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3058944 
Journal Article 
Insulin induces cation fluxes and increases intracellular calcium in the HTC rat hepatoma cell line 
Mathe, L; Vallerand, D; Haddad, PS 
2000 
Yes 
Canadian Journal of Gastroenterology
ISSN: 0835-7900 
14 
5 
389-396 
English 
10851278 
WOS:000087558700002 
BACKGROUND/AIMS: Rat hepatoma HTC cells were used to study conductive pathways implicated in insulin induced cation and calcium influx into liver cells. METHODS: Membrane potentials and currents were measured by whole cell parch clamp. Cytosolic calcium was measured using FURA-2 fluorescence. RESULTS: Insulin induced a gradual and reversible depolarization of 5.7+/-0.8 mV. Insulin-induced currents showed a linear slope conductance of 663 pS and a reversal potential of -17.9 mV. Ion substitution experiments showed that these currents were composed mainly of a nonselective cation component. In FURA 2 experiments, insulin caused a slow monophasic rise in HTC cell calcium, which depended on the presence of extracellular calcium. Insulin also induced significant increases of 1.58- and 1.54-fold in basal calcium influx when studied by external calcium withdrawal and readmission, or by the manganese quench method, respectively. Using the latter approach, we found that 100 mu M gadolinium and 10 mu M SKF96365 blocked the rise of the basal manganese quench race induced by insulin whereas 100 mu M verapamil was without effect. CONCLUSIONS: Insulin induces inward cation currents that depolarize HTC cell membrane potentials and participate in increased calcium influx. 
Fura-2; hepatocytes; nonselective cation channels; patch clamping