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Mn2+ ions pass through Ca2+ channels in myoepithelial cells
1Department of Biological Sciences, Smith College, Northampton, Massachusetts 01063, USA.
The Journal of Experimental Biology
|October 1, 1979
Summary
Marine worm myoepithelial cells generate calcium spikes, with manganese ions also traversing these calcium channels. While manganese can trigger spikes, it doesn't initiate contraction like calcium.
Area of Science:
- Marine Biology
- Cell Physiology
- Neurophysiology
Background:
- Myoepithelial cells in the marine annelid Syllis spongiphila's proventriculus exhibit electrical excitability.
- Understanding the ionic mechanisms underlying these cellular responses is crucial for comprehending their physiological function.
Purpose of the Study:
- To investigate the ionic basis of regenerative electrical responses in Syllis spongiphila myoepithelial cells.
- To determine the role of calcium ions and other divalent cations in generating these cellular events.
Main Methods:
- Intracellular recordings were performed on myoepithelial cells of Syllis spongiphila.
- Electrical stimulation and pharmacological manipulations using various ion concentrations (Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, La3+, Zn2+) in artificial sea water (ASW) were employed.
Main Results:
- Regenerative responses (Ca-spikes) were observed in myoepithelial cells, associated with cell contraction.
- These responses were dependent on extracellular calcium and could be mimicked by barium and strontium ions.
- Manganese ions elicited regenerative responses but did not induce contraction, suggesting a partial but incomplete functional substitution for calcium.
Conclusions:
- Myoepithelial cells of Syllis spongiphila generate action potentials dependent on calcium influx (Ca-spikes).
- Manganese, strontium, and barium ions can permeate calcium channels, with manganese partially substituting for calcium in electrical signaling but not in initiating contraction.