A method for reducing or preventing vasoactivity caused by administration of a composition comprising a hemoglobin oxygen carrier (HBOC), free hemoglobin (Hb), stored blood products characterized by vasoactivity-inducing concentrations of free tetrameric hemoglobin, and combinations thereof, comprising combining at least one inhibitor phosphodiesterase (PDE) with an additional agent selected from the group consisting of at least one calcium channel blocker from at least one alpha-en agonist and combinations thereof, with a material containing HBOC or Hb in an amount effective to reduce or prevent said vasoactivity. The method of claim 1, wherein said phosphodiesterase inhibitors are selected from the group consisting of 5- (2-propoxyphenyl) -1H- [1,2,3] triazolo [4, 5-d] pyrimidine-7 (4H) -one, 2-o-propoxyphenyl-8-azapurin-6-one, 1-cyclopentyl-3-methyl-6- (4-pyridyl) pyrazolo [3,4-d] pyrimidine-4- (5H) -one, SCH 48936 ((+) - 6a, 7,8,9,9a, 10,11,11a-octahydro-2,5-dimethyl-3H-pentane (6a, 1, 4,5-imidazo [2,1-b] purin-4 (5H) -one, 2-phenyl-8-ethoxycycloheptimidazole, 1- [6-chloro-4- (3,4-methylenedioxybenzyl) aminoquinazolin-2- yl] piperidine-4-carboxylate-sodium sesquihydrate, sildenafil, tadalafil, vardenafil, avanafil, lodenafil, mordenafil, udenafil, zaprinast, xanthine, caffeine, theophylline, theobromine, aminophylline, oestrifilin, diphylline, pentoxifylline, isobutylmethyl Santini dipyridamole, papaverine, and their smesey.3. The method of claim. 1, characterized in that said calcium channel blockers are selected from the group consisting of amlodipine, diltiazem, felodipine, isradipine, nifedipine, nicardipine, nimodipine, nisoldipine, verapamil and their mixtures. The method of claim 1, wherein said alpha agonists are selected from1. Способ снижения или предупреждения вазоактивности, вызванной введением композиции, содержащей носитель кислорода на основе гемоглобина (HBOC), свободного гемоглобина (Hb), хранящихся продуктов крови, характеризующихся вызывающими
