Properties of voltage-gated Ca2+ currents measured from mouse pancreatic â-cells in situ
Biol. Res
;
39(3): 505-520, 2006. ilus
Article
in English
| LILACS
| ID: lil-437383
ABSTRACT
We used the single-microelectrode voltage-clamp technique to record ionic currents from pancreatic â-cells within intact mouse islets of Langerhans at 37C, the typical preparation for studies of glucose-induced "bursting" electrical activity. Cells were impaled with intracellular microelectrodes, and voltage pulses were applied in the presence of tetraethylammonium. Under these conditions, a voltage-dependent Ca2+ current (I Cav), containing L-type and non-L-type components, was observed. The current measured in situ was larger than that measured in single cells with whole-cell patch clamping, particularly at membrane potentials corresponding to the action potentials of â-cell electrical activity. The temperature dependence of I Cav was not sufficient to account for the difference in size of the currents recorded with the two methods. During prolonged pulses, the voltage-dependent Ca2+ current measured in situ displayed both rapid and slow components of inactivation. The rapid component was Ca2+-dependent and was inhibited by the membrane-permeable Ca2+ chelator, BAPTA-AM. The effect of BAPTA-AM on â-cell electrical activity then demonstrated that Ca2+-dependent inactivation of I Cav contributes to action potential repolarization and to control of burst frequency. Our results demonstrate the utility of voltage clamping â-cells in situ for determining the roles of ion channels in electrical activity and insulin secretion.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Calcium Channels
/
Insulin-Secreting Cells
/
Membrane Potentials
Limits:
Animals
Language:
English
Journal:
Biol. Res
Journal subject:
Biology
Year:
2006
Type:
Article
/
Project document
Affiliation country:
Chile
Institution/Affiliation country:
Universidad de Chile/CL
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