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Biphasic changes in heart performance with food restriction in rats
K A McKnight1, H Rupp, K S Dhalla
1Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 24, 1999
Summary
Very-low-calorie dieting initially enhances heart performance through increased catecholamines, but prolonged restriction leads to depressed cardiac function in rats. This study investigates the impact of severe food restriction on cardiovascular health.
Area of Science:
- Cardiovascular Physiology
- Metabolic Research
- Animal Models in Cardiology
Background:
- Very-low-calorie diets (VLCDs) can induce significant physiological changes.
- Understanding the cardiac effects of severe caloric restriction is crucial for metabolic and cardiovascular health.
- Previous research indicates potential impacts of dietary interventions on heart function.
Purpose of the Study:
- To investigate the acute and chronic effects of food restriction, mimicking VLCDs, on cardiac performance in rats.
- To explore the relationship between food restriction, catecholamine levels, and cardiac function.
- To determine the temporal changes in hemodynamic parameters and myocardial catecholamine concentrations during restricted feeding.
Main Methods:
- Rats were subjected to 25% of ad libitum food intake for 14 days.
- Cardiac function was assessed by measuring left ventricular systolic pressure and rates of pressure development/fall.
- Plasma and cardiac tissue concentrations of catecholamines (norepinephrine, epinephrine, dopamine) and dopamine beta-hydroxylase activity were analyzed at various time points.
Main Results:
- Food restriction initially increased heart weight, left ventricular systolic pressure, and blood pressure, peaking around day 7.
- Plasma norepinephrine and epinephrine concentrations rose significantly, coinciding with increased cardiac workload.
- Cardiac catecholamine levels (dopamine, norepinephrine, epinephrine) were elevated during the restriction period, while dopamine beta-hydroxylase activity showed an initial rise followed by a decrease.
- After 14 days, cardiac performance parameters and blood pressure decreased, indicating cardiac depression.
Conclusions:
- Short-term severe food restriction initially enhances cardiac performance, likely mediated by increased catecholamine activity.
- Prolonged food restriction leads to a decline in cardiac function and hemodynamic parameters.
- These findings suggest a biphasic response of the heart to severe caloric restriction, with potential implications for understanding the cardiovascular risks associated with VLCDs.
