Tungstate stimulates insulin release and inhibits somatostatin output in the perfused rat pancreas.
In the rat pancreas, infusion of sodium-tungstate stimulates basal insulin release in a dose-dependent manner. We have studied tungstate's effects on the insulin secretion elicited by various B-cell secretagogues. Somatostatin output was also measured. The study was performed in the perfused pancreas isolated from normal or somatostatin-depleted pancreases as induced by cysteamine pre-treatment. In control rats, tungstate co-infusion (5 mM) potentiated the insulin secretory responses to glucose (2.7-fold; P<0.01), arginine (2-fold; P<0.01), exendin-4 (3-fold; P<0.01), glucagon (4-fold; P<0.05), and tolbutamide (2-fold; P<0.01). It also inhibited the somatostatin secretory responses to glucose (90%; P<0.01), arginine (95%; P<0.01), glucagon (80%; P<0.025), exendin-4 (80%; P<0.05) and tolbutamide (85%; P<0.01). In somatostatin-depleted pancreases, the stimulatory effect of tungstate on basal insulin secretion and its potentiation of arginine-induced insulin output were comparable to those found in control rats. Our observations suggest an amplifying effect of tungstate on a common step in the insulin stimulus/secretion coupling process, and would rule out a paracrine effect mediated by the inhibition of somatostatin secretion induced by this compound.
Silvestre
Ramona A
RA
Hospital Universitario Puerta de Hierro and Department of Physiology, Universidad Autónoma de Madrid, San Martín de Porres 4, 28035 Madrid, Spain. rsilvestre.hpth@salud.madrid.org
Egido
Eva M
EM
Hernández
Raquel
R
Marco
José
J
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D003543:Cysteamine / Q000494:pharmacology; D000077270:Exenatide; D005947:Glucose / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D013004:Somatostatin / Q000378:metabolism*; D014044:Tolbutamide / Q000494:pharmacology; D017973:Tungsten Compounds / Q000494:pharmacology*; D014688:Venoms / Q000494:pharmacology
D007004:Hypoglycemic Agents; D007328:Insulin; D010455:Peptides; D017973:Tungsten Compounds; D014688:Venoms; D013004:Somatostatin; D003543:Cysteamine; D001120:Arginine; D014044:Tolbutamide; D000077270:Exenatide; D005947:Glucose; C045951:tungstate