Acinar lumen pH regulates endocytosis, but not exocytosis, at the apical plasma membrane of pancreatic acinar cells

European Journal of Cell Biology
S D FreedmanG A Scheele

Abstract

A two-step exocytosis/endocytosis protocol was used in rat pancreatic acini to study membrane trafficking events at the apical plasma membrane (APM) as a function of extracellular pH. Exocytosis, as measured by cholecystokinin (CCK)-8-induced release of amylase into the incubation medium, was relatively insensitive to changes in extracellular pH from 5.5 to 9.0. In contrast, endocytosis, as measured by temperature-dependent uptake of horseradish peroxidase (HRP), was robust at pH values between 6.5 and 8.3 but abolished at acidic pH values of 5.5 to 6.0. Energy metabolism and cell viability were maintained during pH 6-induced cessation of HRP uptake, and the vesicular block could be reversed upon raising the luminal pH to 7.4. Histochemical and morphometric studies of HRP uptake examined by electron microscopy indicated that extracellular pH regulates endocytosis at the apical plasma membrane. At pH 6.0 in prestimulated cells, HRP uptake at the APM was abolished, and acinar lumen membranes remained markedly dilated with decreased density of microvilli and "arrested" exocytic images. At pH 7.4, HRP was taken up into endolysosomal structures within the Golgi complex, and acinar lumen membranes were contracted. Cleavage of GP2, a ...Continue Reading

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Citations

Jul 16, 2008·Current Gastroenterology Reports·Michael Wilschanski
Jul 27, 2002·Journal of Pediatric Gastroenterology and Nutrition·Michael O Stormon, Peter R Durie
Apr 19, 2002·Pancreas·Benjamin A FritzAnson W Lowe
Apr 21, 2007·Gut·Michael Wilschanski, Peter R Durie
Mar 14, 2002·Biochemical and Biophysical Research Communications·Vittorio RicciEnrico Solcia
Aug 18, 2004·Biochemical and Biophysical Research Communications·Su YuAnson W Lowe
Feb 24, 2004·American Journal of Physiology. Gastrointestinal and Liver Physiology·Diana D H ThomasGuy E Groblewski
Oct 3, 2006·The Journal of Biological Chemistry·Xuefeng SuHong-Long Ji
Aug 15, 2002·American Journal of Physiology. Cell Physiology·Frank Thévenod
Nov 22, 2002·American Journal of Physiology. Cell Physiology·Hiroaki SatohGeorge Seki
Oct 23, 2001·American Journal of Physiology. Gastrointestinal and Liver Physiology·T GreeleyM Soleimani
Jan 14, 1999·The American Journal of Physiology·H ShumakerM Soleimani
Sep 15, 2001·American Journal of Physiology. Gastrointestinal and Liver Physiology·R C De LisleC U Cotton
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Dec 31, 2002·Biochemical and Biophysical Research Communications·Frank ThévenodCatherine M Fuller
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Dec 11, 2019·Langmuir : the ACS Journal of Surfaces and Colloids·Rini MajumderPartha Pratim Parui

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