Growing evidence exists that ATP-sensitive mitochondrial potassium channels (MitoKATP channel) are a major contributor to the cardiac protection against ischemia. Given the importance of mitochondria in the cardiac cell, we tested whether the potent and specific opener of the MitoKATP channel diazoxide attenuates the lethal injury associated with Ca2+overload. The specific aims of this study we...

The contribution of Ca2(+)-activated and delayed rectifying K+ channels to the voltage-dependent outward current involved in spike repolarization in mouse pancreatic beta-cells (Rorsman, P., and G. Trube. 1986. J. Physiol. 374:531-550) was assessed using patch-clamp techniques. A Ca2(+)-dependent component could be identified by its rapid inactivation and sensitivity to the Ca2+ channel blocker...

Canine cardiac Purkinje cells contain both L- and T-type calcium currents, yet the single Ca2+ channels have not been characterized from these cells. Additionally, previous studies have shown an overlap between the steady-state inactivation and activations curves for L-type Ca2+ currents, suggesting the presence of L-type Ca2+ "window" current. We used the on-cell, patch-clamp technique to stud...

The mechanoelectrical-transduction channel of the hair cell is permeable to both monovalent and divalent cations. Because Ca2+ entering through the transduction channel serves as a feedback signal in the adaptation process that sets the channel's open probability, an understanding of adaptation requires estimation of the magnitude of Ca2+ influx. To determine the Ca2+ current through the transd...

In MthK, a Ca2+-gated K+ channel from Methanobacterium thermoautotrophicum, eight cytoplasmic RCK domains form an octameric gating ring that controls the intracellular gate of the ion conduction pore. The binding of Ca2+ ions to the RCK domains alters the conformation of the gating ring, thereby opening the gate. In the present study, we examined the Ca2+- and pH-regulated gating and the rectif...

The effects of caffeine on cytoplasmic [Ca2+] ([Ca2+]i) and plasma membrane currents were studied in single gastric smooth muscle cells dissociated from the toad, Bufo marinus. Experiments were carried out using Fura-2 for measuring [Ca2+]i and tight-seal voltage-clamp techniques for recording membrane currents. When the membrane potential was held at -80 mV, in 15% of the cells studied caffein...

We report that a Na+-activated nonselective cation channel described previously in lobster olfactory neurons, in which phosphoinositide signaling mediates olfactory transduction, can also be activated by Ca2+. Ca2+ activates the channel in the presence of Na+, increasing the open probability of the channel with a K1/2 of 490 nM and a Hill coefficient of 1.3. Ca2+ also increases the sensitivity ...

Nicotinic acid adenine dinucleotide phosphate (NAADP) is capable of inducing global Ca2+ increases via a lysosome-associated mechanism, but the mechanism mediating NAADP-induced intracellular Ca2+ release remains unclear. The present study reconstituted and characterized a lysosomal NAADP-sensitive Ca2+ release channel using purified lysosomes from rat liver. Furthermore, the identity of lysoso...

Cytosolic free Ca2+ has been shown to have both activating and inhibitory effects upon the inositol (1,4,5) trisphosphate receptor (InsP3R) during intracellular Ca2+ release. The effects of cytosolic free Ca2+ on the InsP3R have already been monitored using cerebellar microsomes (containing InsP3R) incorporated into planar lipid bilayers [Bezprozvanny, Watras and Ehrlich (1991) Nature (London) ...

Activation of voltage-dependent Ca2+ channels (VDCCs) is critical for neurotransmitter release, neuronal excitability and postsynaptic Ca2+ signalling. Antagonists of VDCCs can be antinociceptive in different animal pain models. Neurons in lamina I of the spinal dorsal horn play a pivotal role in the processing of pain-related information, but the role of VDCCs to the activity-dependent Ca2+ in...