Central blood volume and blood pressure in conscious primates.
Conscious intact (I) and sinoaortic-denervated monkeys (SAD) were studied to determine the extent to which high-pressure receptors contribute to the maintenance of arterial blood pressure (BP) when venous return is decreased by hemorrhage (H) or lower body negative pressure (LBNP). In the I animals, mean BP did not decrease significantly until 5% of the estimated blood volume (EBV) was removed, whereas, with sinoaortic denervation, mean BP decreased significantly when less than 2% of EBV was removed. Left atrial pressure (LAP) decreased similarly in both groups of animals. In the I group during LBNP, mean BP did not change significantly, whereas pulse pressure decreased significantly when LBNP was decreased to -5 cmH2O. In the SAD animals, mean BP decreased significantly at an LBNP of -2 cmH2O, and at -5 cmH2O mean BP declined from 134.1 +/- 4 to 102.7 +/- 7 mmHg. LAP decreased similarly in both groups of animals. The data support the view that a nonhypotensive reduction in venous return unloads arterial baroreceptors sufficiently to activate the arterial baroreflex, probably through reductions in pulse pressure. In addition, low-pressure receptors by themselves do not appear to contribute importantly to blood pressure maintenance when venous return is decreased by either LBNP or a nonhypotensive hemorrhage.
Cornish
K G
KG
Department of Physiology and Biophysics, University of Nebraska College of Medicine, Omaha 68105-1065.
Gilmore
J P
JP
McCulloch
T
T
D000818:Animals; D001794:Blood Pressure; D001810:Blood Volume; D003243:Consciousness; D006339:Heart Rate; D006470:Hemorrhage / Q000503:physiopathology; D008251:Macaca / Q000502:physiology*; D008253:Macaca mulatta / Q000502:physiology*; D008255:Macaca radiata / Q000502:physiology*; D010215:Papio / Q000502:physiology*; D012016:Reference Values; D013045:Species Specificity