Single pressure injections of 1-2 mM calcium aspartate into the light-sensitive region of Limulus ventral photoreceptors resulted in a rapid, 20-40-mV depolarization lasting approximately 2 s. The depolarization closely followed the rise in intracellular free calcium caused by the injection, as indicated by aequorin luminescence. The depolarization was followed by reversible desensitization (ad...

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Introduction: The functional effects of orexin-B on the calcium spikes and excitability of the neuronal soma membrane of garden snail, Helix aspersa were studied. Methods: Conventional intracellular recording, under the current clamp conditions was performed to examine the effects of orexin-B on the configuration and electrophysiological properties of calcium spikes. Results: Application o...

Large cell motoneurons in the Cancer borealis cardiac ganglion generate rhythmic bursts of action potentials responsible for cardiac contractions. While it is well known that these burst potentials are dependent on coordinated interactions among depolarizing and hyperpolarizing conductances, the depolarizing currents present in these cells, and their biophysical characteristics, have not been t...

A slowly inactivating inward calcium current was identified in the rat osteosarcoma cell line ROS 17/2.8 using a combination of ion flux and electrophysiological techniques. Voltage dependence, dihydropyridine sensitivity, divalent cation selectivity, and single channel properties identified this current as a high threshold, "L-type" calcium current. Ion flux experiments using 45Ca2+ confirmed ...

Somatostatin is a neurohormone peptide that inhibits a variety of secretory responses in different cell types. We have investigated the effects of somatostatin on calcium current and intracellular free calcium in AtT-20 cells, a pituitary tumor line in which the inhibitory actions of this peptide have been well characterized. At concentrations similar to those that inhibit adrenocorticotropic h...

External or internal application of proton on the calcium current was investigated using the whole-cell patch clamp technique in single ventricular cells of the guinea pig. The effect of acid pHo on the calcium current depended on the strength of the buffer in the internal solution. In the presence of 5 mM HEPES in the pipette, external acidification depressed calcium current with the half maxi...