CONTRACTILE EFFECTS OF DIASPIRIN CROSS-LINKED HEMOGLOBIN (DCLHB(TM)) ON ISOLATED PORCINE BLOOD-VESSELS

The effects of diaspirin cross-linked hemoglobin (DCLHb(TM)) on vascul ar tone were examined in arterial and venous rings isolated from mesen teric, renal, femoral, and pulmonary blood vessels. Rings were placed in organ baths at optimal passive tension in Krebs' solution (37 degre es C) and aerated with a mixture of 95% O-2/5% CO2. Vessels were treat ed with increasing concentrations of DCLHb or an iso-osmotic serum alb umin solution. Ail artery and vein rings contracted in the presence of DCLHb. With the exception of the pulmonary vein, the magnitude of the tension increase with DCLHb was greater in the arteries than in the v eins. Removal of the endothelium by scraping or the addition of a nitr ic oxide synthase inhibitor blocked the DCLHb-induced contraction in t he pulmonary artery and vein. DCLHb also significantly reduced basal c yclic guanosine-3-5'-monophosphate in the pulmonary vein. These studie s suggest that the constrictor activity of DCLHb is due primarily to i nhibition of basal nitric oxide-induced relaxation of the vascular smo oth muscle.