title: StAR expression and the long-term aldosterone response to high-potassium diet in Wistar-Kyoto and spontaneously hypertensive rats.
abstract: ANG II and potassium are known to increase steroidogenic acute regulatory protein (StAR) levels. However, a corresponding increase in StAR mRNA levels has so far been observed only in response to ANG II. We therefore studied the regulation of adrenal StAR mRNA expression in the context of dietary potassium-stimulated aldosterone production. Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were fed a diet containing either 1 or 4% KCl for 5 days. The high-potassium diet increased StAR mRNA levels within the zona glomerulosa in both strains, as demonstrated by in situ hybridization. However, aldosterone production increased in WKY but not in SHR (WKY: from 22.8 +/- 4.8 to 137 +/- 25 ng/100 ml, P < 0.001, vs. SHR: from 29 +/- 3.8 to 51 +/- 10.2 ng/100 ml, not significant). This increase was associated with an increase in Cyp11b2 mRNA levels in WKY (3-fold; P < 0.001) but not in SHR. In both strains, the 4% KCl diet was associated with increased plasma renin-independent aldosterone production, as indicated by the marked increase of the aldosterone-to-renin ratios (from 1.4 +/- 0.3 to 9 +/- 3 in WKY and from 3 +/- 1 to 14 +/- 5 in SHR; P < 0.002). We conclude that an increase of StAR mRNA levels within the outer cortex is involved in the long-term adrenal response to potassium. This increase alone is not sufficient to increase aldosterone production in the presence of normal Cyp11b2 mRNA levels.
authors.affiliation: Dept. of Physiology, Univ. of Greifswald, Greifswalder Str. 11 C, 17495 Karlsburg, Germany. bspeters@gmx.de
authors.forename: Barbara
authors.initials: B
authors.lastname: Peters
authors.forename: Philipp
authors.initials: P
authors.lastname: Teubner
authors.forename: Susanne
authors.initials: S
authors.lastname: Clausmeyer
authors.forename: Tanja
authors.initials: T
authors.lastname: Puschner
authors.forename: Christiane
authors.initials: C
authors.lastname: Maser-Gluth
authors.forename: Hans-Josef
authors.initials: HJ
authors.lastname: Wrede
authors.forename: Bettina
authors.initials: B
authors.lastname: Kränzlin
authors.forename: Jörg
authors.initials: J
authors.lastname: Peters
mesh_terms: D000302:Adrenal Cortex / Q000378:metabolism; D000450:Aldosterone / Q000097:blood*; D000818:Animals; D001835:Body Weight; D019405:Cytochrome P-450 CYP11B2 / Q000378:metabolism; D004032:Diet; D015870:Gene Expression; D017403:In Situ Hybridization; D008297:Male; D010750:Phosphoproteins / Q000378:metabolism*; D011188:Potassium / Q000097:blood / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012083:Renin / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013995:Time; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D010750:Phosphoproteins; D012333:RNA, Messenger; D000098682:Steroidogenic Acute Regulatory Protein; D000450:Aldosterone; D019405:Cytochrome P-450 CYP11B2; D012083:Renin; D011188:Potassium