Journal: The Journal of Physiology
Article Title: Subthreshold oscillation of the membrane potential in magnocellular neurones of the rat supraoptic nucleus
Figure Lengend Snippet: Subthreshold oscillation of the membrane potential and EPSPs in magnocellular neurones A , voltage dependence of the initiation of subthreshold oscillation of the membrane potential in a magnocellular neurone. Shallow oscillation waves are generated at -48 mV, a membrane potential 5 mV positive to resting membrane potential of -53 mV. Close to the threshold for the initiation of action potentials, prominent oscillation waves with varying amplitude are generated. B , in another neurone with identical resting membrane potential spontaneously occurring EPSPs are recorded at rest. The decay phase of EPSPs is markedly slower compared to that of oscillation waves. C , application of 2 mM 1-heptanol did not block the generation of membrane potential oscillation. D , close to the threshold for initiation of action potentials large amplitude oscillation waves are generated. E , relaxation from long-lasting hyperpolarization is followed by a rebound depolarization, resulting in the generation of subthreshold oscillation with waxing amplitude finally inducing a short burst of action potentials. The lower trace in E represents current recording. The initial hyperpolarized part of the voltage trace is out of range. Records are truncated in C-E.
Article Snippet: Mechanisms involved in the generation of rhythmic membrane potential fluctuations were pharmacologically characterized by addition of specific agents to the bath: 4-aminopyridine (4-AP, 0.5-5 mM; Sigma), apamin (50-500 nM; Alomone, Israel), bicuculline methochloride (1-50 μM; Sigma), carbamylcholine chloride (carbachol, 50-100 μM; Sigma), charybdotoxin (ChTX, 5-15 nM; Alomone), 1-heptanol (2-3 mM; Merck, Germany), iberiotoxin (IbTX, 50-200 nM; Alomone), kynurenic acid (2-3 mM; Sigma), procaine (100 μM; Sigma), TEA (1-15 mM; Sigma), TTX (1.25-2.5 μM; Sigma), BaCl2 (1-2 mM; Sigma), CdCl2 (0.3-1 mM; Merck) and CsCl (2-6 mM; Sigma).
Techniques: Generated, Blocking Assay