Hemodynamic, renal, and hormonal responses to lower body positive pressure in human subjects. 1996

E T Mannix, and M O Farber, and G R Aronoff, and M E Brier, and M H Weinberger, and P Palange, and F Manfredi
Indiana University Department of Medicine, Veterans Affairs Medical Center, Indianapolis 46202, USA.

Studies in healthy human subjects subjected to lower body positive pressure (LBPP) have failed to elucidate many of the physiologic effects of this maneuver. In 7 healthy, well-hydrated men we studied the following responses to LBPP (35 mm Hg, 1 hour, supine position): systemic and renal hemodynamics; urine volume (UV), urine osmolality (Uosm), and urine sodium level (UNaV); free water (CH20) and osmolar (Cosm) clearances; plasma renin activity (PRA); levels of aldosterone (PA), cortisol (CORT), norepinephrine (NE), atrial natriuretic peptide (ANP), and vasopressin (AVP); osmolality (Posm); and serum sodium level. Subjects were restudied on a control day with zero trouser pressure. The recorded changes (p < 0.05) when comparing the LBPP day with the control day were as follows: fractional Na+ reabsorption increased (98.7% +/- 0.2% to 99.3% +/- 0.1%) and UNaV decreased (0.19 +/- 0.03 mEq/min to 0.10 +/- 0.01 mEq/min), with concomitant increases in PRA (1.7 +/- 0.2 ng/ml/90 min to 4.5 +/- 1.8 ng/ml/90 min), PA (7.7 +/- 0.7 ng/dl to 9.3 +/- 1.5 ng/dl), and CORT (13.0 +/- 2.6 mg/dl to 19.2 +/- 3 mg/dl); the increase in blood pressure with LBPP (96 +/- 3 mm Hg to 112 +/- 4 mm Hg) was greater than that during control conditions. Renal plasma flow tended to display an interactive pattern across days, with a slight decline during LBPP (5%) and a slight elevation under control conditions (9%). On the LBPP day only, filtered Na+ declined (15 +/- I mEq/min to 12 +/- 1 mEq/min) as a function of reduced glomerular filtration rate (112 +/- 5 ml/min to 91 +/- 7 ml/min), blood volume decreased (by 2.7% +/- 0.7%), CO decreased (5.5 +/- 0.3 L/min to 4.7 +/- 0.3 L/min), and stroke volume declined (101 +/- 6 ml to 84 +/- 3 ml). On both days, NE increased (control, 221 +/- 23 pg/ml to 340 +/- 33 pg/ml; LBPP, 236 +/- 17 pg/ml to 369 +/- 31 pg/ml) and ANP increased (control, 47 +/- 7 pg/ml to 97 +/- 21 pg/ml; LBPP, 49 +/- 10 pg/ml to 104 +/- 30 pg/ml). We concluded that LBPP reduces renal sodium excretion. The mechanism for this reduction is not known, although it did occur in association with an increase in plasma renin activity, which in turn results from mechanical reduction of renal perfusion, stress-related CORT stimulation, a reflex-based elevation in peripheral vascular resistance leading to a reflex increase in plasma renin activity, or a combination of these.

UI MeSH Term Description Entries
D007668 Kidney Body organ that filters blood for the secretion of URINE and that regulates ion concentrations. Kidneys
D008297 Male Males
D009320 Atrial Natriuretic Factor A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight PEPTIDES derived from a common precursor and secreted mainly by the HEART ATRIUM. All these peptides share a sequence of about 20 AMINO ACIDS. ANF,ANP,Atrial Natriuretic Peptide,Atrial Natriuretic Peptides,Atriopeptins,Auriculin,Natriuretic Peptides, Atrial,ANF (1-126),ANF (1-28),ANF (99-126),ANF Precursors,ANP (1-126),ANP (1-28),ANP Prohormone (99-126),ANP-(99-126),Atrial Natriuretic Factor (1-126),Atrial Natriuretic Factor (1-28),Atrial Natriuretic Factor (99-126),Atrial Natriuretic Factor Precursors,Atrial Natriuretic Factor Prohormone,Atrial Natriuretic Peptide (1-126),Atrial Pronatriodilatin,Atriopeptigen,Atriopeptin (1-28),Atriopeptin (99-126),Atriopeptin 126,Atriopeptin Prohormone (1-126),Cardiodilatin (99-126),Cardiodilatin Precursor,Cardionatrin I,Cardionatrin IV,Prepro-ANP,Prepro-CDD-ANF,Prepro-Cardiodilatin-Atrial Natriuretic Factor,Pro-ANF,ProANF,Proatrial Natriuretic Factor,Pronatriodilatin,alpha ANP,alpha-ANP Dimer,alpha-Atrial Natriuretic Peptide,beta-ANP,beta-Atrial Natriuretic Peptide,gamma ANP (99-126),gamma-Atrial Natriuretic Peptide,Natriuretic Peptide, Atrial,Peptide, Atrial Natriuretic,Peptides, Atrial Natriuretic,Prepro ANP,Prepro CDD ANF,Prepro Cardiodilatin Atrial Natriuretic Factor,Pro ANF,alpha ANP Dimer,alpha Atrial Natriuretic Peptide,beta ANP,beta Atrial Natriuretic Peptide,gamma Atrial Natriuretic Peptide
D009638 Norepinephrine Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic. Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D011312 Pressure A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Pressures
D012039 Regional Blood Flow The flow of BLOOD through or around an organ or region of the body. Blood Flow, Regional,Blood Flows, Regional,Flow, Regional Blood,Flows, Regional Blood,Regional Blood Flows
D012083 Renin A highly specific (Leu-Leu) endopeptidase that generates ANGIOTENSIN I from its precursor ANGIOTENSINOGEN, leading to a cascade of reactions which elevate BLOOD PRESSURE and increase sodium retention by the kidney in the RENIN-ANGIOTENSIN SYSTEM. The enzyme was formerly listed as EC 3.4.99.19. Angiotensin-Forming Enzyme,Angiotensinogenase,Big Renin,Cryorenin,Inactive Renin,Pre-Prorenin,Preprorenin,Prorenin,Angiotensin Forming Enzyme,Pre Prorenin,Renin, Big,Renin, Inactive
D004326 Drinking The consumption of liquids. Water Consumption,Water Intake,Drinkings
D006439 Hemodynamics The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM. Hemodynamic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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