Related Experiment Videos
Diphenylamine-2-carboxylate (DPC) reduces calcium influx in a mouse mandibular cell line (ST885)
P Poronnik1, D I Cook, D G Allen
1Department of Physiology, University of Sydney, New South Wales, Australia.
Abstract:
Non-selective cation channels are found in many diverse cell types and have been proposed as a potential entry path for Ca2+. ST885 cells contain large numbers of these channels which are active in the resting cell. We have used Fura-2 to monitor changes in intracellular free Ca2+ ([Ca2+]i) in response to step changes in extracellular Ca2+ ([Ca2+]o). We found that DPC, a blocker of the non-selective cation channel in these cells, caused a reduction of approximately 50% in the rate of rise in [Ca2+]i following a step increase in [Ca2+]o. Since our experiments demonstrate that this phenomenon is not due to DPC blockade of Cl- channels, the Na+/Ca2+ exchanger or cyclooxygenase, we conclude that it is attributable to a direct effect of DPC on the non-selective cation channel. It thus appears that the non-selective cation channel is a significant pathway for basal Ca2+ entry in these cells.
Insights
Non-selective cation channels facilitate calcium (Ca2+) entry in ST885 cells. Blocking these channels with DPC significantly reduces the rate of intracellular Ca2+ increase, indicating their crucial role in basal Ca2+ influx.
Area of Science:
- Cell Physiology
- Ion Channel Function
Background:
- Non-selective cation channels are present in various cell types and implicated in calcium (Ca2+) entry.
- ST885 cells exhibit numerous active non-selective cation channels at resting potential.
Purpose of the Study:
- To investigate the role of non-selective cation channels in basal Ca2+ entry in ST885 cells.
- To determine the effect of DPC, a non-selective cation channel blocker, on intracellular Ca2+ dynamics.
Main Methods:
- Utilized Fura-2 to measure intracellular free Ca2+ ([Ca2+]i) changes.
- Applied step changes in extracellular Ca2+ ([Ca2+]o) with and without DPC.
- Ruled out DPC effects on Cl- channels, Na+/Ca2+ exchanger, and cyclooxygenase.
Main Results:
- DPC reduced the rate of rise in [Ca2+]i by approximately 50% after an increase in [Ca2+]o.
- This effect was confirmed to be specific to the non-selective cation channel.
- Demonstrated that DPC's action is not mediated by Cl- channels, Na+/Ca2+ exchanger, or cyclooxygenase.
Conclusions:
- Non-selective cation channels represent a significant pathway for basal Ca2+ entry in ST885 cells.
- DPC directly inhibits these channels, impacting Ca2+ homeostasis.
- Findings highlight the functional importance of these channels in cellular Ca2+ regulation.