[Dependence of calcium influx in squid axons on rhythmic excitation frequency]

Calcium-45 influx was measured in squid axons during excitation. Different stimulation frequencies changed this influx and general concentration of calcium ions in squid axons. The maximum influx was recorded at the frequency 10 imp/s and 30 imp/s. Calcium influx and general content of calcium ions in axoplasma during excitation was independent of the number of excitation impulses. The role of sodium and calcium channels during excitation is discussed.