[The effect of upon the stimulating action of glyburide in the islet cell secretion of insulin and its mechanism].
OBJECTIVE
To study the effect and mechanism of amylin upon oral sulfonylurea drugs and its action to stimulate the islet cell secretion of insulin in rats.


METHODS
Radioimmunogical and fluorescence methods were used to determine the amount of insulin secretion as well as the content of intracellular Ca(2+) of the rat islets incubated with amylin in different concentrations and followed by glyburide stimulation test.


RESULTS
In amylin concentrations of 5 micromol/L and 10 micromol/L, 3 nmol/L glyburide decreased insulin release volume, being (3.8 +/- 1.0) microg/L and (2.1 +/- 1.0) microg/L as compare with (4.9 +/- 0.9) microg/L of the control group (t = 2.313, P < 0.05; t = 5.887, P < 0.01). Intracellular Ca(2+) content in the two concentrations was (270 +/- 15) nmol/L and (130 +/- 15) nmol/L, being markedly decreased as compared with (330 +/- 18) nmol/L of the control group. The changes were dosage related (t = 7.243, P < 0.01; t = 24.143, P < 0.01).


CONCLUSIONS
High concentration of amylin is responsible for the prevention of the rise of Ca(2+) inside in the islet beta-cell acted upon by sulfonylurea drugs, this may be one of the mechanisms that bring about the decreased release of insulin.
Zhu
T
T
Department of Endocrinology, The General Hospital, Tianjin Medical University, Tianjin Institute of Endocrinology, Tianjin 300052.
Yin
W
W
Zhang
W
W
Zhang
W
W
Gao
S
S
Chang
J
J
D000682:Amyloid / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005905:Glyburide / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000682:Amyloid; D007004:Hypoglycemic Agents; D007328:Insulin; D058228:Islet Amyloid Polypeptide; D005905:Glyburide; D002118:Calcium