TY - JOUR
T1 - Gramicidin D is a potent insulin secretagogue
T2 - Dependence on extracellular calcium influx
AU - Dibas, Adnan I.
AU - Yorio, Thomas
AU - Easom, Richard A.
PY - 1995
Y1 - 1995
N2 - Gramicidin D, a sodium ionophore, was identified as a potent insulin secretagogue in the mouse β-cell line, βTC3. Gramicidin D stimulated insulin secretion by 3.2-fold relative to control cells incubated with vehicle alone. Using ion-specific fluorescent probes, gramicidin D (1 μM) increased the intracellular concentrations of Na+ ([Na+]i) and Ca2+ ([Ca2+]i). By contrast, no changes in pHi were detected in cells exposed to ionophore. The increase in [Ca2+]i was biphasic and characterized by an initial peak at 1-2 minutes followed by a sustained second phase. The addition of EGTA (2 mM) to the extracellular medium abolished gramicidin D induced increase in [Ca2+]i and insulin secretion. These parameters were also profoundly inhibited by the L-type Ca2+-channel inhibitor, verapamil (20 μM). These findings suggest that insulin secretion induced from βTC3 cells by gramicidin D is mediated via the promotion of Ca2+-influx.
AB - Gramicidin D, a sodium ionophore, was identified as a potent insulin secretagogue in the mouse β-cell line, βTC3. Gramicidin D stimulated insulin secretion by 3.2-fold relative to control cells incubated with vehicle alone. Using ion-specific fluorescent probes, gramicidin D (1 μM) increased the intracellular concentrations of Na+ ([Na+]i) and Ca2+ ([Ca2+]i). By contrast, no changes in pHi were detected in cells exposed to ionophore. The increase in [Ca2+]i was biphasic and characterized by an initial peak at 1-2 minutes followed by a sustained second phase. The addition of EGTA (2 mM) to the extracellular medium abolished gramicidin D induced increase in [Ca2+]i and insulin secretion. These parameters were also profoundly inhibited by the L-type Ca2+-channel inhibitor, verapamil (20 μM). These findings suggest that insulin secretion induced from βTC3 cells by gramicidin D is mediated via the promotion of Ca2+-influx.
UR - http://www.scopus.com/inward/record.url?scp=0029146983&partnerID=8YFLogxK
U2 - 10.1006/bbrc.1995.1990
DO - 10.1006/bbrc.1995.1990
M3 - Article
C2 - 7542876
AN - SCOPUS:0029146983
SN - 0006-291X
VL - 212
SP - 449
EP - 454
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -