Volume 8 Issue 1, March 1998: 23-31
ORIGINAL ARTICLES
Types of voltage-dependent calcium channels involved in high potassium depolarization-induced amylase secretion in the exocrine pancreatic tumour cell line AR4-2J.
Cui ZJ.
Beijing Agricultural University Faculty of Biological Sciences, China.
Correspondence: Cui ZJ.(bauic@public.bta.net.cn)
In the perifused fura-2 loaded exocrine pancreatic acinar cell line AR4-2J pulses of high potassium induced repetitive increases in intracellular calcium. Attached cells when stimulated with high potassium secreted large amount of amylase. High potassium-induced secretion was dependent both on the concentration of potassium and duration of stimulation. High potassium induced increases in intracellular calcium were inhibited by voltage-dependent calcium channel antagonists with an order of potency as follows: nifedipine > omega-agatoxin IVA > omega-conotoxin GVIA. In contrast, the L-type calcium channel antagonist nifedipine almost completely inhibited potassium-induced amylase secretion, whereas the N-type channel antagonist omega-conotoxin GVIA was without effect. The P-type channel antagonist omega-agatoxin IVA had a small inhibitory effect, but this inhibition was not significant at the level of amylase secretion. In conclusion, the AR4-2J cell line possesses different voltage-dependent calcium channels (L, P, N) with the L-type predominantly involved in depolarization induced amylase secretion.
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