[Bioelectric characteristics of A and B neurons in the mollusc Coretus corneus with different calcium and sodium contents in the medium].
Action potentials (AP) of neurons A and B could be only elicited in the presence of Na-+ ions. An increase in [Ca-++]0 led to depolarization of neurons, enhancement of their excitability, AP, overshoot, of positive afterpotential, AP duration, AP maximal rate of fall (Vf) and to decrease in AP maximal rate of rise (Vr). After addition of CaCl2 up to 50 mmoles into the Ringer solution, the membrane resistance (R) increased. If the [Na-+]0 was equimolarly diminished, R increased up to the [Ca-++]0 30 mmoles, but at greater [Ca-++]0 R fall below the initial value. The regularities were independent of the initial value of resting potential (RP). At high [Ca-++]0 Ca-++ contributed to the generation of the inward current during AP while Na-+ caused an increase in ionic (calcium) membrane permeability at rest. At high [Ca-++]0, Na-+ was also necessary for support of membrane channels which maintained the inward and outward currents during the AP.
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D066298:In Vitro Techniques; D008974:Mollusca / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology*
D012964:Sodium; D002118:Calcium
Bioélektricheskie kharakteristiki neĭronov A i B molliuska Coretus corneus pri razlichnom soderzhanii kal'tsiia i natriia v srede