AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 5 539-R543, Copyright © 1985 by American Physiological Society
Transplacental diffusion and blood flow of gravid bovine uterus
L. P. Reynolds, C. L. Ferrell and S. P. Ford
Electromagnetic blood flow transducers and uterine arterial, uterine
venous, umbilical venous, fetal femoral arterial, and fetal femoral venous
catheters were implanted in 11 cows on day 161 +/- 4 of gestation.
Antipyrine (0.66 M) plus NaCl (0.16 M) dissolved in deuterium oxide (D2O),
or H2O, was infused at a constant rate into the fetal femoral vein
catheter. Concentrations of antipyrine and D2O in uterine arterial and
venous blood and antipyrine in fetal arterial and umbilical venous blood,
as well as middle uterine arterial blood flow (electromagnetic transducer),
were determined. Antipyrine and D2O gave similar estimates (steady-state
diffusion method) of gravid uterine blood flow. In addition, the slope of
the regression of D2O on antipyrine estimates was not different (P greater
than 0.10) from one. Electromagnetic transducers gave estimates of uterine
blood flow that were 32-42% of those obtained with steady-state diffusion
but were correlated (P less than 0.05) with estimates obtained by use of
both antipyrine and D2O. The transplacental clearance rate of antipyrine
was similar (per kg placenta) to that observed in ewes. It was suggested
that the maternal and fetal microvasculatures of the bovine placenta could
have a concurrent arrangement with vascular shunts or maldistribution of
flows, as has been suggested for the ewe.
