AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 3 421-G429, Copyright © 1986 by American Physiological Society
Characteristics of rat pancreatic zymogen granules prepared by different methods
C. Niederau, J. H. Grendell and S. S. Rothman
Zymogen granules isolated from tissue homogenates by differential
centrifugation in isotonic sucrose solutions show substantial release of
digestive enzyme when suspended in isotonic NaCl and in sucrose solutions
at pH values above neutrality. A recent study reported a new method for
isolating granules, involving the use of a complex homogenization medium
and a Percoll gradient that was claimed to produce "stable" granules, i.e.,
granules that do not release their content in salt solutions and at pH
values at or above neutrality. In the present study, we compare granules
prepared in both ways, particularly in terms of their tendency to release
amylase in isotonic ionic solutions and as a function of pH. The relative
absence of amylase release from granules isolated by the new technique was
found to be attributable to simple differences in the details of the
experimental procedures that were used and not to actual differences in the
characteristics of the two granule preparations. For example, previous
studies with granules prepared in sucrose solutions reported substantial
salt-induced release at 37 degrees C, whereas the recent study reporting
the absence of salt-induced release from granules obtained from a Percoll
gradient was done at 24 degrees C. Under the identical experimental
conditions as used in the present study, little amylase release was seen at
24 degrees C for granules isolated by either technique, but substantial
release was seen for both at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
