cosyntropin and Potassium-Deficiency

During potassium repletion of potassium-deficient rats, a marked rise in the adrenal zona glomerulosa content of cytochrome P-45011 beta mRNA preceded an extensive increase in corticosterone methyl oxidation (CMO) 1 and 2. Potassium intake did not substantially affect zona glomerulosa cytochrome P-450SCC or zona fasciculata-reticularis cytochrome P-45011 beta mRNA levels. We had previously shown that the induction of CMO 1 and 2 in the zona glomerulosa of potassium-repleted rats was associated with the appearance of a second form of cytochrome P-45011 beta with a lower molecular weight (49,000) than the major form of the enzyme (51,000). On the basis of the present observations, mRNAs encoding the two forms of the enzyme would be homologous and of similar length. Potassium intake thus controls the biosynthesis of the 49 kDa enzyme most likely at the level of transcription or, alternatively, by influencing mRNA stability.

Topics: Animals; Corticosterone; Cosyntropin; Enzyme Induction; Isoenzymes; Male; Potassium Chloride; Potassium Deficiency; Rats; RNA, Messenger; Steroid 11-beta-Hydroxylase; Zona Glomerulosa