A concerted action of L- and T-type Ca(2+) channels regulates locus coeruleus pacemaking
Abstract
Dysfunction of noradrenergic locus coeruleus (LC) neurons is involved in psychiatric and neurodegenerative diseases and is an early hallmark of Parkinson's disease (PD). The analysis of ion channels underlying the autonomous electrical activity of LC neurons, which is ultimately coupled to cell survival signaling pathways, can lead to a better understanding of the vulnerability of these neurons. In LC neurons somatodendritic Ca(2+) oscillations, mediated by L-type Ca(2+) channels, accompany spontaneous spiking and are linked to mitochondrial oxidant stress. However, the expression and functional implication of low-threshold activated T-type Ca(2+) channels in LC neurons were not yet studied. To this end we performed RT-PCR expression analysis in LC neurons. In addition, we utilized slice patch clamp recordings of in vitro brainstem slices in combination with L-type and T-type Ca(2+) channel blockers. We found the expression of a distinct set of L-type and T-type Ca(2+) channel subtypes mediating a pronounced low-threshold activated Ca(2+) current component. Analyzing spike trains, we revealed that neither L-type Ca(2+) channel nor T-type Ca(2+) channel blockade alone leads to a change in firing properties. In contrast, a combin...Continue Reading
References
Pharmacological properties of Ca(V)3.2, a low voltage-activated Ca2+ channel cloned from human heart
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