Ion channels are responsible for control of cell function in excitable tissues such as heart and brain and also in organs and tissues traditionally thought to be non- excitable including liver and epithelium. In the present research, the effect of lead (Pb2+) on Ca2+ -dependent action potential and currents was studied in F77 neuronal soma membrane of Helix aspersa. For this purpose, action pot...

introduction: the ionic currents show nonlinear behavior and electrical stimuli can influence their activation and inactivation kinetics. the time constant of depolarizing or hyperpolarizing current pulses has an important role in the firing behavior of neurons. in the present study, the effects of quasitrpezoidal command potentials on l-type calcium channel of somata of f1 neuron in helix aspe...

Modulation of the L-type current by sarcoplasmic reticulum (SR) Ca2+ release has been examined in patch-clamped mouse myotubes. Inhibition of SR Ca2+ release by inclusion of ryanodine in the internal solution shifted the half-activating voltage ( V 0.5) of the L-type current from 1.1 ± 2.1 to -7.7 ± 1.7 mV. Ruthenium red in the internal solution shifted V 0.5 from 5.4 ± 1.9 to -3.2 ± 4.1 mV. Ch...

Hippocampal neurons exhibit low-voltage-activated (LVA) and high-voltage-activated (HVA) calcium currents. We characterized the LVA current by recording whole-cell Ca2+ currents from acutely isolated rat hippocampal CA3 pyramidal neurons in 2 mM Ca2+. Long depolarizing steps to -50 mV revealed two components to the LVA current: transient and sustained. The transient phase had a fast decay time ...

The signaling of contraction by Ca2+ in the Syrian hamster (BIO 14.6) heart in the late stage of the cardiomyopathy (220 to 300 days old) was compared with that in age-matched healthy hamster hearts. Membrane current and cell shortening or intracellular Ca2+ transients were measured simultaneously in isolated whole-cell-clamped myocytes. The density of the L-type Ca2+ current was smaller in myo...

T-type Ca2+ current has been recorded in smooth muscle myocytes, and associated interstitial cells, isolated from the gastro-intestinal tract, urinary bladder, urethra, prostate gland, myometrium, vas deferens, lymphatic vessels and airways smooth muscle. By contrast, current through such channels has not been recorded from other tissues, such as the ureter. Whilst the properties of this Ca2+ c...

RATIONALE The development of a refractory period for Ca2+ spark initiation after Ca2+ release in cardiac myocytes should inhibit further Ca2+ release during the action potential plateau. However, Ca2+ release sites that did not initially activate or which have prematurely recovered from refractoriness might release Ca2+ later during the action potential and alter the cell-wide Ca2+ transient. ...

Canine cardiac Purkinje cells contain both Land T-type calcium currents, yet the single Ca2' channels have not been characterized from these cells. Additionally, previous studies have shown an overlap between the steady-state inactivation and activation curves for L-type Ca2' currents, suggesting the presence of L-type Ca2' "window" current. We used the on-cell, patch-clamp technique to study C...