MORPHOLOGY AND FUNCTION OF THE ADRENAL ZONA GLOMERULOSA OF TRANSGENICRATS TGR [MREN2]27 - EFFECTS OF PROLONGED SODIUM RESTRICTION

Heterozygous female transgenic rats for the murine Ren-2 gene (TGR) di splay a high blood pressure, together with a low kidney and high adren al renin content. The effects of prolonged sodium restriction on the m orphology and secretory activity of adrenal zona glomerulosa (ZG) of T GR and their age- and sex-matched Sprague-Dawley control rats (SDR) we re investigated. Under basal conditions, TGR had a moderately hypertro phic ZG, that showed a significantly higher secretion of 18-hydroxylat ed (18OH) steroids: 18-hydroxy-11-deoxycorticosterone (18OH-DOC), 18-h ydroxycorticosterone (18OH-B) and aldosterone (ALDO); ZG cells of TGR showed angiotensin II (AII)-binding site concentrations and ALDO secre tory responses to AII similar to those of SDR ZG cells. Prolonged sodi um restriction increased plasma ALDO level in both SDR and TGR, and si gnificantly raised the volume of ZG. ZG hypertrophy was due to the inc rease in both the number and average volume of its parenchymal cells. The secretion of 18OH-steroids was markedly enhanced in both groups of rats; however, in TGR this rise was exclusively due to increases of 1 8OH-DOC and 18OH-B, while in SDR also ALDO production was enhanced. Th e yield of non-18OH-steroids was not affected. Il-Dehydrocorticosteron e production was not changed in SDR, but doubled in TGR. ZG cells of s odium-restricted SDR and TGR displayed similar increases in their AII- binding site concentration and ALDO secretory response to AII. In conc lusion, our present findings confirm that TGR possess a hypertrophic Z G and an elevated secretory capacity of 18OH-steroids, but show only s light differences in ZG and ZG-cell responses to prolonged sodium depr ivation.