Sodium increases angiotensin II receptors in neuronal cultures from brains of normotensive and hypertensive rats.

Neuronal cultures from one-day-old brains of Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats were used to determine the effect of sodium ions on angiotensin II (Ang II) receptors in order to understand the mechanism of action of sodium at the cellular level. Incubation with sodium chloride of neuronal cultures from WKY rats caused a rapid and dose-dependent increase in the specific binding of 125I-Ang II to its receptors. A 260% increase in the binding was observed with 150 mM NaCl. Neuronal cultures from SH rat brains showed a similar sodium-stimulated increase in Ang II binding; however this increase was 150% greater than that observed in neuronal cultures from WKY rat brain. Kinetic studies of the effects of sodium ions on both WKY and SH neuronal cultures showed an increase in the dissociation of 125I-Ang II from its receptors in the presence of sodium ions. In addition, Scatchard analysis revealed that the increase in binding caused by sodium was due to an increase in the number of Ang II receptors. These observations indicate that sodium ions increase the number of Ang II specific receptors in intact neuronal cells and that this stimulation was more pronounced in neuronal cells from SH rat brains compared with WKY controls.