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...

Peptide toxins have proved to be useful agents, both in discriminating between different components of native calcium channel currents and in the molecular isolation and designation of their cloned channel counterparts. Here, we describe the isolation and characterization of the biochemical and physiological properties of a novel 74-amino acid peptide toxin (DW13.3) extracted from the venom of ...

Voltage-dependent calcium channels are widely distributed in excitable membranes and are involved in the regulation of many cellular functions. These channels can be modulated by neurotransmitters and drugs. There is one particular type of calcium channel in cardiac cells (L-type) whose gating is affected in different ways by beta-adrenoceptor and 1,4-dihydropyridine agonists. We have analysed ...

Two for T Minireview other is more unexpected: a report that the already-known ␣ 1B , ␣ 1C , and ␣ 1E clones can produce single channel activity with many similarities to T-type channels Harvard Medical School Boston, Massachusetts 02115 (Meir and Dolphin, 1998). Perez-Reyes and colleagues identified the new clone by screening GenBank expressed sequence tags (ESTs) for homology to existing ␣ 1 ...

Multiple subtypes of voltage-gated calcium channels are coupled to transmitter release from central neurons; however, only N-type channels have been shown to play a role in autonomic neurons. The aim of the present study was to investigate potential roles for other channel subtypes in transmitter release from parasympathetic neurons in the mouse bladder using calcium channel toxins alone and in...

Tully, Keith and Steven N. Treistman. Distinct intracellular calcium profiles following influx through Nversus L-type calcium channels: role of Ca -induced Ca release. J Neurophysiol 92: 135–143, 2004; 10.1152/jn.01004.2003. Selective activation of neuronal functions by Ca is determined by the kinetic profile of the intracellular calcium ([Ca ]i) signal in addition to its amplitude. Concurrent ...

Verapamil is a prototypical phenylalkylamine (PAA), and it was the first calcium channel blocker to be used clinically. It tonically blocks L-type channels in the inner pore with micromolar affinity, and its affinity increases at depolarized membrane potentials. In T-type calcium channels, verapamil blocks with micromolar affinity and has modestly increased affinity at depolarized potentials. W...

Calcium-induced calcium release (CICR) has been observed in cardiac myocytes as elementary calcium release events (calcium sparks) associated with the opening of L-type Ca 2 1 channels. In heart cells, a tight coupling between the gating of single L-type Ca 2 1 channels and ryanodine receptors (RYRs) underlies calcium release. Here we demonstrate that L-type Ca 2 1 channels activate RYRs to pro...

Both intracellular calcium and transmembrane voltage cause inactivation, or spontaneous closure, of L-type (CaV1.2) calcium channels. Here we show that long-lasting elevations of intracellular calcium to the concentrations that are expected to be near an open channel (>/=100 microM) completely and reversibly blocked calcium current through L-type channels. Although charge movements associated w...