Different secretory response of pancreatic islets and insulin secreting cell lines INS-1 and INS-1E to osmotic stimuli.
Objective of this study was to characterize osmotically-induced insulin secretion in two tumor cell lines. We compared response of freshly isolated rat pancreatic islets and INS-1 and INS-1E tumor cell lines to high glucose, 30 % hypotonic medium and 20 % hypertonic medium. In Ca(2+)-containing medium glucose induced insulin release in all three cell types. Hypotonicity induced insulin secretion from islets and INS-1 cells but not from INS-1E cells, in which secretion was inhibited despite similar increase in cell volume in both cell types. GdCl(3) (100 micromol/l) did not affect insulin response from INS-1E cells to hypotonic challenge. Hypertonic medium inhibited glucose-induced insulin secretion from islets but not from tumor cells. Noradrenaline (1 micromol/l) inhibited glucose-induced but not swelling-induced insulin secretion from INS-1 cells. Surprisingly, perifusion with Ca(2+)-depleted medium showed distinct secretory response of INS-1E cells to hypotonicity while that of INS-1 cells was partially inhibited. Functioning glucose-induced insulin secretion is not sufficient prerequisite for hypotonicity-induced response in INS-1E cells suggesting that swelling-induced exocytosis is not essential step in the mechanism mediating glucose-induced insulin secretion. Both cell lines are resistant to inhibitory effect of hyperosmolarity on glucose-induced insulin secretion. Response of INS-1E cells to hypotonicity is inhibited by the presence of Ca(2+) in medium.
Institute of Experimental Endocrinology, Center of Excellence of the Slovak Academy of Sciences, Bratislava, Slovakia.
M
M
Orečná
R
R
Hafko
Z
Z
Bačová
J
J
Podskočová
D
D
Chorvát
V
V
Štrbák
D000818:Animals; D002118:Calcium / Q000172:deficiency / Q000378:metabolism; D045744:Cell Line, Tumor; D048429:Cell Size; D005089:Exocytosis; D005682:Gadolinium / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D009997:Osmotic Pressure; D010190:Pancreatic Neoplasms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D007328:Insulin; D005682:Gadolinium; D005947:Glucose; C038958:gadolinium chloride; D002118:Calcium; D009638:Norepinephrine