Nifedipine is an antagonist to cyclotron resonance enhancement of 45Ca incorporation in human lymphocytes

The incorporation of 45Ca in mixed human lymphocytes was measured following one-hour exposures of the cells to combined steady and periodic magnetic fields designed to probe for cyclotron resonance response in calcium incorporation. Measurements were made as a function of magnetic field frequency, up to 30 Hz, and as a function of magnetic field amplitude, up to 1.5 × 10 −4 T rms. The amplitude measurements demonstrated that the relative 45Ca uptake at resonance follows different mechanisms of interaction above and below 0.2 × 10 −4 T rms. After adjusting the magnetic field configuration for maximum incorporation, we then determined the effects of the calcium influx blocker nifedipine on 45Ca incorporation, with and without simultaneous exposure to this specific magnetic field combination. The presence of nifedipine in both unexposed and exposed cell suspensions resulted in decreased 45Ca uptake, presumably through the slow inward calcium channels. Evidence was found suggesting that nifedipine acts antagonistially to the 45Ca cyclotron resonance tuning signal.