/dt) were assessed.
- Beta-adrenergic receptor density and binding affinity were analyzed.
Main Results:
- Food-restricted rats showed increased cardiac and plasma norepinephrine and epinephrine.
- Bradycardia and ECG abnormalities (prolonged QRS and QT intervals) were observed.
- Cardiac contractility and inotropic responses to epinephrine were reduced.
- A significant decrease in beta-adrenergic receptor density was found in the heart.
Conclusions:
- Severe food restriction markedly affects adrenergic mechanisms and heart function.
- Downregulation of cardiac beta-adrenergic receptors may explain reduced contractile force and arrhythmias.
- Caution is advised during the early stages of severe dieting for weight reduction due to potential cardiovascular effects.
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