Abstract
Changes in cytosolic intracellular free Ca2+ ([Ca2+](i)) in response to glucose, glyburide, cholinergic agonists, and elevated [K+](o) (external potassium concentration) were measured in cultured human islet β-cells. In the absence of glucose, the mean resting [Ca2+](i) in single β-cells was 84.5 ± 4.7 nM (n = 86) and remained unchanged in low external [Ca2+](o) (Ca2+ concentration) (<0.2 μM) at 23-25 C. Glucose (5.6-33 mM) induced a slow dose-related [Ca2+](i) rise up to 300.0 ± 50.6 nM (n = 19). This [Ca2+](i) rise always occurred with a delay that varied from cell to cell (~10-120 sec), and the steady state [Ca2+](i) exhibited a sigmoidal dependence on glucose concentration (midpoint at 14.9 mM). The glucose- induced rise in [Ca2+](i) was attenuated by about 62% in low external [Ca2+](o) and was not affected by dantrolene, a drug that inhibits Ca2+ release from the endoplasmic reticulum. In the absence or presence of glucose, cholinergic receptor agonists evoked a biphasic increase in [Ca2+](i) up to 350 nM; the delayed component of the [Ca2+](i) rise was blocked by dantrolene. A rapid elevation of [K+](o) to 40 mM also elicited a biphasic rise in [Ca2+](i), which peaked at about 250 nM and was inhibited by the Ca2+ channel antagonist nifedipine. Glyburide (4 μM) in the absence of glucose also induced a [Ca2+](o)-dependent rise in [Ca2+](i). Increasing the concentration of glucose from 4 to 16.7 mM evoked a biphasic pattern of insulin secretion from perifused isolated islets at 37 C. Finally, in the presence of 4 mM glucose, a cholinergic muscarinic receptor agonist stimulated insulin secretion. A glucose-stimulated [Ca2+](i) rise was also studied at 24 and 37 C in cultured rat islet cells. Our results suggest that the Ca2+ required for glucose-induced and muscarinic agonist-potentiated insulin release enters the cytosol from both extracellular and intracellular Ca2+ stores.
| Original language | English |
|---|---|
| Pages (from-to) | 1771-1781 |
| Number of pages | 11 |
| Journal | Endocrinology |
| Volume | 134 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 1994 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
Control of cytosolic free calcium in cultured human pancreatic β-cells occurs by external calcium-dependent and independent mechanisms. / Rojas, Eduardo; Carroll, Patricia B.; Ricordi, Camillo; Boschero, Antonio C.; Stojilkovic, Stanko S.; Atwater, Illani.
In: Endocrinology, Vol. 134, No. 4, 01.04.1994, p. 1771-1781.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Control of cytosolic free calcium in cultured human pancreatic β-cells occurs by external calcium-dependent and independent mechanisms
AU - Rojas, Eduardo
AU - Carroll, Patricia B.
AU - Ricordi, Camillo
AU - Boschero, Antonio C.
AU - Stojilkovic, Stanko S.
AU - Atwater, Illani
PY - 1994/4/1
Y1 - 1994/4/1
N2 - Changes in cytosolic intracellular free Ca2+ ([Ca2+](i)) in response to glucose, glyburide, cholinergic agonists, and elevated [K+](o) (external potassium concentration) were measured in cultured human islet β-cells. In the absence of glucose, the mean resting [Ca2+](i) in single β-cells was 84.5 ± 4.7 nM (n = 86) and remained unchanged in low external [Ca2+](o) (Ca2+ concentration) (<0.2 μM) at 23-25 C. Glucose (5.6-33 mM) induced a slow dose-related [Ca2+](i) rise up to 300.0 ± 50.6 nM (n = 19). This [Ca2+](i) rise always occurred with a delay that varied from cell to cell (~10-120 sec), and the steady state [Ca2+](i) exhibited a sigmoidal dependence on glucose concentration (midpoint at 14.9 mM). The glucose- induced rise in [Ca2+](i) was attenuated by about 62% in low external [Ca2+](o) and was not affected by dantrolene, a drug that inhibits Ca2+ release from the endoplasmic reticulum. In the absence or presence of glucose, cholinergic receptor agonists evoked a biphasic increase in [Ca2+](i) up to 350 nM; the delayed component of the [Ca2+](i) rise was blocked by dantrolene. A rapid elevation of [K+](o) to 40 mM also elicited a biphasic rise in [Ca2+](i), which peaked at about 250 nM and was inhibited by the Ca2+ channel antagonist nifedipine. Glyburide (4 μM) in the absence of glucose also induced a [Ca2+](o)-dependent rise in [Ca2+](i). Increasing the concentration of glucose from 4 to 16.7 mM evoked a biphasic pattern of insulin secretion from perifused isolated islets at 37 C. Finally, in the presence of 4 mM glucose, a cholinergic muscarinic receptor agonist stimulated insulin secretion. A glucose-stimulated [Ca2+](i) rise was also studied at 24 and 37 C in cultured rat islet cells. Our results suggest that the Ca2+ required for glucose-induced and muscarinic agonist-potentiated insulin release enters the cytosol from both extracellular and intracellular Ca2+ stores.
AB - Changes in cytosolic intracellular free Ca2+ ([Ca2+](i)) in response to glucose, glyburide, cholinergic agonists, and elevated [K+](o) (external potassium concentration) were measured in cultured human islet β-cells. In the absence of glucose, the mean resting [Ca2+](i) in single β-cells was 84.5 ± 4.7 nM (n = 86) and remained unchanged in low external [Ca2+](o) (Ca2+ concentration) (<0.2 μM) at 23-25 C. Glucose (5.6-33 mM) induced a slow dose-related [Ca2+](i) rise up to 300.0 ± 50.6 nM (n = 19). This [Ca2+](i) rise always occurred with a delay that varied from cell to cell (~10-120 sec), and the steady state [Ca2+](i) exhibited a sigmoidal dependence on glucose concentration (midpoint at 14.9 mM). The glucose- induced rise in [Ca2+](i) was attenuated by about 62% in low external [Ca2+](o) and was not affected by dantrolene, a drug that inhibits Ca2+ release from the endoplasmic reticulum. In the absence or presence of glucose, cholinergic receptor agonists evoked a biphasic increase in [Ca2+](i) up to 350 nM; the delayed component of the [Ca2+](i) rise was blocked by dantrolene. A rapid elevation of [K+](o) to 40 mM also elicited a biphasic rise in [Ca2+](i), which peaked at about 250 nM and was inhibited by the Ca2+ channel antagonist nifedipine. Glyburide (4 μM) in the absence of glucose also induced a [Ca2+](o)-dependent rise in [Ca2+](i). Increasing the concentration of glucose from 4 to 16.7 mM evoked a biphasic pattern of insulin secretion from perifused isolated islets at 37 C. Finally, in the presence of 4 mM glucose, a cholinergic muscarinic receptor agonist stimulated insulin secretion. A glucose-stimulated [Ca2+](i) rise was also studied at 24 and 37 C in cultured rat islet cells. Our results suggest that the Ca2+ required for glucose-induced and muscarinic agonist-potentiated insulin release enters the cytosol from both extracellular and intracellular Ca2+ stores.
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UR - http://www.scopus.com/inward/citedby.url?scp=0028294981&partnerID=8YFLogxK
U2 - 10.1210/en.134.4.1771
DO - 10.1210/en.134.4.1771
M3 - Article
VL - 134
SP - 1771
EP - 1781
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 4
ER -