| Item type: | Article | ||||
|---|---|---|---|---|---|
| Journal or Publication Title: | Kidney International | ||||
| Publisher: | BLACKWELL SCIENCE INC | ||||
| Place of Publication: | MALDEN | ||||
| Volume: | 59 | ||||
| Number of Issue or Book Chapter: | 1 | ||||
| Page Range: | pp. 62-68 | ||||
| Date: | 2001 | ||||
| Institutions: | Medicine > Lehrstuhl für Innere Medizin II Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Armin Kurtz | ||||
| Identification Number: |
| ||||
| Keywords: | RENIN SECRETION; RENOVASCULAR HYPERTENSION; PROSTAGLANDIN SYNTHESIS; INHIBITION; KIDNEY; RNA; thick ascending limb of Henle; salt transport; renin; cell signaling; diuretics; juxtaglomerular apparatus | ||||
| Dewey Decimal Classification: | 500 Science > 570 Life sciences 600 Technology > 610 Medical sciences Medicine | ||||
| Status: | Published | ||||
| Refereed: | Yes, this version has been refereed | ||||
| Created at the University of Regensburg: | Yes | ||||
| Item ID: | 73933 |
Web of ScienceAbstract
Background. During a low salt intake, maintenance of renal blood flow and renin secretion depends on intact formation of prostaglandins. In the juxtaglomerular apparatus, the inducible isoform of cyclooxygenase, cyclooxygenase-2 (COX-2), is restricted to the macula densa and the cortical thick ascending limb of Henle (cTALH) cells, and is inversely regulated by dietary salt intake. This study ...
Abstract
Background. During a low salt intake, maintenance of renal blood flow and renin secretion depends on intact formation of prostaglandins. In the juxtaglomerular apparatus, the inducible isoform of cyclooxygenase, cyclooxygenase-2 (COX-2), is restricted to the macula densa and the cortical thick ascending limb of Henle (cTALH) cells, and is inversely regulated by dietary salt intake. This study aimed to elucidate whether the effect of NaCl on macula densa COX-2 expression is mediated by transepithelial transport of NaCl. Methods. To this end, male Sprague-Dawley rats received subcutaneous infusions of the loop diuretic furosemide (12 mg/ day) or were fed with the diuretic hydrochlorothiazide (30 mg/kg day) for seven days each. To compensate for their salt and water loss, the animals had free access to normal water and to salt water (0.9% NaCl, 0.1% KCl). COX-2 expression in kidney cortex was assessed by immunohistochemical staining and by semiquantitative ribonuclease protection assay for COX-2 mRNA. Results. After six days of furosemide infusion to salt-substituted rats, there was no change of extracellular volume. Furosemide led to a fivefold and threefold increase of plasma renin activity and renocortical renin mRNA level, respectively. In parallel, there was a threefold increase of renocortical COX-2 abundance, while the COX-1 mRNA level remained unchanged. Moreover, the percentage of juxtaglomerular apparatuses immunopositive for COX-2 increased threefold in response to furosemide compared with vehicle-infused animals. Hydrochlorothiazide treatment increased plasma renin activity twofold but did not change kidney cortical renin mRNA, COX-2 mRNA, or COX-2 immunoreactivity. Conclusion. Our findings suggest that inhibition of salt transport in the loop of Henle, but not in the distal tubule, causes a selective stimulation of COX-2 expression in the macula densa region. This up-regulation may be of relevance for macula densa signaling, which links tubular salt transport rate with glomerular filtration rate and renin secretion.
Metadata last modified: 19 Dec 2024 15:54
Altmetric