Effects of posture and positive airway pressure on plasma atrial natriuretic peptide and renal urodilatin excretion.
OBJECTIVE
To determine whether a coupling of plasma atrial natriuretic peptide (ANP) and renal excretion of urodilatin (U(URO)V)--recently observed during supraphysiological concentrations of ANP--may also be detected during moderate changes in ANP levels, i.e. if ANP is increased by supine positioning and decreased by applying continuous positive airway pressure (CPAP).


METHODS
We investigated 10 healthy male volunteers, orally hydrated with 200 ml water/h, in a randomized crossover study for periods of 1 hour following 2 protocols. Protocol 1: sitting and supine position. Protocol 2: sitting with and without a CPAP of 8 cm H2O.


RESULTS
ANP increased ongoing from the sitting to the supine position (SIT-1: 13.2 +/- 4.7; SUP: 27.9 +/- 21.9 pg x ml(-1); p < 0.01) during protocol 1 and decreased after the onset of CPAP in seated subjects (SIT-2: 16.9 +/- 7.9; SIT-CPAP: 13.9 +/- 6.5 pg x ml(-1); p < 0.05) during protocol 2. U(URO)V decreased slightly, but not significantly, during protocol I (SIT-1: 63.9 +/- 21.7; SUP: 49.9 +/- 13.2 fmol x min(-1)) and remained unchanged after institution of CPAP in the sitting position (SIT-2: 68.5 +/- 25.2; SIT-CPAP: 68.5 +/- 50.2 fmol x min(-1)). Correlation analysis revealed no relationship between plasma ANP and U(URO)V.


CONCLUSIONS
Moderate variations in the levels of ANP in water-loaded volunteers do not induce parallel changes in the urinary excretion of urodilatin.
Heringlake
M
M
Clinic for Anesthesiology, Medical University of Lübeck. Heringlake@t-online.de
Klaus
S
S
Bahlmann
L
L
Sehested
J
J
Pagel
H
H
Schmucker
P
P
D000328:Adult; D009320:Atrial Natriuretic Factor / Q000097:blood* / Q000378:metabolism*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000098:blood supply* / Q000502:physiology*; D008297:Male; D009318:Natriuresis / Q000502:physiology; D010446:Peptide Fragments / Q000378:metabolism*; D011175:Positive-Pressure Respiration; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D013223:Statistics as Topic
D010446:Peptide Fragments; C056452:Ularitide; D009320:Atrial Natriuretic Factor