Endogenous inhibitor of the na-k-cl cotransport system in inbred
dahl rats.
Alvarez-Guerra, M., F. Vargas, J. O. Alda, and R. P. Garay.
Inserm U400, Facult[acute]e de M[acute]edecine, 94010
Cr[acute]eteil, France, Fisiologia, Facultad de Medicina, Zaragoza
and Fisiologia, Facultad de Medicina, Granada, Spain
APStracts 3:0223F, 1996.
Dahl salt-sensitive rats seem characterized by an ubiquitary increase
in Na-K-Cl cotransport activity. Here, an endogenous inhibitor of the
Na-K-Cl cotransport system (CIF), was investigated in inbred Dahl
salt-sensitive (DS) and salt-resistant (DR) rats. The animals were
orally loaded for 10 days with 2% NaCl. Plasma from salt-loaded DS
rats inhibited cotransport with IC50 = 6.4 +/- 0.6 % (% plasma
concentration, v/v) vs. 24.2 +/- 2.2 % in DR rats (p <
0.0001). In urines, IC50 for cotransport inhibition was constantly
lower in DS before and all during the whole salt-loading period
(after 10 days of salt-loading IC50 was 2.59 +/- 0.11 % and 6.00 +/-
0.24 % in DS and DR rats respectively, p < 0.0001). After 3
days of salt-loading, higher salt-appetite in DS rats magnified the
differences in urinary CIF excretion. In erythrocytes from DS rats,
increased cotransport activity was strongly correlated with urinary
CIF excretion (r = 0.967). In conclusion, Dahl salt-sensitive rats
present increased plasmatic and urinary CIF levels. This can be a
compensatory phenomenon to reduce cotransport hyperactivity and
increased NaCl reabsorption at the thick ascending limb of Henle's
loop.
Received 22 April 1996; accepted in final form 14 November 1996.
APS Manuscript Number F122-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996