Regional vascular responses to prolonged lower body negative pressure in normal subjects.

Published

Journal Article

The purpose of this study was to determine the effects of sustained unloading of baroreceptors in humans. The regional hemodynamic responses to lower body negative pressure (LBNP) were determined in 20 normal subjects. LBNP at -10 mmHg for 1 h decreased central venous pressure (CVP) without affecting blood pressure or heart rate, suggesting that only cardiopulmonary baroreceptors were unloaded. Forearm blood flow (FBF) and splanchnic blood flow (SBF) both decreased. Renal blood flow (RBF) did not change, but glomerular filtration rate (GFR) increased. Plasma renin activity rose slightly, whereas plasma norepinephrine levels did not change. Peak LBNP (either -20 or -40 mmHg for 1 h) caused a further decline in CVP and narrowed pulse pressure, thus unloading both arterial and cardiopulmonary baroreceptors. FBF returned to base-line values and SBF decreased further. RBF fell and the GFR remained increased. Plasma renin activity increased further, and plasma norepinephrine level rose. Thus the forearm and splanchnic circulations are sensitive to sustained unloading of cardiopulmonary baroreceptors; renal vasoconstriction occurs with additional unloading of arterial baroreceptors. Renin-angiotensin system activation during LBNP may be pertinent to the preservation of glomerular filtration.

Full Text

Duke Authors

Cited Authors

  • Hirsch, AT; Levenson, DJ; Cutler, SS; Dzau, VJ; Creager, MA

Published Date

  • July 1, 1989

Published In

Volume / Issue

  • 257 / 1 Pt 2

Start / End Page

  • H219 - H225

PubMed ID

  • 2750938

Pubmed Central ID

  • 2750938

Electronic International Standard Serial Number (EISSN)

  • 2163-5773

International Standard Serial Number (ISSN)

  • 0002-9513

Digital Object Identifier (DOI)

  • 10.1152/ajpheart.1989.257.1.h219

Language

  • eng