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Functional properties of a new crosslinked hemoglobin designed for use as a red cell substitute
Author(s) -
Keipert P.E.,
Adeniran A.J.,
Kwong S.,
Benesch R.E.
Publication year - 1989
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1046/j.1537-2995.1989.29990070179.x
Subject(s) - chemistry , hemoglobin , bohr effect , tetramer , oxygen–haemoglobin dissociation curve , dissociation (chemistry) , p50 , in vivo , excretion , oxygen , biochemistry , organic chemistry , biology , microbiology and biotechnology , transcription factor , gene , enzyme
A new crosslinking agent, bis‐pyridoxal tetraphosphate, (bis‐PL)P 4 , was used to prevent dissociation of the hemoglobin (Hb) tetramer. Yields in excess of 75 percent of intramolecularly crosslinked (bis‐PL)P 4 Hb have been obtained using stoichiometric amounts of the crosslinking reagent. Some functional properties of (bis‐PL)P 4 Hb have been evaluated in vitro and in vivo. Oxygen affinity was substantially reduced (p50 = 31 torr at 37°C, pH 7.4, pCO 2 = 40 torr), while the Bohr coefficient was −0.27 of H + per mol of O 2 . Owing to its right‐shifted dissociation curve, (bis‐PL)P 4 Hb still yielded a p50 of 15 torr at a low temperature (16°C), as compared with only 3 torr for normal adult Hb (HbA). Clearance of (bis‐PL)P 4 Hb from plasma was significantly delayed (t½ = 171 min, at a dose of 0.2 g/kg of body weight compared with that of HbA (t½ = 54 min). Heart rate, mean arterial blood pressure, and respiration remained stable or returned to normal values within hours after bolus injection of the hemoglobin. The (bis‐PL)P 4 Hb was not excreted in the urine, in contrast to HbA (21% of the total dose of HbA appeared in the urine within the first 2 hrs). These results show that the covalent β‐β crosslink prevents the renal excretion of (bis‐PL)P 4 Hb, thereby significantly prolonging vascular retention. These properties, together with an increased ability to unload O 2 , make (bis‐PL)P 4 Hb a promising new candidate as a red cell substitute.