There are 2 studies that match your criteria.
Criteria: Freq Range=300 kHz - 300 GHz (RF/mmW/THz),Study Type=In Vitro,Study Subtype=Signaling (Ca++/Ion Efflux, Neuron Conduction/channels, Muscle Contraction),Status=Completed Without Publication

Details - Project ID 281
Lab	University of Munster, FRG
Study Design	900, 1800 MHz (GSM) exposure to cells and analysis of internal Ca++ levels
Summary	No effects on intracellular Ca++ levels (pre-, during, and post-exposure) in Djungarian hamster pinealocytes (primary culture) and differentiated Y79 human retinoblastoma cells
Citation
Details - Project ID 566
Lab	Beijing Medical University, China
Study Design	450 MHz (CW, AM-16 Hz) exposure to rat synaptosomal membranes and analysis of Ca++ efflux
Summary	Increased Ca++ efflux that was greater with 16 Hz modulated signals
Citation