title: Nisoldipine increases the bioavailability of endothelial NO.
abstract: Different observations suggest that dihydropyridine calcium antagonists alter endothelial NO release. Therefore, in a first step we investigated whether part of the nisoldipine (a dihydropyridine calcium antagonist with a possible selectivity for coronaries)-induced vasorelaxation was due to an NO release from the endothelium in porcine coronary arteries. Secondly, we directly measured whether nisoldipine increased NO release from rabbit aorta or the nisoldipine enantiomers (Bay R 1223, Bay R 1224) from rat aorta. Thirdly, we determined whether nisoldipine exerted antioxidative properties in segments of porcine aorta with intact endothelium. Blocking endothelial NO synthase with N-nitro-L-arginine resulted in a significant shift of the relaxation curve to higher concentrations. Accordingly, nisoldipine induced a concentration-dependent release of NO (direct electrochemical detection) from native endothelium which already started at a therapeutical level (1 nmol/l nisoldipine/6.5 +/- 1.2 nmol/l NO). To evaluate whether this effect was due to an antioxidative protection of NO, we examined the influence of nisoldipine on a hyperglycemia (30 mmol/l, 20 min)-induced reactive oxygen species release of vascular endothelium from porcine coronary arteries. Nisoldipine concentration-dependently reduced the reactive oxygen species release (>50%; 10 micromol/l). Moreover, a carbachol-induced NO release (rabbit aorta) which was significantly diminished by hyperglycemia was completely restored in the presence of nisoldipine (3 micromol/l). We conclude that nisoldipine increases the NO bioavailability which may result in an ameliorated endothelial function.
authors.affiliation: Institute of Pharmacology, University of Cologne, Germany. Reinhard.Berkels@medizin.uni-koeln.de
authors.forename: R
authors.initials: R
authors.lastname: Berkels
authors.forename: R
authors.initials: R
authors.lastname: Roesen
authors.forename: H
authors.initials: H
authors.lastname: Bartels
authors.forename: S
authors.initials: S
authors.lastname: Purol-Schnabel
authors.forename: I
authors.initials: I
authors.lastname: Kirmiziguel
authors.forename: H
authors.initials: H
authors.lastname: Farmer
authors.forename: G V
authors.initials: GV
authors.lastname: Born
authors.forename: W
authors.initials: W
authors.lastname: Klaus
mesh_terms: D000818:Animals; D001682:Biological Availability; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D015737:Nisoldipine / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009924:Organ Culture Techniques; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D013552:Swine; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D009573:Nitrites; D017382:Reactive Oxygen Species; D014665:Vasodilator Agents; D009569:Nitric Oxide; D015737:Nisoldipine