Oxygen transfer from single microvessels to acinar cellsin
secretin-stimulated pancreas of rat.
Seiyama, Akitoshi, Satonori Tanaka, Hiroaki Kosaka, and Takeshi Shiga.
Department of Physiology, Osaka University, Medical School, 2-2
Yamadaoka, Suita, Osaka 565, JAPAN
APStracts 2:0491H, 1995.
O2 transfer from inside to outside of single microvessels in resting
and secretin-stimulated exocrine pancreas of rats was investigated by
dual-spot microspectroscopy. Measurements of intravascular hemoglobin
(Hb) concentration, O2 saturation of Hb, and velocity of flowing red
blood cells (RBCs) were carried out in the single microvessels at the
edge of the exocrine pancreas of anesthetized rats. Rate of O2
release (RO2) from single microvessel wall was constant [ca. 2
nmol/cm2/sec] over a wide range of oxyhemoglobin inflow ([HbO2]
inflow = 200??700 fmol/ sec), but decreased almost linearly with the
[HbO2] inflow below 200 fmol/sec, where the [HbO2] inflow is defined
as a product of inflowing oxyhemoglobin concentration and blood flow
rate. When the exocrine pancreas was stimulated with secretin either
by superfusion (> 0.3 nM) or by intravenous infusion (> 0.5
ug/kg/hr), RO2 as well as pancreatic secretion increased about 2
times higher than those of the basal values. With secretin
administration, it was found that (1) an inverse relationship between
RBC velocity and intravascular Hb concentration was held, and thus
(2) [HbO2] inflow was maintained within the basal level (i.e., 200
700 fmol/sec). Further, (3) the elevation of O2 release from single
microvessels was accomplished by the increased O2 extraction instead
of the increased O2 supply in the microvessels.
Received 11 July 1995; accepted in final form 26 October 1995.
APS Manuscript Number H638-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95