AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 2 569-R575, Copyright © 1995 by American Physiological Society
H2 gas clearance technique for separating rat uterine blood flow into endometrial and myometrial components
R. S. Zhang, P. H. Guth, O. U. Scremin and G. Chaudhuri
Department of Obstetrics and Gynecology, University of California, Los Angeles.
The H2 gas clearance technique was employed to measure uterine blood flow
(UBF) in ovariectomized rats. A needle-type platinum electrode (125 microns
diam) was inserted into the rat uterine wall to measure the tissue blood
flow surrounding the electrode. The electrode can be placed in individual
layers of the uterus to measure the endometrial blood flow (EBF) or the
myometrial blood flow (MBF). By use of this technique, baseline EBF and MBF
were 37.8 +/- 3.53 (n = 21) and 47.2 +/- 4.56 (n = 5) ml.min-1.100 g-1,
respectively, with an EBF/MBF ratio of 0.8. Intravenous bolus injection of
17 beta-estradiol (1 microgram/kg) induced a significant increase in UBF.
Phenylephrine, an alpha-adrenergic receptor agonist, reduced UBF. In some
animals, a second platinum electrode was used to measure gastric mucosal
blood flow simultaneously with UBF. While 17 beta-estradiol selectively
increased UBF, pentagastrin selectively increased gastric mucosal blood
flow. To further validate the baseline UBF distribution between endometrial
and myometrial layers, iodo[14C]antipyrine autoradiography was employed.
With the iodo[14C]antipyrine technique, the EBF/MBF ratio was 0.91 +/- 0.07
(n = 5), which is similar to that obtained with the H2 gas clearance
technique.
