Effect of alpha-alpha diaspirin crosslinked hemoglobin (DCLHb) on the potency of sodium nitroprusside and nitroglycerine to decrease blood pressure in rats: a dose-response study.

The nitrovasodilators, sodium nitroprusside and nitroglycerine, effect a dose-dependent decrease in mean arterial blood pressure (MABP) by liberating nitric oxide. Alpha-alpha diaspirin crosslinked hemoglobin (DCLHb) is known to bind nitric oxide. We studied the effect of DCLHb on the potency of sodium nitroprusside (n=36) and nitroglycerine (n=36) to decrease MABP in rats which received 1, 10, 100, 1,000, or 10,000 mg/kg of the DCLHb, or normal saline as the Control. Six doses of sodium nitroprusside or nitroglycerine were given to each rat in a systematically varied sequence. For both drugs, in rats given 1, 10, or 100 mg/kg of DCLHb there were no between groups differences in the change in MABP compared to the Control group. For rats that received 1,000 or 10,000 mg/kg of DCLHb, the potency of nitroglycerine and sodium nitroprusside to decrease MABP was less (p<0.05) than the other groups. These data support the hypothesis that small doses of DCLHb effect a minimal change in the potency of nitrovasodilators to reduce blood pressure. However, they suggest that clinically relevant doses of DCLHb attenuate the vasodilatory ability of sodium nitroprusside and nitroglycerine.