Coordinate changes of renin and brain-type nitric-oxide-synthase (b-NOS) mRNA levels in rat kidneys

• Published in: Pflügers Archiv 1996-07, Vol.432 (3), p.394-400
• Main Authors: Schricker, K, Pötzl, B, Hamann, M, Kurtz, A
• Format: Article
• Language: English
• Subjects: Angiotensin II - metabolism; Angiotensin Receptor Antagonists; Animals; Atrial Natriuretic Factor - biosynthesis; Base Sequence; Brain - enzymology; Hypertension, Renovascular - enzymology; Kidney - drug effects; Kidney - enzymology; Male; Molecular Sequence Data; Nitric Oxide Synthase - biosynthesis; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; Renal Artery - physiology; Renin - metabolism; RNA, Messenger - biosynthesis
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/s004240050150

In our study we have examined the mRNA levels of nitric-oxide-(NO-)synthases in rat kidneys during states of stimulated and reduced renin gene expression, to find out whether renal mRNA levels of NO-synthases are correlated with the activity of the renin system. Stimulation of the renin system was achieved by unilateral renal artery clipping (2-kidney/1-clip rats), treatment with the angiotensin II (ANG II) antagonist losartan (40 mg/kg), application of furosemide (12 mg x kg-1 x day-1) and a low-sodium diet (0.02% w/w Na+), which increased renin mRNA levels to 464%, 495%, 309% and 219% of those of control animals, respectively. Inhibition of the renin system was achieved in the nonclipped (contralateral) kidneys of 2-kidney/1-clip rats and in the kidneys of rats which were fed a high-sodium diet (4% w/w Na+); in both cases renin mRNA levels decreased to about 50% of the control values. First screening of the gene expression of brain-type NO-synthase (b-NOS), endothelial NOS (e-NOS) and inducible NOS (i-NOS) during all these alterations of the renin system was done using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Results from such noncompetitive PCR experiments indicated that only b-NOS mRNA levels change concordantly with the levels of renin. These changes in b-NOS mRNA levels were checked by the more reliable method of RNase protection assay. Results of the RNase protection assay proved that the renal levels of b-NOS mRNA were significantly increased by about 50% after a low-sodium diet and hypoperfusion of the kidney. Given a stimulatory role of endothelium-derived relaxing factor (EDRF)/NO on the renin system our findings may provide the first evidence that increases of renal levels of b-NOS mRNA and, as a consequence, of renal EDRF/NO formation could be important mediators of the well-known effect of salt intake and hypoperfusion on the renin system.