Angiotensin II Induces in vivo c-fos Expression from Rat Renal Cortex and Medulla

In order to verify whether angiotensin II (Ang II) induced in vivo protooncogene, c-fos, expression in the rat renal cortex and medulla, we administered various concentrations of Ang II to Wistar rats and measured the c-fos expression from the renal cortex and medulla using the method of Northern hybridization. c-fos expression induced by 1 microgram (1.6 x 10(-6) M) of atrial natriuretic peptide (ANP) was also examined. The result was that the peak expression of c-fos mRNA was observed at approximately 10 min after Ang II administration in both rat renal cortex and medulla. This expression was reduced to the control level at 30 min. The measurement of the concentration of injected-Ang II and c-fos mRNA expression revealed that the peak expression of c-fos mRNA in the renal cortex and medulla was detected at the concentration of 1.0 x 10(-8) M and 1.0 x 10(-9) M Ang II, respectively. Nevertheless, ANP had no significant effect on the increase in c-fos mRNA expression. These data revealed that Ang II transiently increases the in vivo c-fos expression in both rat renal cortex and medulla but ANP does not. This protooncogene expression may induce vascular and mesangial proliferation in the kidney.