A. Muscella et al., Angiotensin II stimulates the Na+/H+ exchanger in human umbilical vein endothelial cells via AT1 receptor, LIFE SCI, 65(22), 1999, pp. 2385-2394
Angiotensin II (Ang II) has an important role in cardiovascular regulation
and in the control of electrolyte balance, and its role in the regulation o
f Na+ transcellular movements through its actions on the activity of Na+/K ATPase is well documented. We showed previously that human umbilical vein
endothelial cells (HUVEC) express the Ang II type 1 (AT1) receptor, which m
ediates Ang II modulation of Na+/K(+)ATPase activity (1). We here investiga
te the effects of Ang II on the activity of the Na+/H+ exchanger in HUVEC.
When compared with controls, incubation of HUVEC for 20 min with different
concentrations of Ang II provoked significant increases in Na+/H+ activity.
The stimulation was dose dependent between 1 and 10 nM Ang II and varied w
ith time of incubation up to 20 min. The maximal response, obtained with 10
nM Ang II after 20 min treatment, resulted in a 65% increment in Na+/H+ ac
tivity. Preincubation of HUVEC with 10 mu M DuP753 blocked Na+/H+ activatio
n by Ang II. These results suggest that the effects of Ang II on both the N
a+/K(+)ATPase and the Na+/H+ exchanger may increase the transendothelial fl
ux of Na+ and are mediated by the AT1 receptor.