Dynamics of insulin release by perifused insulin-producing tumoral cells: effects of glucose, forskolin, leucine, barium and theophylline.
Perifused tumoral insulin-producing cells, of the RINm5F line, display a high basal insulin output relative to their hormonal content. D-Glucose (2.8 or 16.7 mmol/l) causes a modest and monophasic increase in insulin output. The secretory response to D-glucose (1.4 to 16.7 mmol/l) is enhanced by forskolin, which exerts little effect in the absence of exogenous nutrient. L-Leucine (10.0 mmol/l) also stimulates insulin release from the perifused cells. The secretory response to these nutrient secretagogues in much less marked, however, than that evoked, in the absence of Ca2+, by the association of Ba2+ and theophylline. It is concluded that the dynamics of insulin release by the tumoral cells, when compared to that of normal islet cells, are characterized by several anomalies, including a high basal ratio between secretion and content, a low threshold (less than or equal to 1.4 mmol/l) in the secretory response to D-glucose, and a lesser responsiveness to nutrient than nonnutrient secretagogues.
Leclercq-Meyer
V
V
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Giroix
M H
MH
Sener
A
A
Marchand
J
J
Malaisse
W J
WJ
D000818:Animals; D001464:Barium / Q000494:pharmacology*; D002461:Cell Line, Transformed; D005576:Colforsin / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects*; D007930:Leucine / Q000494:pharmacology*; D008297:Male; D010190:Pancreatic Neoplasms / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013806:Theophylline / Q000494:pharmacology*
D007328:Insulin; D005576:Colforsin; D001464:Barium; D013806:Theophylline; D007930:Leucine; D005947:Glucose