Calcium-dependent chloride channels in plasma membrane of oocytes from toad, Bufo bufo gargarizans.
- Author:
Yan-Li PI
1
;
Ji-Hua MA
;
Pei-Hua ZHANG
;
Jing-Jing DUAN
Author Information
1. Cardio-Electrophysiological Research Laboratory, Medical College, Wuhan University of Science and Technology, Wuhan 430080, China.
- Publication Type:Journal Article
- MeSH:
4-Aminopyridine;
toxicity;
Animals;
Bufo bufo;
Calcium;
metabolism;
Cell Membrane;
metabolism;
Chloride Channels;
drug effects;
physiology;
Female;
Nitrobenzoates;
pharmacology;
Oocytes;
metabolism;
Tetraethylammonium Compounds;
pharmacology;
Verapamil;
pharmacology
- From:
Acta Physiologica Sinica
2006;58(5):471-476
- CountryChina
- Language:Chinese
-
Abstract:
In this paper, membrane current properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using two-microelectrode voltage clamp technique. Axion of adult female toad was destroyed, and then ovarian lobes containing oocytes in stage I to VI were removed and incubated in Ca(2+)-free ND96 solution with collagenase (1.5 mg/ml) for 1 h. Subsequently, the oocytes were washed in Ca(2+)-free ND96 solution for 10 min to completely remove the follicular layer. For the experiments only the oocytes in stage V and VI were selected and used during 1 to 5 d. The membrane was depolarized from a holding potential of -80 mV to +60 mV in 10 mV step. It was found that a sustained outward current was elicited by depolarization. Potassium channel blockers (tetraethylammonium chloride, TEA, 10 mmol/L and 4-aminopyridine, 4-AP, 10 mmol/L) reduced the outward current to (23.4+/-0.72)% of the maximum. However, further addition of chloride channel blocker (5-nitro-2, 3-phenypropylamino benzoate, NPPB, 30 micromol/L) could almost completely block the outward current to (2.1+/-0.08)% of the maximum. In the presence of TEA and 4-AP, removal of extracellular Ca(2+) or adding verapamil (40 micromol/L), could also reduce the outward current to (2.2+/-0.04) % and (3.1+/-0.15) % of the maximum, respectively. It is concluded that calcium-dependent chloride channels exist in plasma membrane of Bufo bufo gargarizans oocytes, besides potassium channels.
