Effect of micro-injection angiotensin II into subfornical organ in rats on Na+, K(+)-ATPase activity in proximal tubules / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To investigate the effect of micro-injection Ang II into the subfornical organ (SFO) on the proximal tubules (PT) Na+, K(+)-ATPase activity in rats and its mechanism.</p><p><b>METHODS</b>SFO in SD rats was administrated respectively with Ang II (20 ng), or losartan (5 microg) and AngII (20 ng) successively. The levels of serum EDLS and plasm AngII were assessed with radioimmunoassay (RIA). The PT segments were microdissected freehand and their Na+, K(+)-ATPase activities were assessed by liquid scintillation counter (LSC).</p><p><b>RESULTS</b>The serum EDLS levels increased significantly compared with a CSF group after SFO administration with Ang II; The Na+, K(+)-ATPase activities in PT segments decreased significantly at 30 min and 60 min after SFO administration with Ang II. There was a negative linear correlation between serum EDLS level and the Na+, K(+)-ATPase activity of PT segments in rats administrated with Ang II (r = -0.938).</p><p><b>CONCLUSION</b>Inhibition of the Na+, K(+)-ATPase activity in PT as a result of administration of Ang II in SFO is mediated by AT1 receptors. The increase in EDLS release may play an important role in this inhibition.</p>