Interpretation of near-infrared spectroscopy signals: a study with a newly developed perfused rat brain model.
Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret near-infrared spectroscopy signals. Changes in CBF and total hemoglobin (tHb) were in parallel, although tHb showed no change when changes in CBF were small (< or =10%). Increasing CBF caused an increase in oxygenated hemoglobin (HbO(2)) and a decrease in deoxygenated hemoglobin (deoxy-Hb). Decreasing CBF was accompanied by a decrease in HbO(2), whereas changes in direction of deoxy-Hb were various. Cerebral blood congestion caused increases in HbO(2), deoxy-Hb, and tHb. Administration of pentylenetetrazole without increasing the flow rate caused increases in HbO(2) and tHb with a decrease in deoxy-Hb. There were no significant differences in venous oxygen saturation before vs. during seizure. These results suggest that, in activation studies with near-infrared spectroscopy, HbO(2) is the most sensitive indicator of changes in CBF, and the direction of changes in deoxy-Hb is determined by the degree of changes in venous blood oxygenation and volume.
Hoshi
Y
Y
Biophysics Group, Research Institute for Electronic Science, Hokkaido University, Sapporo 060 - 0812, Japan. yhoshi@prit.go.jp
Kobayashi
N
N
Tamura
M
M
D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D006454:Hemoglobins / Q000378:metabolism; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism; D010433:Pentylenetetrazole / Q000494:pharmacology; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D013997:Time Factors
D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen; D010433:Pentylenetetrazole