Effect of acetylcholine and calmodulin-inhibitor on o2 transfer
from exocrine pancreatic microvessels of rats.
Seiyama, Akitoshi, Hiroaki Kosaka, and Takeshi Shiga.
Department of Physiology, Osaka University, Medical School, 2-2
Yamadaoka, Suita, Osaka 565, JAPAN
APStracts 2:0547H, 1995.
Effects of acetylcholine (ACh) and calmodulin(CaM)-inhibitor, W-7, on
the rate of O2 release (RO2) from single exocrine pancreatic
microvessels of anesthetized rats were investigated with dual-spot
microspectroscopy. The surface of pancreas was superfused with Krebs
-Henseleit buffer containing various concentrations of ACh and/or W-7.
Superfusion of ACh (>20 uM) elevated RO2 as well as pancreatic
secretion ca. 2.5 times higher than that of control level, whereas
superfusion of W-7 (>100 uM) reduced ca. 50%. In both cases, O2
inflow in single microvessels, as quantified by oxyhemoglobin inflow
into the microvessels, was maintained at control level. On the other
hand, superfusion of both ACh and W-7 did not modify RO2 and
pancreatic secretion, in spite of significant reduction in O2 inflow.
These results indicate that 1) the ACh-induced elevation of O2
release from single microvessels is accomplished by the increased O2
extraction instead of the increased O2 inflow in the microvessels,
and 2) the activity of W-7 sensitive Ca2+-binding protein, most
likely CaM, is responsible for half of the microvascular O2 transfer
and of the pancreatic exocrine secretion.
Received 21 September 1995; accepted in final form 30 November
1995.
APS Manuscript Number H895-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95