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1 Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3V6; and 2 Institute of Physiology, University of Fribourg, CH-1700 Fribourg, Switzerland
We investigated whether the baroreflex control
of heart rate (HR) stabilizes the product of arterial pressure
(PA) and HR, called the double
product (DP), an indirect indicator of left ventricular oxygen
consumption. During pharmacological increases and decreases of
PA in conscious rabbits, the mean
(±SE) rate of change of the DP with respect to
PA
(dDP/dPA) was
88 ± 36 and
20 ± 36 DP units/mmHg, respectively. Regression analysis of all peak responses obtained in individual rats produced a
dDP/dPA value of 15 ± 16 DP
units/mmHg. These estimates were significantly less than the
dDP/dPA value predicted if HR were
constant (184 ± 7 DP units/mmHg) and were not significantly
different from zero. We also compared values of baroreflex sensitivity
(BRS) from the literature with those calculated to provide ideal
stabilization of the DP. BRS values were significantly correlated with
the calculated ideal values (R = 0.95;
n = 14). BRS averaged 128 ± 24%
of the ideal value in all species and 148 ± 28% in mammals and
birds. Our results suggest that stabilization of the DP is a common
consequence of the baroreflex control of heart rate.
baroreceptors; cardiac metabolism; left ventricular oxygen consumption; heart rate regulation; pressure-rate product
This article has been cited by other articles:
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B. N. Van Vliet, F. Belforti, and J.-P. Montani Baroreflex stabilization of the double (pressure-rate) product at 0.05 Hz in conscious rabbits Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2002; 282(6): R1746 - R1753. [Abstract] [Full Text] [PDF] |
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