The goal of these studies was to determine if different calcium channel antagonists affect glucose transport in a neuronal cell line. For these studies, rat pheochromocytoma (PC12) cells were treated with L-, Tand N-type calcium channel antagonists prior to measuring the accumulation of H-2-deoxyglucose (H-2-DOG). The L-type channel antagonists, nimodipine, nifedipine, verapamil, and diltiazem ...

Aberrant activation of mast cells contributes to the development of numerous diseases including cancer, autoimmune disorders, as well as diabetes and its complications. The influx of extracellular calcium via the highly calcium selective calcium-release activated calcium (CRAC) channel controls mast cell functions. Intracellular calcium homeostasis in mast cells can be maintained via the modula...

The quantitative relationship between presynaptic calcium influx and transmitter release critically depends on the spatial coupling of presynaptic calcium channels to synaptic vesicles. When there is a close association between calcium channels and synaptic vesicles, the flux through a single open calcium channel may be sufficient to trigger transmitter release. With increasing spatial distance...

The modulation by internal free [Mg2+] of spontaneous calcium release events (Ca2+ "sparks") from the sarcoplasmic reticulum (SR) was studied in depolarized notched frog skeletal muscle fibers using a laser scanning confocal microscope in line-scan mode (x vs. t). Over the range of [Mg2+] from 0.13 to 1.86 mM, decreasing the [Mg2+] induced an increase in the frequency of calcium release events ...

Polycystin-2, the product of the gene mutated in type 2 autosomal dominant polycystic kidney disease (ADPKD), is the prototypical member of a subfamily of the transient receptor potential (TRP) channel superfamily, which is expressed abundantly in the endoplasmic reticulum (ER) membrane. Here, we show by single channel studies that polycystin-2 behaves as a calcium-activated, high conductance E...

Native T-type voltage-dependent calcium channels are low voltage-activated and have a small single channel conductance of 5-8 pS, which distinguishes them from any known cloned calcium channels whose conductances are 12-25 pS. Here, we show that when alpha1B, alpha1E, or alpha1C are expressed in COS7 cells, which contain no endogenous calcium channel subunits or calcium channels, they each exhi...

Zinniol [1,2-bis(hydroxymethyl)-3-methoxy-4-methyl-5-(3-methyl-2-butenyloxy)benzene], a toxin produced by fungi of the Alternaria group, causes symptoms in plants that resemble those induced by the fungi. The phytotoxin binds to carrot protoplasts and isolated membranes in a saturable and reversible manner. Receptor occupancy stimulates entry of calcium into protoplasts. Zinniol can partially r...

The M current regulates neuronal excitability, with its amplitude resulting from high open probability modal M channel behavior. The M current is affected by changing intracellular calcium levels. It is proposed that internal calcium acts by regulating M channel modal gating. Intracellular application of a preactivated form of the calcium-dependent phosphatase calcineurin (CaN420) inhibited the...

Progress in ophthalmology is accompanying with nonophthalmic drug use. Calcium channel blockers, which alter the intracellular calcium concentration by modifying calcium flux across cell membranes and affect various intracellular signaling processes, have been long and widely used to treat essential hypertension and certain types of cardiac diseases such as angina pectoris. Among five subtypes ...

Calcium fluxes have been implicated in the specification of the vertebrate embryonic nervous system for some time, but how these fluxes are regulated and how they relate to the rest of the neural induction cascade is unknown. Here we describe Calfacilitin, a transmembrane calcium channel facilitator that increases calcium flux by generating a larger window current and slowing inactivation of th...