scholarly journals Role of phosphodiesterases in the shaping of sub-plasma-membrane cAMP oscillations and pulsatile insulin secretion

2012 ◽  
Vol 125 (21) ◽  
pp. 5084-5095 ◽  
Author(s):  
G. Tian ◽  
J. Sagetorp ◽  
Y. Xu ◽  
H. Shuai ◽  
E. Degerman ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
Pulsatile Insulin Secretion

scholarly journals Lipid transport by TMEM24 at ER–plasma membrane contacts regulates pulsatile insulin secretion

Science ◽  
2017 ◽  
Vol 355 (6326) ◽  
pp. eaah6171 ◽  
Author(s):  
Joshua A. Lees ◽  
Mirko Messa ◽  
Elizabeth Wen Sun ◽  
Heather Wheeler ◽  
Federico Torta ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
Lipid Transport ◽  
Membrane Contacts ◽  
Pulsatile Insulin Secretion

scholarly journals Dominant Role of Sarcoendoplasmic Reticulum Ca2+-ATPase Pump in Ca2+ Homeostasis and Exocytosis in Rat Pancreatic β-Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (3) ◽  
pp. 1396-1407 ◽  
Author(s):  
Elizabeth Hughes ◽  
Andy K. Lee ◽  
Amy Tse
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
Membrane Potential ◽  
Simultaneous Measurement ◽  
Dominant Role ◽  
Capacitance Measurement ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Serca Pump

The exocytosis of insulin-containing granules from pancreatic β-cells is tightly regulated by changes in cytosolic Ca2+ concentration ([Ca2+]i). We investigated the role of the sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) pump, Na+/Ca2+ exchanger, and plasma membrane Ca2+-ATPase pump in the Ca2+ dynamics of single rat pancreatic β-cells. When the membrane potential was voltage clamped at −70 mV (in 3 mm glucose at ∼22 or 35 C), SERCA pump inhibition dramatically slowed (∼4-fold) cytosolic Ca2+ clearance and caused a sustained rise in basal [Ca2+]i via the activation of capacitative Ca2+ entry. SERCA pump inhibition increased (∼1.8-fold) the amplitude of the depolarization-triggered Ca2+ transient at approximately 22 C. Inhibition of the Na+/Ca2+ exchanger or plasma membrane Ca2+-ATPase pump had only minor effects on Ca2+ dynamics. Simultaneous measurement of [Ca2+]i and exocytosis (with capacitance measurement) revealed that SERCA pump inhibition increased the magnitude of depolarization-triggered exocytosis. This enhancement in exocytosis was not due to the slowing of the cytosolic Ca2+ clearance but was closely correlated to the increase in the peak of the depolarization-triggered Ca2+ transient. When compared at similar [Ca2+]i with controls, the rise in basal [Ca2+]i during SERCA pump inhibition did not cause any enhancement in the magnitude of the ensuing depolarization-triggered exocytosis. Therefore, we conclude that in rat pancreatic β-cells, the rapid uptake of Ca2+ by SERCA pump limits the peak amplitude of depolarization-triggered [Ca2+]i rise and thus controls the amount of insulin secretion.

Plasma membrane depolarization as a determinant of the first phase of insulin secretion

2009 ◽  
Vol 297 (2) ◽  
pp. E315-E322 ◽  
Author(s):  
K. Hatlapatka ◽  
M. Willenborg ◽  
I. Rustenbeck
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
Action Potential ◽  
Membrane Depolarization ◽  
Secretory Response ◽  
Nmri Mouse ◽  
Β Cells ◽  
Mouse Islets ◽  
Kinetics Of

The role of plasma membrane depolarization as a determinant of the initial phase of insulin secretion was investigated. NMRI mouse islets and β-cells were used to measure the kinetics of insulin secretion, ATP and ADP content, membrane potential, and cytosolic free Ca2+ concentration ([Ca2+]i). The depolarization of metabolically intact β-cells by KCl corresponded closely to the theoretical values. In contrast to physiological (glucose) or pharmacological (tolbutamide) ATP-sensitive K+ (KATP) channel block, KCl depolarization did not induce action potential spiking. The depolarization by 15 mM K+ (21 mV) corresponded to the plateau depolarization by 50 or 500 μM tolbutamide; that by 40 mM K+ (41 mV) corresponded to the action potential peaks. Nifedipine and diazoxide abolished action potentials but not KCl depolarization, suggesting that the depolarizing strength of 15, but not 40 mM K+ corresponds to that of KATP channel closure. K+ (40 mM) induced a massive secretory response in the presence of 5 mM glucose, whereas 15 mM K+, like 50 μM tolbutamide, was only slightly effective, even though a marked increase in [Ca2+]i was produced. Raising glucose from 5 to 10 mM in the continued presence of 15 mM K+ resulted in a strongly enhanced biphasic response. The depolarization pattern of this combination could be mimicked by combining basal glucose with 15 mM K+ and 50 μM tolbutamide; however, the secretory response to these nonnutrients was much weaker. In conclusion, the initial secretory response to nutrient secretagogues is largely influenced by signaling mechanisms that do not involve depolarization.

Pulsatile insulin secretion from isolated human pancreatic islets

Diabetes ◽  
1994 ◽  
Vol 43 (6) ◽  
pp. 827-830 ◽  
Author(s):  
P. Marchetti ◽  
D. W. Scharp ◽  
M. Mclear ◽  
R. Gingerich ◽  
E. Finke ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Human Pancreatic Islets ◽  
Pulsatile Insulin Secretion
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