The inhibitory effects of cellular and acellular hemoglobin (Hb) solutions on endothelium-dependent vasorelaxation were investigated in rabbit aortic strips. The tissues were precontracted with phenylephrine, after which acetylcholine (ACh) was added to induce a steady-state relaxation. All Hb solutions cumulatively reversed ACh-induced relaxation; liposome-encapsulated Hb and washed human red cells as cellular Hb reached a maximal vasconstriction at 1 mg/ml, while 2,3-diphosphoglycerae depleted Hb and pyridoxylated Hb as acellular Hb reached a plateau at 10 μg/ml. On the other hand, increases in oxygen affinity by pyridoxylation had little effect on this. These findings suggest that the cellularity is a very important factor influencing EDRF inhibition, and that acellular Hbs are more potent vasoconstrictors than cellular Hbs by a factor of about one hundred.
|Number of pages||4|
|Journal||Japanese Journal of Artificial Organs|
|Publication status||Published - 1994 Jan 1|
- blood substitutes
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