Zhu G C, Dudley D T, Saltiel A R
Department of Physiology, University of Michigan Medical School, Ann Arbor 48109.
Biochem Biophys Res Commun. 1991 Jun 14;177(2):771-6. doi: 10.1016/0006-291x(91)91855-7.
The cellular function of amylin is investigated in L6 myocytes, a rat skeletal muscle cell line. Both rat amylin and human amylin-amide acutely cause a dose-dependent increase in cyclic AMP formation in L6 myocytes. 100 nM amylin stimulates intracellular cyclic AMP concentrations 12-fold, whereas human amylin-amide at this concentration causes only a 2-fold increase. Up to 10 mM human amylin has no effect on cyclic AMP levels. Rat calcitonin gene-related peptide (CGRP) is more potent than amylin, causing a 60-fold increase over basal at 1 nM, with an EC50 value of 0.2 nM. The CGRP receptor antagonist, human CGRP8-37 (hCGRP8-37), completely blocks the stimulatory effect of both rat amylin and human amylin-amide on cyclic AMP production. [125I]CGRP binds specifically to a membrane fraction prepared from L6 [125I]CGRP with a Ki of 0.9 nM, while rat amylin also displaces [125I]CGRP with a Ki of 91 nM. Specific binding of [125I]CGRP to plasma membranes of rat liver and brain is also displaced by rat amylin with Ki values of 35 nM and 37 nM, respectively. In contrast, specific binding of [125I]amylin to numerous cells and tissues, under similar conditions, can not be demonstrated. These results suggest that the cellular effects and physiological actions of amylin may be mediated through receptors for CGRP.
在大鼠骨骼肌细胞系L6肌细胞中研究了胰淀素的细胞功能。大鼠胰淀素和人胰淀素酰胺均可急性引起L6肌细胞中环状AMP生成的剂量依赖性增加。100 nM胰淀素可刺激细胞内环状AMP浓度增加12倍，而该浓度下人胰淀素酰胺仅引起2倍的增加。高达10 mM的人胰淀素对环状AMP水平无影响。大鼠降钙素基因相关肽（CGRP）比胰淀素更有效，在1 nM时比基础水平增加60倍，EC50值为0.2 nM。CGRP受体拮抗剂人CGRP8 - 37（hCGRP8 - 37）完全阻断大鼠胰淀素和人胰淀素酰胺对环状AMP产生的刺激作用。[125I]CGRP特异性结合从L6制备的膜组分，[125I]CGRP的Ki为0.9 nM，而大鼠胰淀素也以91 nM的Ki置换[125I]CGRP。大鼠胰淀素也能置换[125I]CGRP与大鼠肝脏和脑膜的特异性结合，其Ki值分别为35 nM和37 nM。相反，在类似条件下，无法证明[125I]胰淀素与许多细胞和组织的特异性结合。这些结果表明，胰淀素的细胞效应和生理作用可能通过CGRP受体介导。
