AJP - Gastrointestinal and Liver Physiology, Vol 243, Issue 2 155-G171, Copyright © 1982 by American Physiological Society
Validity of iodoantipyrine clearance for measuring gastrointestinal tissue blood flow
M. C. Dugas and R. L. Wechsler
Simultaneous determinations of 1) the clearance (mF) of 4-iodoantipyrine
(IAP) and tritiated water, 2) the mF of IAP and total circulating tissue
blood volume, 3) the mF of IAP and either 15- or
25-micrometers-diam-microsphere-measured flow, and 4) 15- and
25-micrometers-diam-microsphere-measured flow were made on tissues from dog
gastrointestinal tracts. Results show the mF of IAP equals or exceeds that
of tritiated water in all tissue layers, and tissue blood volume does not
affect the measurement of the IAP mF. Perfusion of the gastrointestinal
wall exhibits macroscopic heterogeneity due to differences in perfusion of
the three tissue layers, but an effect of microscopic heterogeneity on
tissue mF assessment was not apparent. Composite total-wall IAP mF was not
significantly different from 25-micrometers-microsphere total-wall flow and
was identical to this flow when colonic locations were omitted. Comparisons
of 15-micrometers-microsphere flow to IAP mF and to
25-micrometers-microsphere flow both indicated shunting of
15-micrometers-microspheres. Such shunting occurred predominantly through
submucosal and muscle layers. It is concluded that IAP clearance accurately
measures blood flow in gastrointestinal tissue.
