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Updated: Apr 7, 2026

Isolation of Intrapulmonary Artery and Smooth Muscle Cells to Investigate Vascular Responses
Published on: June 8, 2022
Orai/CRACM1 and KCa3.1 ion channels interact in the human lung mast cell plasma membrane
S Mark Duffy1, Ian Ashmole1, Dawn T Smallwood1
1Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, UK.
Background:
Orai/CRACM1 ion channels provide the major Ca(2+) influx pathway for FcεRI-dependent human lung mast cell (HLMC) mediator release. The Ca(2+)-activated K(+) channel KCa3.1 modulates Ca(2+) influx and the secretory response through hyperpolarisation of the plasma membrane. We hypothesised that there is a close functional and spatiotemporal interaction between these Ca(2+)- and K(+)-selective channels.
Results:
Activation of FcεRI-dependent HLMC KCa3.1 currents was dependent on the presence of extracellular Ca(2+), and attenuated in the presence of the selective Orai blocker GSK-7975A. Currents elicited by the KCa3.1 opener 1-EBIO were also attenuated by GSK-7975A. The Orai1 E106Q dominant-negative mutant ablated 1-EBIO and FcεRI-dependent KCa3.1 currents in HLMCs. Orai1 but not Orai2 was shown to co-immunoprecipitate with KCa3.1 when overexpressed in HEK293 cells, and Orai1 and KCa3.1 were seen to co-localise in the HEK293 plasma membrane using confocal microscopy.
Conclusion:
KCa3.1 activation in HLMCs is highly dependent on Ca(2+) influx through Orai1 channels, mediated via a close spatiotemporal interaction between the two channels.
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