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- Title
Ionic effects of angiotensin II and their role in the activation of the Na<sup>+</sup>/H<sub>+</sub> antiporter.
- Authors
Flores, Guillermo; Minghao Ye; Lapointe, Michael; Batlle, Daniel
- Abstract
The possible interdependence of the effects of angiotensin II (Ang II) on intracellular pH (pHi), free cytosolic calcium (Cai2+) and free cytosolic sodium (Nai+) was studied in cultured vascular smooth muscle cells (VSMC) from rat aorta. Cells were loaded with either BCECF/AM, SBFI/AM or Fura-2 for measurement of pHi, Nai+ or Cai2+, respectively. Superfusing with a HEPES solution containing Ang II(1 µM) caused a progressive increase in Nat Concurrent pHi changes measured in parallel experiments showed that Ang II caused a brief cell acidification followed by a delayed alkalinization, which is due to activation of the Na+/H+ antiporter. Concurrent Cai2+ changes measured in parallel experiments showed that Ang II caused a prompt rise in Cai2+ with a peak response at ~30 seconds followed by a rapid recovery. Obliteration of the Ang II-induced rise in Cai2+ using a Ca2+ chelator (BAPTA), prevented the initial cell acidification but did not prevent the delayed rise in pHi, which reflects stimulation of the Na+/H+ antiporter. Our data thus show that in cultured VSMC neither the rise in Cai2+ nor the fall in pHi caused by Ang II is a total prerequisite for activation of the Na+/H+ antiporter by this agonist.
- Subjects
ANGIOTENSIN II; HYDROGEN ions; IONIC structure; SODIUM; ACIDIFICATION
- Publication
Kidney International, 1996, Vol 49, pS122
- ISSN
0085-2538
- Publication type
Article