Abstract
Increased fluid viscosity of a solution of hemoglobin-based oxygen carriers (HBOCs) reduces vasoconstrictive effects because increased shear stress on the vascular wall enhances the production of vasorelaxation factors such as NO. Nevertheless, on a microcirculatory level, it remains unclear how viscosity affects the reaction of HBOCs and NO. In this study, different HBOCs were perfused through narrow gas-permeable tubes (25μm inner diameter at 1mm/s centerline velocity; hemoglobin concentration [Hb]=5g/dL). The reaction was examined microscopically based on the Hb visible-light absorption spectrum. When immersed in a NO atmosphere, the NO-binding of deoxygenated Hb solution (viscosity, 1.1cP at 1000s-1) in the tube occurred about twice as rapidly as that of red blood cells (RBCs): 1.6cP. Binding was reduced by PEGylation (PEG-Hb, 7.7cP), by addition of a high molecular weight hydroxyethyl starch (HES) (2.8cP), and by encapsulation to form Hb-vesicles (HbVs, 1.5cP; particle size 279nm). However, the reduction was not as great as that shown for RBCs. A mixture of HbVs and HES (6.2cP) showed almost identical NO-binding to that of RBCs. Higher viscosity and particle size might reduce lateral diffusion when particles are flowing. The HbVs with HES showed the slowest NO-binding. Furthermore, Hb encapsulation and PEGylation, but not HES-addition, tended to retard CO-binding. Increased viscosity reportedly enhances production of endothelium NO. In addition, our results show that the increased viscosity also inhibits the reaction with NO. Each effect might mitigate vasoconstriction.
| Original language | English |
|---|---|
| Pages (from-to) | 169-176 |
| Number of pages | 8 |
| Journal | Microvascular Research |
| Volume | 81 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2011 Mar |
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Keywords
- Artificial oxygen carrier
- Gas reaction
- Hemoglobin
- Nitric oxide
- Rheology
ASJC Scopus subject areas
- Biochemistry
- Cardiology and Cardiovascular Medicine
- Cell Biology
Cite this
Increased viscosity of hemoglobin-based oxygen carriers retards NO-binding when perfused through narrow gas-permeable tubes. / Sakai, Hiromi; Okuda, Naoto; Takeoka, Shinji; Tsuchida, Eishun.
In: Microvascular Research, Vol. 81, No. 2, 03.2011, p. 169-176.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Increased viscosity of hemoglobin-based oxygen carriers retards NO-binding when perfused through narrow gas-permeable tubes
AU - Sakai, Hiromi
AU - Okuda, Naoto
AU - Takeoka, Shinji
AU - Tsuchida, Eishun
PY - 2011/3
Y1 - 2011/3
N2 - Increased fluid viscosity of a solution of hemoglobin-based oxygen carriers (HBOCs) reduces vasoconstrictive effects because increased shear stress on the vascular wall enhances the production of vasorelaxation factors such as NO. Nevertheless, on a microcirculatory level, it remains unclear how viscosity affects the reaction of HBOCs and NO. In this study, different HBOCs were perfused through narrow gas-permeable tubes (25μm inner diameter at 1mm/s centerline velocity; hemoglobin concentration [Hb]=5g/dL). The reaction was examined microscopically based on the Hb visible-light absorption spectrum. When immersed in a NO atmosphere, the NO-binding of deoxygenated Hb solution (viscosity, 1.1cP at 1000s-1) in the tube occurred about twice as rapidly as that of red blood cells (RBCs): 1.6cP. Binding was reduced by PEGylation (PEG-Hb, 7.7cP), by addition of a high molecular weight hydroxyethyl starch (HES) (2.8cP), and by encapsulation to form Hb-vesicles (HbVs, 1.5cP; particle size 279nm). However, the reduction was not as great as that shown for RBCs. A mixture of HbVs and HES (6.2cP) showed almost identical NO-binding to that of RBCs. Higher viscosity and particle size might reduce lateral diffusion when particles are flowing. The HbVs with HES showed the slowest NO-binding. Furthermore, Hb encapsulation and PEGylation, but not HES-addition, tended to retard CO-binding. Increased viscosity reportedly enhances production of endothelium NO. In addition, our results show that the increased viscosity also inhibits the reaction with NO. Each effect might mitigate vasoconstriction.
AB - Increased fluid viscosity of a solution of hemoglobin-based oxygen carriers (HBOCs) reduces vasoconstrictive effects because increased shear stress on the vascular wall enhances the production of vasorelaxation factors such as NO. Nevertheless, on a microcirculatory level, it remains unclear how viscosity affects the reaction of HBOCs and NO. In this study, different HBOCs were perfused through narrow gas-permeable tubes (25μm inner diameter at 1mm/s centerline velocity; hemoglobin concentration [Hb]=5g/dL). The reaction was examined microscopically based on the Hb visible-light absorption spectrum. When immersed in a NO atmosphere, the NO-binding of deoxygenated Hb solution (viscosity, 1.1cP at 1000s-1) in the tube occurred about twice as rapidly as that of red blood cells (RBCs): 1.6cP. Binding was reduced by PEGylation (PEG-Hb, 7.7cP), by addition of a high molecular weight hydroxyethyl starch (HES) (2.8cP), and by encapsulation to form Hb-vesicles (HbVs, 1.5cP; particle size 279nm). However, the reduction was not as great as that shown for RBCs. A mixture of HbVs and HES (6.2cP) showed almost identical NO-binding to that of RBCs. Higher viscosity and particle size might reduce lateral diffusion when particles are flowing. The HbVs with HES showed the slowest NO-binding. Furthermore, Hb encapsulation and PEGylation, but not HES-addition, tended to retard CO-binding. Increased viscosity reportedly enhances production of endothelium NO. In addition, our results show that the increased viscosity also inhibits the reaction with NO. Each effect might mitigate vasoconstriction.
KW - Artificial oxygen carrier
KW - Gas reaction
KW - Hemoglobin
KW - Nitric oxide
KW - Rheology
UR - http://www.scopus.com/inward/record.url?scp=79651471337&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79651471337&partnerID=8YFLogxK
U2 - 10.1016/j.mvr.2010.12.002
DO - 10.1016/j.mvr.2010.12.002
M3 - Article
VL - 81
SP - 169
EP - 176
JO - Microvascular Research
JF - Microvascular Research
SN - 0026-2862
IS - 2
ER -