Activation of the renal endothelin-1 system in the long-lasting
response to postural changes. relationship with renin-angiotensin
system.
Modesti, Pietro Amedeo, Ilaria Cecioni, Alessandra Naldoni, Angela
Migliorini, and Gian Gastone Neri Serneri.
Clinica Medica I, University of Florence, V.le Morgagni 85, 50134
Florence, ITALY
APStracts 2:0403H, 1995.
The present study was performed in 7 healthy subjects (aged 22-35
years) to investigate 1) whether plasma and urinary endothelin-1 (ET
-1) are involved in the response to postural changes, and 2) the
relationship between ET-1 formation and the renin- angiotensin system
(RAS). Six hour of standing caused a prompt but very short-lasting
increase in plasma ET-1 concentration (59 % after 5 minutes, 12 %
after 1 hour) and a notable and sustained enhancement of urinary ET-1
excretion (from 0.59 +/- 0.10 pg/min to 1.43 +/- 0.28 pg/min, 142 %,
p < 0.001). Plasma renin activity increased by 169 % after 1
hour of standing. A parallel contraction of urinary volume (- 36 %),
sodium excretion (- 55 %) and free water reabsorption (- 24 %)
occurred. The return to the supine position after 6 hours of
orthostasis caused a reduction to baseline values of the ET-1 urinary
excretion and urinary volume within 2 hours. Inhibition of
angiotensin converting enzyme blunted, but did not eliminate, the
orthostasis-induced increase in ET-1 urinary excretion (100 %, p
< 0.002) and changes in the renal functions. The present results
indicate that renal ET-1 is involved in the hemodynamic long-lasting
responses to postural changes, that its increase is partially
controlled by RAS and suggest that ET-1 might play a role in the
regulation of renal function in humans.
Received 27 February 1995; accepted in final form 6 September
1995.
APS Manuscript Number H182-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.