scholarly journals Exocytosis by vesicle crumpling maintains apical membrane homeostasis during exocrine secretion

2021 ◽  
Vol 56 (11) ◽  
pp. 1603-1616.e6
Author(s):  
Kumari Kamalesh ◽  
Nadav Scher ◽  
Tom Biton ◽  
Eyal D. Schejter ◽  
Ben-Zion Shilo ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Exocrine Secretion

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

Secretin-induced exocrine secretion in perfused pancreas isolated from diabetic rats

Diabetes ◽  
1988 ◽  
Vol 37 (9) ◽  
pp. 1173-1180 ◽  
Author(s):  
Y. Okabayashi ◽  
M. Otsuki ◽  
A. Ohki ◽  
T. Nakamura ◽  
S. Tani ◽  
...  
Keyword(s):  
Exocrine Secretion ◽  
Diabetic Rats ◽  
Perfused Pancreas

scholarly journals Gating of Na channels in the rat cortical collecting tubule: effects of voltage and membrane stretch.

1996 ◽  
Vol 107 (1) ◽  
pp. 35-45 ◽  
Author(s):  
L G Palmer ◽  
G Frindt
Keyword(s):  
Voltage Dependence ◽  
Single Channel ◽  
Apical Membrane ◽  
Na Channels ◽  
Patch Clamp Technique ◽  
Open Time ◽  
Collecting Tubule ◽  
Excised Patches ◽  
The Mean ◽  
Cortical Collecting Tubule

The gating kinetics of apical membrane Na channels in the rat cortical collecting tubule were assessed in cell-attached and inside-out excised patches from split-open tubules using the patch-clamp technique. In patches containing a single channel the open probability (Po) was variable, ranging from 0.05 to 0.9. The average Po was 0.5. However, the individual values were not distributed normally, but were mainly < or = 0.25 or > or = 0.75. Mean open times and mean closed times were correlated directly and inversely, respectively, with Po. In patches where a sufficient number of events could be recorded, two time constants were required to describe the open-time and closed-time distributions. In most patches in which basal Po was < 0.3 the channels could be activated by hyperpolarization of the apical membrane. In five such patches containing a single channel hyperpolarization by 40 mV increased Po by 10-fold, from 0.055 +/- 0.023 to 0.58 +/- 0.07. This change reflected an increase in the mean open time of the channels from 52 +/- 17 to 494 +/- 175 ms and a decrease in the mean closed time from 1,940 +/- 350 to 336 +/- 100 ms. These responses, however, could not be described by a simple voltage dependence of the opening and closing rates. In many cases significant delays in both the activation by hyperpolarization and deactivation by depolarization were observed. These delays ranged from several seconds to several tens of seconds. Similar effects of voltage were seen in cell-attached and excised patches, arguing against a voltage-dependent chemical modification of the channel, such as a phosphorylation. Rather, the channels appeared to switch between gating modes. These switches could be spontaneous but were strongly influenced by changes in membrane voltage. Voltage dependence of channel gating was also observed under whole-cell clamp conditions. To see if mechanical perturbations could also influence channel kinetics or gating mode, negative pressures of 10-60 mm Hg were applied to the patch pipette. In most cases (15 out of 22), this maneuver had no significant effect on channel behavior. In 6 out of 22 patches, however, there was a rapid and reversible increase in Po when the pressure was applied. In one patch, there was a reversible decrease. While no consistent effects of pressure could be documented, membrane deformation could contribute to the variation in Po under some conditions.

scholarly journals beta-Adrenergic regulation of protein phosphorylation and its relationship to exocrine secretion in dispersed rat parotid gland acinar cells.

1981 ◽  
Vol 256 (18) ◽  
pp. 9731-9736 ◽  
Author(s):  
B.J. Baum ◽  
J.M. Freiberg ◽  
H. Ito ◽  
G.S. Roth ◽  
C.R. Filburn
Keyword(s):  
Parotid Gland ◽  
Protein Phosphorylation ◽  
Acinar Cells ◽  
Exocrine Secretion ◽  
Beta Adrenergic ◽  
Adrenergic Regulation ◽  
Rat Parotid Gland ◽  
Rat Parotid
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