Vascular relaxation to omega-3 fatty acids: comparison to sodium nitroprusside, nitroglycerin, papaverine, and D600.
The vasorelaxant activity of the omega-3 fatty acids--docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids--in comparison with other known vasodilators--sodium nitroprusside, nitroglycerin, papaverine, and D600--were studied in the isolated rat aorta. The relaxant responses of these vasodilators and fatty acids at concentrations of 1-100 microM were assessed in aortic rings contracted with norepinephrine (NE 10(-6) M) or with KCl (30 mM). Cyclic nucleotide enhancers (sodium nitroprusside, nitroglycerin, papaverine) were more effective in producing relaxation, regardless of the contractile mechanism, i.e., alpha-adrenoceptor stimulation or depolarization. In contrast, the omega-3 fatty acids produced augmented relaxation in NE-contracted vessels. Relaxations produced by DHA (15 +/- 2% to 45 +/- 10%) were similar to D600 (16 +/- 2% to 60 +/- 7%) in NE-contracted rings, but not in KCl contracted rings. The responses to D600 and DHA in KCl-contracted vessels were 79 +/- 2% to 104 +/- 3% and 5 +/- 1% to 21 +/- 3%, respectively. In another set of experiments, the effects of omega-3 fatty acids in the presence of albumin were examined; no significant differences in the induced relaxant responses were noted. These results suggest that the mechanisms of vascular relaxation, such as cyclic nucleotide elevation and calcium antagonism of potential-operated channels, are different from those induced by the omega-3 fatty acids.
Engler
M B
MB
Department of Physiological Nursing, University of California, San Francisco 94143-0610.
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D004281:Docosahexaenoic Acids / Q000494:pharmacology; D015118:Eicosapentaenoic Acid / Q000494:pharmacology; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D005711:Gallopamil / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D005996:Nitroglycerin / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D010208:Papaverine / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000494:pharmacology
D015525:Fatty Acids, Omega-3; D014665:Vasodilator Agents; D009599:Nitroprusside; D004281:Docosahexaenoic Acids; D005711:Gallopamil; D011189:Potassium Chloride; D015118:Eicosapentaenoic Acid; D010208:Papaverine; D005996:Nitroglycerin; D009638:Norepinephrine