Acellular and cellular hemoglobin solutions as vasoconstrictive factor.
The inhibitory effects of acellular and cellular hemoglobin (Hb) solutions on endothelium-dependent vasorelaxation were investigated in rabbit thoracic aortic strips. As acellular Hb solutions, 2,3-diphosphoglycerate (DPG)-depleted Hb and pyridoxylated Hb were examined. Cellular Hb solutions included washed human fresh red cells and liposome Hb encapsulated with pyridoxal-5'-phosphate (PLP). The tissues were precontracted with phenylephrine (PE), after which acetylcholine (ACh) was added to elicit a steady-state relaxation. Acellular Hb solutions cumulatively reversed ACh-induced relaxation, and these inhibitory effects reached a plateau at 10 micrograms/ml. Increasing oxygen affinity by pyridoxylation had little effect on this. In contrast, both red cells and liposome Hb solution showed moderate inhibitory effects, and they reached a plateau at 1 mg/ml. These findings indicate that acellular Hb solutions are more potent inhibitors than cellular Hb solutions by a factor of about 100, and that the encapsulation of Hb is a preferable method to mimic the red cell.
Nakai
K
K
Hokkaido Red Cross Blood Center, Sapporo, Japan.
Matsuda
N
N
Amano
M
M
Ohta
T
T
Tokuyama
S
S
Akama
K
K
Kawakami
Y
Y
Tsuchida
E
E
Sekiguchi
S
S
D019794:2,3-Diphosphoglycerate; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001802:Blood Substitutes / Q000494:pharmacology*; D003911:Dextrans / Q000494:pharmacology; D004163:Diphosphoglyceric Acids / Q000302:isolation & purification; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D006454:Hemoglobins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008081:Liposomes; D008297:Male; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D011817:Rabbits; D012996:Solutions; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology
D001802:Blood Substitutes; D003911:Dextrans; D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D008081:Liposomes; D012996:Solutions; C040953:dextran-hemoglobin complex (deoxygenated); C030939:polyhemoglobin-pyridoxal-5-phosphate; D019794:2,3-Diphosphoglycerate; D011732:Pyridoxal Phosphate; D000109:Acetylcholine