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Low voltage-activated (T-type) calcium currents are observed in many central and peripheral neurons and display distinct physiological and functional properties. Using in situ hybridization, we have localized central and peripheral nervous system expression of three transcripts (alpha1G, alpha1H, and alpha1I) of the T-type calcium channel family (CaVT).(More)
Nickel has been proposed to be a selective blocker of low-voltage-activated, T-type calcium channels. However, studies on cloned high-voltage-activated Ca(2+) channels indicated that some subtypes, such as alpha1E, are also blocked by low micromolar concentrations of NiCl(2). There are considerable differences in the sensitivity to Ni(2+) among native(More)
Low voltage-activated Ca2+ channels play important roles in pacing neuronal firing and producing network oscillations, such as those that occur during sleep and epilepsy. Here we describe the cloning and expression of the third member of the T-type family, alpha1I or CavT.3, from rat brain. Northern analysis indicated that it is predominantly expressed in(More)
The molecular diversity of voltage-activated calcium channels was established by studies showing that channels could be distinguished by their voltage-dependence, deactivation and single-channel conductance. Low-voltage-activated channels are called 'T' type because their currents are both transient (owing to fast inactivation) and tiny (owing to small(More)
Voltage-activated Ca2+ channels exist as multigene families that share common structural features. Different Ca2+ channels are distinguished by their electrophysiology and pharmacology and can be classified as either low or high voltage-activated channels. Six alpha1 subunit genes cloned previously code for high voltage-activated Ca2+ channels; therefore,(More)
The cardiac sodium channel alpha subunit (RHI) is less sensitive to tetrodotoxin (TTX) and saxitoxin (STX) and more sensitive to cadmium than brain and skeletal muscle (microliter) isoforms. An RHI mutant, with Tyr substituted for Cys at position 374 (as in microliter) confers three properties of TTX-sensitive channels: (i) greater sensitivity to TTX(More)
Calcium ion (Ca2+) influx through voltage-gated Ca2+ channels is important for the regulation of vascular tone. Activation of L-type Ca2+ channels initiates muscle contraction; however, the role of T-type Ca2+ channels (T-channels) is not clear. We show that mice deficient in the alpha1H T-type Ca2+ channel (alpha(1)3.2-null) have constitutively constricted(More)
The biophysical properties of T-type voltage-gated calcium channels are well suited to pacemaking and to supporting calcium flux near the resting membrane potential in both excitable and non-excitable cells. We have identified a new scorpion toxin (kurtoxin) that binds to the alpha 1G T-type calcium channel with high affinity and inhibits the channel by(More)
Arachidonic acid (AA) and the products of its metabolism are central mediators of changes in cellular excitability. We show that the recently cloned and expressed T-type or low-voltage-activated Ca channel, alpha1H, is modulated by external AA. AA (10 microM) causes a slow, time-dependent attenuation of alpha1H current. At a holding potential of -80 mV, 10(More)
Voltage-gated Na+ channels in mammalian heart differ from those in nerve and skeletal muscle. One major difference is that tetrodotoxin (TTX)-resistant cardiac Na+ channels are blocked by 1-10 microM TTX, whereas TTX-sensitive nerve Na+ channels are blocked by nanomolar TTX concentrations. We constructed a cDNA library from 6-day-old rat hearts, where only(More)