RENAL C-FOS EXPRESSION INDUCED BY ANGIOTENSIN-II IS ENHANCED IN SPONTANEOUSLY HYPERTENSIVE RATS

We compared the effect of a bolus injection of angiotensin II (Ang TT) on the expression of protooncogene c-fos in the renal cortex and medu lla of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) ra ts. Intravenous infusion of 5 ng/kg body weight of Ang II resulted in an immediate rise in systolic blood pressure (SBP) in both SHR and WKY rats. The percent rise in SEP was similar in both strains. Pretreatme nt with Ang II type 1 (AT1)-receptor antagonist, L-158,809 (1 mg/kg) a bolished the presser response in both strains. Competitive reverse tra nscription-polymerase chain reaction (RT-PCR) showed that administrati on of Ang II increased the expression of c-fos mRNA within 10 min in b oth the renal cortex and medulla of SHR significantly higher than WKY rats. Moreover, the enhanced c-fos mRNA expression due to Ang II was s ignificantly suppressed by the pretreatment of L158,809 in both strain s. These findings indicate that c-fos expression in the kidney is medi ated by AT1-receptors and that the renal c-fos response to exogenous A ng II was significantly augmented in SHR compared with WKY rats, sugge sting that this hyperresponsiveness on renal AT1-action may partly con tribute to the progression of renal injury in SHR.