[The effects of amylin on the islet beta-cells voltage-gated L-calcium channels in rats].
OBJECTIVE
To observe the effect of amylin on the islet beta-cells voltage-gated L-calcium channels in rats.


METHODS
Patch clamp technique was employed in the observation of the features and changes of electric current of islet beta-cells voltage-gated L-calcium channels before and after using amylin.


RESULTS
In the glucose environment of 5.5 mmol/L, the electric current of rat islet beta-cells voltage-gated L-calcium channels was activated at -40 mV and reached the peak at about +20 mV, with a peak value of about -120 pA and the insulin secretion level was (0.76 +/- 0.12) microg/L. Under the stimulation of glucose of 16.7 mmol/L, the peak current voltage moved to the left and increased up to - 140 pA and the level of insulin secretion measured (1.78 +/- 0.13) microg/L. Hatch islet beta-cells in amylin at the concentrations of 0.5, 1.0, 5.0 and 10.0 micromol/L, respectively. It was observed that in the 0.5 micromol/L and 1.0 micromol/L groups, there was no remarkable change in the peak potential activation voltage, current, and insulin secretion volume in comparison with the control group. However, in the environment of 5.5 mmol/L glucose, the increase of activation voltage of the 5.0 and 10.0 micromol/L groups was - 30 mV, with the peak current reduced to approximately -80 pA and -60 pA and the insulin secretion decreased to (0.49 +/- 0.11) microg/L and (0.36 +/- 0.12) microg/L respectively. Under the concentration of 16.7 mmol/L glucose, the activation voltage increased from -40 mV up to -30 mV and the peak current reduced to -80 pA and -40 pA. In the meantime, the insulin secretion decreased respectively to (1.20 +/- 0.13) microg/L and (0.89 +/- 0.14) microg/L, which is of significance.


CONCLUSIONS
The secretion of insulin is synchronized with the opening of the islet beta-cells voltage-gated L-calcium channels at the stimulation of glucose. The amylin inhibition of the insulin secretion is also synchronized with the opening of islet beta-cells voltage-gated L-calcium channels and it's in a positive concentration-dependent manner.
Zhu
Tie-Hong
TH
Department of Endocrinology, The General Hospital, Tianjin Medical University, Tianjin, China. zhutiehong@163.com
Wang
Yin-Xia
YX
He
Bing-Jun
BJ
Zang
Jing-Jing
JJ
Liu
Dong-Bo
DB
Ding
Xue-Mei
XM
D000682:Amyloid / Q000494:pharmacology*; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002478:Cells, Cultured; D007328:Insulin / Q000378:metabolism; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar
D000682:Amyloid; D020746:Calcium Channels, L-Type; D007328:Insulin; D058228:Islet Amyloid Polypeptide