What is the clinical evidence from this study?

Study design: Other. Population: Baroreceptor denervation. Intervention: Sinoaortic baroreceptor denervation vs. Normal dogs. Primary outcome: Average 24-hour mean arterial blood pressure.

May 1, 1973Open Access

Role of the Baroreceptor Reflex in Daily Control of Arterial Blood Pressure and Other Variables in Dogs

Key Result

Sinoaortic baroreceptor denervation in dogs yielded an average 24-hour mean arterial blood pressure of 112.7 mm Hg versus 101.6 mm Hg in normal dogs, primarily increasing blood pressure variability.

PICO

Population

Normal and sinoaortic baroreceptor-denervated dogs monitored continuously for 24 hours to assess hemodynamic variability.

Exposure / Comparator

Sinoaortic baroreceptor denervation vs Normal dogs

Primary Outcome

Average 24-hour mean arterial blood pressure

Main Result

Absolute Event Rate: 112.7% vs 101.6%

Abstract

Normal and sinoaortic baroreceptor-denervated dogs were monitored continuously (24 hours a day) to quantify the role of the baroreceptors in determining the average level and the variability of arterial blood pressure, heart rate, cardiac output, and total peripheral resistance. The frequency of occurrence over 24-hour periods was obtained for each variable using a fiber optic curve-scanning system to read the variables from continuously recorded charts and a digital computer system to plot curves. The results indicate that the degree of hypertension previously reported for this preparation has been highly exaggerated, presumably due to the methods of study. The average 24-hour mean arterial blood pressure was 101.6 mm Hg in normal dogs and only 112.7 mm Hg in baroreceptor-denervated dogs. The normal dogs exhibited narrowly distributed 24-hour frequency distribution curves for blood pressure; in contrast the denervated dogs exhibited curves with twice the 24-hour standard deviation. Similar analysis indicated that the baroreceptors exerted less influence on the daily stabilization of heart rate than they did on arterial blood pressure and that they had very little if any influence on the daily stabilization of cardiac output and total peripheral resistance. Hemodynamic variables during postural changes were studied along with diurnal rhythms. We concluded that the primary function of the baroreceptor reflex is not to set the chronic level of arterial blood pressure but, instead, to minimize variations in systemic arterial blood pressure, whether these variations are caused by postural changes of the animal, excitement, diurnal rhythm, or even spontaneous fluctuations of unknown origin.