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Calcium-dependent action potentials in leech giant salivary cells
The Journal of Experimental Biology
|November 1, 1984
Summary
Giant salivary cells in leeches generate action potentials dependent on calcium currents. These findings in Haementeria leeches reveal a unique physiological mechanism for impulse generation in sanguivorous invertebrates.
Area of Science:
- Zoology
- Physiology
- Neurobiology
Background:
- Haementeria ghilianii and Haementeria officinalis leeches possess paired salivary glands at the proboscis base.
- These glands contain over 200 giant salivary cells with individual ductules, lacking acinar structure or common ducts.
Purpose of the Study:
- To investigate the electrophysiological properties of salivary cells in Haementeria leeches.
- To determine the ionic basis of action potential generation in these cells.
Main Methods:
- Electrophysiological recordings of salivary cells using depolarizing and hyperpolarizing pulses.
- Assessment of action potential generation in solutions with altered ionic composition (sodium-free, calcium replaced with strontium or barium).
Main Results:
- Salivary cells exhibit action potentials (100-200 ms duration, 70-100 mV amplitude).
- Impulses are abolished by calcium current antagonists.
- Action potentials persist in sodium-free solutions and when calcium is replaced by strontium or barium.
Conclusions:
- The action potential in Haementeria salivary cells is primarily dependent on calcium currents.
- This suggests a unique calcium-based impulse mechanism in these sanguivorous leeches.