We examined the effect of intravascular volume expansion (VE) on the arterial baroreflex control of pulse rate (PR) in conscious, chronically instrumented monkeys tethered in their cages. A total of five monkeys was studied after surgical implantation of catheters in the descending aorta, the left atrium, and the internal jugular vein. Mean arterial blood pressure (MABP)-PR stimulus response curves were constructed by decreasing and increasing blood pressure with nitroprusside and phenylephrine, respectively. The data were analyzed with a regression analysis that generated a sigmoid curve and the maximum sensitivity (slope) of the curve. The data were obtained before and after VE with an isotonic isoncotic dextran solution equal to 20% of the estimated blood volume. After VE, the MABP-PR curve shifted to the right at the high blood pressures, and there was a significant decrease in the maximum sensitivity from 5.65 ± 1.44 for control to 2.14 ± 0.63 after VE (P < 0.05). We concluded that VE attenuates the baroreflex control of heart rate in the conscious nonhuman primate.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - 1989|
ASJC Scopus subject areas
- Physiology (medical)