Differential regulation of renal cyclooxygenase mRNA by dietary salt intake.
Experiments were done to investigate the influence of dietary salt intake on renal cyclooxygenase (COX) I and II mRNA levels. To this end rats were fed either a low NaCl diet (LS; 0.02% NaCl wt/wt) or a high NaCl diet (HS diet; 4% NaCl wt/wt) for 5, 10 and 20 days. After 10 days Na excretion differed 760-fold, plasma renin activity and renin mRNA were increased eight- and threefold in LS compared to HS animals. Total renal COX I mRNA decreased 50% following the LS diet and did not change after the HS diet. Conversely, COX II mRNA declined after HS intake and transiently increased after salt depletion. COX I and II mRNAs were unevenly distributed along the cortical-medullary axis with ratios of the cortex:outer medulla:papilla of 1:3:23 and 1:1:2, respectively. Cortical COX mRNAs were inversely regulated by salt intake with eightfold changes in COX II. Conversely, in medullary zones, COX I mRNA correlated directly with salt intake. We conclude that dietary salt intake influences renal cyclooxygenase mRNAs zone-specifically with opposite responses between cortex and medulla. Cortical COX II-mediated prostaglandin formation is probably important in low salt states whereas medullary COX I-produced prostaglandins seem to be more important for renal adaptation to a high salt intake.
Jensen
B L
BL
Institute of Physiology I, University of Regensburg, Germany. boye.jensen@vkl.uni-regensburg.de
Kurtz
A
A
D000818:Animals; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics*; D007668:Kidney / Q000201:enzymology*; D008297:Male; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
D007527:Isoenzymes; D012333:RNA, Messenger; D017673:Sodium Chloride, Dietary; D011451:Prostaglandin-Endoperoxide Synthases