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Baroreflex stabilization of the double product
1Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3V6. vanvliet@morgan.ucs.mun.ca
The American Journal of Physiology
|November 24, 1999
Summary
The baroreflex control of heart rate helps stabilize the double product (DP), an indicator of heart oxygen use. This stabilization is a common outcome of the baroreflex mechanism across species.
Area of Science:
- Physiology
- Cardiovascular Regulation
Background:
- The double product (DP), calculated as the product of arterial pressure and heart rate, is an indirect measure of myocardial oxygen consumption.
- The baroreflex is a critical physiological mechanism for regulating arterial pressure and heart rate.
Purpose of the Study:
- To investigate whether the baroreflex control of heart rate (HR) contributes to the stabilization of the arterial pressure (P(A)) and HR product (DP).
- To assess the role of baroreflex sensitivity (BRS) in maintaining stable DP levels.
Main Methods:
- Pharmacological manipulation of arterial pressure in conscious rabbits to measure changes in DP.
- Analysis of the rate of change of DP with respect to P(A) (dDP/dP(A)).
- Comparison of experimentally derived dDP/dP(A) values with theoretical predictions and literature values for BRS.
Main Results:
- The rate of change of DP with respect to P(A) was significantly lower than predicted for a constant HR, indicating stabilization.
- Experimental estimates of dDP/dP(A) were not significantly different from zero.
- Baroreflex sensitivity values from the literature were significantly correlated with calculated ideal values for DP stabilization.
Conclusions:
- The baroreflex control of heart rate plays a significant role in stabilizing the double product.
- DP stabilization appears to be a common consequence of baroreflex function across different species.