Fluorescent microspheres are superior to radioactive microspheres in chronic blood flow measurements.
The accuracy of the fluorescent (FM) and radioactive microsphere (RM) techniques is similar in acute experiments but has not been established in chronic experiments. In the present study various combinations (at least pairs) of FM and/or RM labels were injected simultaneously between 2 mo and 5 min before each animal was killed. Blood flow was determined in many organs. Intramethod mean difference and variation did not change over time for FM but increased significantly for RM (from 1.8 +/- 1.4 to 25.6 +/- 21.8% and from 4.4 +/- 3.2 to 32.4 +/- 23.0% at 5 min and 2 mo, respectively). Also the FM-RM intermethod mean difference and variation increased (from -0.5 +/- 8.5 to 40.8 +/- 23.8% and from 23. 6 +/- 4.6 to 71.8 +/- 34.3%, respectively). After 2 mo, blood flow estimations were 20-50% lower with the various RM, whereas brain and liver blood flow values varied even more between isotopes. Underestimation started within 1 day for 51Cr and within 2 wk for 141Ce, 95Nb, and 85Sr. We conclude that FM are superior to RM for blood flow determination in experiments lasting longer than 1 day, presumably because of leaching of isotopes from RM.
Van Oosterhout
M F
MF
Department of Physiology, Cardiovascular Research Institute Maastricht, University of Maastricht, 6200 MD Maastricht, The Netherlands.
Prinzen
F W
FW
Sakurada
S
S
Glenny
R W
RW
Hales
J R
JR
D000818:Animals; D001776:Blood Circulation Time / Q000379:methods; D002302:Cardiac Output; D002560:Cerebrovascular Circulation; D005456:Fluorescent Dyes; D008102:Liver Circulation; D008863:Microspheres; D009928:Organ Specificity; D011817:Rabbits; D011865:Radioisotope Dilution Technique; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012039:Regional Blood Flow; D012044:Regression Analysis; D015203:Reproducibility of Results; D013997:Time Factors
D005456:Fluorescent Dyes; D019275:Radiopharmaceuticals