T-type alpha 1H Ca2+ channels are involved in Ca2+ signaling during terminal differentiation (fusion) of human myoblasts

Human myoblast fusion requires expression of functional inward rectifier Kir2.1 channels

Myoblast fusion is essential to skeletal muscle development and repair. We have demonstrated previously that human myoblasts hyperpolarize, before fusion, through the sequential expression of two K+ channels: an ether-à-go-go and an inward rectifier. This hyperpolarization is a prerequisite for fusion, as it sets the resting membrane potential in a range at which Ca2+ can enter myoblasts and thereby trigger fusion via a window current through alpha1H T channels.

Odor-evoked calcium signals in dendrites of rat mitral cells

Mitral cell dendrites do more than passively integrate and convey synaptic potentials to the soma, they release transmitter onto local interneurones to mediate recurrent and lateral inhibition. Several mechanisms may control the level of dendritic intracellular calcium ([Ca(2+)]) and define timing for dendritic release. Here we investigated in vivo, how odor controls calcium dynamics in mitral cell dendrites by combining intracellular recording and two-photon microscopy imaging of [Ca(2+)]. During odor stimulation, two types of [Ca(2+)] changes accompany membrane potential oscillations that are phase-locked with the respiratory cycle: (i) one is graded and parallels the membrane potential, even below the threshold for action potential firing; (ii) a second is transient, triggered by sodium action potentials that invade the entire dendritic tree. These results indicate that mitral cell dendritic compartments are synchronized by action potentials and suggest that the efficacy of dendritic synapses is finely tuned by odor-evoked graded changes in [Ca(2+)].

Odor-evoked calcium signals in dendrites of rat mitral cells

Mitral cell dendrites do more than passively integrate and convey synaptic potentials to the soma, they release transmitter onto local interneurones to mediate recurrent and lateral inhibition. Several mechanisms may control the level of dendritic intracellular calcium ([Ca(2+)]) and define timing for dendritic release. Here we investigated in vivo, how odor controls calcium dynamics in mitral cell dendrites by combining intracellular recording and two-photon microscopy imaging of [Ca(2+)]. During odor stimulation, two types of [Ca(2+)] changes accompany membrane potential oscillations that are phase-locked with the respiratory cycle: (i) one is graded and parallels the membrane potential, even below the threshold for action potential firing; (ii) a second is transient, triggered by sodium action potentials that invade the entire dendritic tree. These results indicate that mitral cell dendritic compartments are synchronized by action potentials and suggest that the efficacy of dendritic synapses is finely tuned by odor-evoked graded changes in [Ca(2+)].