Measurements of cytoplasmic free Ca2+ concentration in human pancreatic islets and insulinoma cells.
In human pancreatic islets an increase in the glucose concentration from 3 to 20 mM raised the free cytoplasmic Ca2+ concentration [( Ca2+]i), an effect being reversible upon withdrawal of the sugar. Depolarization with a high concentration of K+ or the sulphonylurea tolbutamide also raised [Ca2+]i. Addition of extracellular ATP produced a transient rapid rise in [Ca2+]i. Oscillations in [Ca2+]i were observed in the presence of 10 mM glucose. Insulinoma cells responded to glucose and tolbutamide with increases in [Ca2+]i, whereas the sulphonamide diazoxide caused a decrease in [Ca2+]i. These findings confirm previous results obtained in rodent beta-cells.
Kindmark
H
H
Department of Endocrinology, Karolinska Institute, Stockholm, Sweden.
Köhler
M
M
Nilsson
T
T
Arkhammar
P
P
Wiechel
K L
KL
Rorsman
P
P
Efendić
S
S
Berggren
P O
PO
D000328:Adult; D000368:Aged; D002118:Calcium / Q000737:chemistry*; D003593:Cytoplasm / Q000737:chemistry*; D005260:Female; D016257:Fura-2; D006801:Humans; D007340:Insulinoma / Q000737:chemistry* / Q000473:pathology; D007515:Islets of Langerhans / Q000737:chemistry*; D008297:Male; D014407:Tumor Cells, Cultured
D002118:Calcium; D016257:Fura-2