Extracellular calcium and microwave enhancement of membrane conductance in snail neurons

Arber SL, Lin JC

Radiat Environ Biophys. 1985;24(2):149-56. 1985

Microwave irradiation has been shown to decrease the input resistance of snail neurons. In this study, we examined the role of extracellular calcium in triggering the microwave-induced enhancement of membrane conductance. Two sets of experiments were conducted. In the first set, nerve cells were superfused using Ringer solution with added Cd²⁺ (0.9 mM) which is a known blocker of calcium channels.

In the second set, cells were superfused with low Ca²⁺ (0.7 mM) Ringer solution.

Microwave irradiation was conducted at 2,450 MHz for 30 min with a specific absorption rate of 13 mW/g. It was found that 7 mM to 0.7 mM lowering of Ca²⁺ in bathing solution as well as blocking of calcium channels in neuronal membrane by means of Cd²⁺ did not influence the fall in membrane resistance induced by microwave radiation. In fact, the observed changed in membrane resistance in these experiments were nearly equal to those observed for neurons superfused by normal Ringer's.

Thus, these results rule out the possible contribution of external Ca²⁺ in the observed microwave effect. Experiments with high Ca²⁺ solution also support this conclusion.