Properties of slow early potassium current in neurons of snail Helix pomatia |
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| Affiliation: | 1. Department of Dentistry, Guangzhou Health Science College, Guangzhou, PR China;2. School of Dentistry, Hainan Medical University, Haikou, PR China;3. Department of Health Management Center, The First Affiliated Hospital of Hainan Medical University, Haikou, PR China;4. Department of Dentistry, The Second Affiliated Hospital of Hainan Medical University, Haikou, PR China;5. School of International Education, Hainan Medical University, Haikou, PR China;6. Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, PR China;7. Guangdong provincial key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, PR China;1. Department of Anesthesiology, the First Affiliated Hospital of Xiamen University, Fujian 361000, China;2. Department of Thoracic Surgery, the First Affiliated Hospital of Xiamen University, Fujian 361000, China;3. The School of Clinical Medicine, Fujian Medical University, Fujian 361000, China |
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| Abstract: | - 1.1. In isolated neurons of visceral ganglia of snail Helix pomatia a slow early outward current (IAs) was studied using a two-microelectrode voltage clamp technique.
- 2.2. The time of activation and inactivation of IAs at −40 mV were 90–120 msec and 3–5 sec respectively. The removal of inactivation at −120 mV took 2–5 min.
- 3.3. The reversal potential of the IAs was about −80mV in normal saline and was sensitive to the external potassium concentration, changing about 35 mV per fivefold change in potassium over the range from 4 to 20 mM. The results suggest that IAs were due to K+.
- 4.4. The IAs persisted in Ca2+-free medium and in the presence of Ca2+-channels blockers, e.g., Cd2+.
- 5.5. The IAs were blocked by 1–10 μM extracellular 4-aminopyridine, 1 mM of tetraethylammonium ions, 1 mM of Ba2+, but one was resistant to 1 mM Cs+.
- 6.6. 4-aminopyridine had a dual effect on the IAs. It blocked the normal current, and then appeared to increase the inactivated currents.
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