Nitrate tolerance is specific for nitric acid esters and its recovery requires an intact protein synthesis.
Using cultured LLC-PK1 cells the present study investigates mechanisms leading to nitrate tolerance and its reversal. A 5-h pretreatment with glyceryl trinitrate (GTN, 0.01-100 microM) resulted in desensitization of the intracellular cyclic GMP response to a subsequent 10-min challenge with GTN (1 microM). The spontaneous donor of nitric oxide (NO) spermine NONOate, which releases NO independently of enzymatic catalysis, did not induce tolerance to its own cyclic GMP stimulatory effect and remained fully effective in GTN-tolerant cells. Tolerant cells regained sensitivity to GTN after a 30-h incubation in media. Recovery of the cyclic GMP response was blocked in the presence of cycloheximide (10 microM) suggesting that de novo protein synthesis is necessary for tolerance reversal. Our results demonstrate that nitrate tolerance is specific for nitric acid esters and possibly due to down-regulation of enzymes involved in bioactivation of, and NO generation from, organic nitrates.
Hinz
B
B
Department of Pharmacology and Toxicology, School of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, Halle (Saale), 06099, Germany.
Schröder
H
H
D000818:Animals; D002460:Cell Line; D006152:Cyclic GMP / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D007700:Kinetics; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009589:Nitrogen Oxides; D005996:Nitroglycerin / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D014176:Protein Biosynthesis; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D014665:Vasodilator Agents; C091861:spermine nitric oxide complex; D009599:Nitroprusside; D013096:Spermine; D009569:Nitric Oxide; C002385:linsidomine; D003513:Cycloheximide; D008981:Molsidomine; D005996:Nitroglycerin; D006152:Cyclic GMP