Inhibition of cyclooxygenase-2 in the rat renal medulla leads to sodium-sensitive hypertension.
Cyclooxygenase-2 expression in the renal medulla is regulated by dietary salt intake. The present study was performed to determine the influence of chronic inhibition of medullary cyclooxygenase-2 on arterial blood pressure in conscious Sprague-Dawley rats maintained on a high-salt (4% NaCl) or a low-salt (0.4% NaCl) diet. Rats were uninephrectomized and instrumented with femoral arterial and femoral vein or renal medullary interstitial catheters. Each rat received a continuous medullary or intravenous infusion of saline (0.5 mL per hour) for 3 control days, followed by infusion of the cyclooxygenase-2 inhibitor NS-398 (10 mg/kg per day) for 5 days. Medullary interstitial infusion of NS-398 significantly increased mean arterial pressure in the 4% NaCl group from 126+/-2 to 146+/-2 mm Hg (n=6) but did not alter blood pressure in the 0.4% NaCl group (n=6). Intravenous infusion of NS-398 to rats on the 4.0% NaCl diet also failed to alter mean arterial pressure (n=5). To test the blood pressure effect of a mechanistically different inhibitor of cyclooxygenase-2, an antisense oligonucleotide against cyclooxygenase-2 (18-mer; 8 nmol per hour) was infused into the renal medulla of rats maintained on a high-salt diet. Administration of the antisense oligonucleotide reduced cyclooxygenase-2 immunoreactive protein by 36% and significantly increased mean arterial pressure from 127+/-2 to 147+/-2 mm Hg (n=6). Renal medullary interstitial infusion of a scrambled oligonucleotide did not alter arterial pressure (n=5). These results demonstrate the importance of cyclooxygenase-2 in the renal medulla in maintaining blood pressure during high-salt intake.
Zewde
Tewabech
T
Department of Physiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Mattson
David L
DL
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D006973:Hypertension / Q000209:etiology*; D007679:Kidney Medulla / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D009578:Nitrobenzenes / Q000494:pharmacology; D020319:Oligodeoxyribonucleotides, Antisense; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage; D013449:Sulfonamides / Q000494:pharmacology
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D009578:Nitrobenzenes; D020319:Oligodeoxyribonucleotides, Antisense; D017673:Sodium Chloride, Dietary; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases