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Endogenous DHP-sensitive Ca(2+) channels in Pleurodeles oocytes
H Ouadid1, E Browaeys-Poly, J P Vilain
1Laboratoire de Physiologie Cellulaire, Université des Sciences et Technologies, Villeneuve d'Aseq, France.
FEBS Letters
|August 29, 1994
Summary
Pleurodeles oocytes possess high-voltage activated calcium channels. These channels exhibit properties similar to L-type calcium channels, responding to dihydropyridine activators and antagonists.
Area of Science:
- Electrophysiology
- Molecular Biology
- Cell Physiology
Background:
- Voltage-dependent calcium channels are crucial for cellular functions.
- Understanding these channels in amphibian oocytes provides insights into fundamental physiological processes.
Purpose of the Study:
- To characterize the properties of voltage-dependent calcium channels in Pleurodeles oocytes.
- To determine the pharmacological profile of these channels, particularly their sensitivity to dihydropyridines.
Main Methods:
- Utilized the double electrode voltage-clamp technique to record barium currents (IBa).
- Applied various pharmacological agents, including cadmium, omega-conotoxin, Bay K 8644, and nifedipine, to probe channel function.
- Analyzed current activation, inactivation, and voltage-dependence.
Main Results:
- Barium current (IBa) activated at -36.7 mV, peaked at -11.6 mV, and reversed at +55 mV.
- IBa showed slow activation, no inactivation, and was completely inhibited by cadmium (Cd2+).
- The current was insensitive to omega-conotoxin but sensitive to dihydropyridines (DHPs), with Bay K 8644 increasing amplitude and nifedipine decreasing it.
Conclusions:
- Pleurodeles oocytes express high-voltage activated calcium channels.
- These channels share significant electrophysiological and pharmacological similarities with L-type calcium channels found in other species.
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