Quantitative analysis of renin gene expression in extrarenal tissues by polymerase chain reaction method.

OBJECTIVE: To evaluate the significance of locally synthesized renin in the pathogenesis of hypertension, we investigated modulation of the renin gene expression in extrarenal tissues.
DESIGN: Expression levels of renin messenger (m)RNA in various tissues were determined in the genetically hypertensive rats and their control strains. Effects of salt, captopril and clonidine upon renin gene expression were also investigated.
METHODS: Due to the very low expression level of renin mRNA in extrarenal tissues, a competitive polymerase chain reaction method of assessment was applied. Total RNA from various tissues combined with a synthetic deletion-mutated renin RNA were reverse-transcribed and the resultant complementary DNA mixtures were amplified in one reaction in which the same primers were used.
RESULTS: Expression levels of the renin mRNA in various parts of the central nervous system of 4-week-old spontaneously hypertensive rats were approximately twofold higher than those of age-matched Wistar-Kyoto rats and expression levels in the brain were positively modulated by the administration of either captopril or clonidine.
CONCLUSIONS: The importance of the brain renin angiotensin system in the pathogenesis of hypertension in spontaneously hypertensive rats was strongly suggested.