title: Autorhythmicity and entrainment in excitable membranes.
abstract: Low calcium increases the excitability of neurones and can induce autorhythmicity in excitable cells. Numerical solutions of the Hodgkin-Huxley membrane equations, and numerical evaluations of the small-signal impedance and admittance are used to illustrate the increase in resonance produced by low [Ca2+]0. The resonant frequency may be located either by the peak of the amplitude of the impedance, or by the frequency at which the phase angle is zero for 1 : 1 entrained action potentials. Autorhythmicity is produced by any mechanism which increases the resonant peak of the amplitude of the membrane impedance.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D049832:Decapodiformes; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D008566:Membranes / Q000187:drug effects / Q000502:physiology*; D008954:Models, Biological; D009474:Neurons / Q000502:physiology*; D010507:Periodicity
chemical_list: D002118:Calcium