Jmb. Newman et al., Nutritive blood flow affects microdialysis O/I ratio for [C-14] ethanol and 3H(2)O in perfused rat hindlimb, AM J P-HEAR, 281(6), 2001, pp. H2731-H2737
Citations number
38
Categorie Soggetti
Cardiovascular & Hematology Research
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
Changes in the microdialysis outflow-to-inflow (O/I) ratio for [C-14] ethan
ol and (H2O)-H-3 were determined in the perfused rat hindlimb after increas
es and decreases in nutritive flow mediated by the vasoconstrictors norepin
ephrine (NE) and serotonin (5-HT), respectively. Microdialysis probes (cont
aining 10 mM [C-14] ethanol and (H2O)-H-3 pumped at 1 or 2 ml/min) were ins
erted through the calf of the rat. Hindlimb perfusion flow rate was varied
from 6 to 56 ml.min(-1).100 g(-1) in the presence of NE, 5-HT, or saline ve
hicle. The O/I ratios for both tracers were determined at each perfusion fl
ow rate, as was perfusion pressure, oxygen uptake (a surrogate indicator of
nutritive flow), and lactate release. Both tracers showed a decreased O/I
ratio as hindlimb perfusion flow was increased, with [C-14] ethanol being h
igher than (H2O)-H-3. NE decreased the O/I ratio compared with vehicle, and
5-HT increased it for both tracers and both microdialysis flow rates. We c
onclude that the microdialysis O/I ratio, while able to detect changes in t
otal flow, is also sensitive to changes in nutritive and nonnutritive flow,
where the latter still extracts tracer, but less than the former.