Tight regulation of calcium entry through the L-type calcium channel CaV1.2 ensures optimal excitation-response coupling. In this issue of Neuron, Michailidis et al. (2014) demonstrate that CaV1.2 activity triggers negative feedback regulation through proteolytic cleavage of the channel within the core of the pore-forming subunit.

Neuronal L-type calcium channels are essential for regulating activity-dependent gene expression, but they are thought to open too slowly to contribute to action potential-dependent calcium entry. A complication of studying native L-type channels is that they represent a minor fraction of the whole-cell calcium current in most neurons. Dihydropyridine antagonists are therefore widely used to es...

Neuronal L-type calcium channels contribute to dendritic excitability and activity-dependent changes in gene expression that influence synaptic strength. Phosphorylation-mediated enhancement of L-type channels containing the CaV1.2 pore-forming subunit is promoted by A-kinase anchoring proteins (AKAPs) that target cAMP-dependent protein kinase (PKA) to the channel. Although PKA increases L-type...

Whole cell currents and miniature glutamatergic synaptic events (minis) were recorded in vitro from cardiac vagal neurons in the nucleus ambiguus using the patch-clamp technique. We examined whether voltage-dependent calcium channels were involved in the nicotinic excitation of cardiac vagal neurons. Nicotine evoked an inward current, increase in mini amplitude, and increase in mini frequency i...

We have studied the effect of 8-bromo-cyclic GMP (8-Br-cGMP) on cloned cardiac L-type calcium channel currents to determine the site and mechanism of action underlying the functional effect. Rabbit cardiac alpha(1C) subunit, in the presence or absence of beta(1) subunit (rabbit skeletal muscle) or beta(2) subunit (rat cardiac/brain), was expressed in Xenopus oocytes, and two-electrode voltage-c...

Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated CaV2.1 (P/Q-type) and CaV3.2 (α1H T-type) calcium channels; KLHL1 knockdown experiments (KD) cause down-regulation of both channel types and altered synaptic properties in cultured rat hippocampal neurons (Perissinotti et al., 2014). Here, we studied the effect of ablation of KLHL1 on calcium channel function ...

It is universally believed that the removal of external sodium ions is without effect on calcium current. We now report that in enzymatically isolated guinea pig ventricular cells, the replacement of external sodium ions with certain other cations causes a 3- to 6-fold increase in peak L-type calcium current. The increase in current is reversibly blocked by L-type calcium-channel antagonists, n...

Calcium entry into the dendritic spines of excitatory neurons is important for many forms of synaptic plasticity. In this issue, Hoogland and Saggau continue efforts to inventory the calcium channels that function in dendritic spines. They evoked backpropagating action potentials at the soma of CA1 neurons in rat hippocampal slices and recorded calcium transients in basal dendrites and spines u...

The aim of this study was to explore the effect and action mechanisms of intermittent hypoxia on the production of testosterone both in vivo and in vitro. Male rats were housed in a hypoxic chamber (12% O(2) + 88% N(2), 1.5 l/ml) 8 h/day for 4 days. Normoxic rats were used as control. In an in vivo experiment, hypoxic and normoxic rats were euthanized and the blood samples collected. In the in ...