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Biomedical subjects

E Sperling

Publications and source records attributed to E Sperling.

At least 19 recordsLinked to original sources
PubMed1991

The effect of sodium intake on angiotensin content of the rat adrenal gland.

To determine whether dietary sodium intake modifies the generation of adrenal-produced angiotensins and/or their relative proportions, Sprague-Dawley rats were maintained on a low (0.02%), normal (0.4%), or high (1.5%) sodium intake for 5 days. The animals were then killed by decapitation at 0900 h, and their adrenal glands were removed and dissected into two parts: capsular tissue, containing the zona glomerulosa (ZG), and the decapsulated adrenal gland. The tissue was frozen in liquid nitrogen and extracted, and the individual angiotensins [angiotensin-II (AII), angiotensin-III (AIII), angiotensin-I (AI), and Des-Asp-angiotensin-I (Des-Asp-AI)] were separated by HPLC and quantitated by RIA. On a normal sodium intake, the molar contents of the four angiotensins were similar in ZG, ranging from 3.1-6.6 pmol/g, although AII was present in a 60-70% higher concentration than AIII. In the decapsulated adrenal, the concentrations of the various angiotensins were again similar, but the absolute levels (per g tissue) were significantly (P less than 0.02) less than those in the ZG layer. With sodium restriction, the AII content increased more than 2-fold in the ZG, but not in the decapsulated adrenal tissue. In contrast, both AI and Des-Asp-AI significantly (P less than 0.01) decreased with sodium restriction, so that their contents on the low salt diet were only 15-20% of those observed on the high sodium diet. Thus, there was an inverse correlation (P less than 0.001) between the salt content of rat chow and the AII content of the ZG. The correlation between salt intake and AI as well as Des-Asp-AI levels was direct and significant (P less than 0.02). The AIII level in the ZG was similar on all diets. After a lag period, ZG AII increased sharply between 16-48 h of sodium restriction. These data document that sodium intake has a profound effect on the angiotensin content of the ZG, with sodium restriction substantially increasing the levels of AII while reducing the level of its substrate, AI. This also appears to be unique for glomerulosa cells, as in the decapsulated adrenal gland there is little if any change with sodium restriction. We conclude that these sodium-mediated changes in tissue AII production may be involved in the increased responsiveness of glomerulosa cells to aldosterone secretagogues during sodium restriction.

Adrenal Glands↗
PubMed1991

Potassium-stimulated angiotensin release from superfused adrenal capsules and enzymatically dispersed cells of the zona glomerulosa.

The cells of the adrenal cortex contain angiotensin-II (AII), but whether this peptide is synthesized there (vs. internalized from the systemic circulation), whether it is secreted, and whether it is important in aldosterone production remain uncertain. To address these issues, we studied AI and AII release from superfused rat adrenal capsules and dispersed glomerulosa cells. Superfused adrenal capsules released 7-fold more AII in 270 min than the capsules originally contained (495 +/- 101 fmol AII/rat released vs. 66 +/- 8 fmol AII/rat tissue content). The amount of AI released in the same period only slightly exceeded the tissue content. In response to higher potassium concentrations in the medium (9 vs. 3.6 mM K+), adrenal capsules and dispersed glomerulosa cells both released significantly more AI and AII into the superfusate. This release of AI and AII was oscillatory. The oscillations occurred in each of 15 experiments, with a period of 45-90 min. Decapsulated adrenal glands (the zona faciculata/reticularis plus medulla) also contained and released AII, but did not respond to potassium stimulation. There was a highly significant correlation between AII and aldosterone release. This was especially apparent if aldosterone secretion was examined during oscillations of AII release (r = 0.97; P less than 0.0001). We conclude that AII is synthesized in the zona glomerulosa and can be released in response to stimuli. The close correlation between AII and aldosterone secretion suggests that locally produced AII may play an important role in aldosterone biosynthesis.

Adrenal Glands↗