Two components of voltage-dependent calcium influx in mouse neuroblastoma cells. Measurement with arsenazo III.

Abstract

N1E-115 mouse neuroblastoma cells were injected with the calcium indicator dye arsenazo III. Optical absorbance changes during voltage-clamp depolarization were used to examine the properties of the two calcium currents present in these cells. The rapidly inactivating calcium current (Moolenar and Spector, 1979b, Journal of Physiology, 292:307-323) inactivates by a voltage-dependent mechanism. The slowly inactivating calcium current is dominant in raising intracellular calcium during depolarizations to greater than -20 mV. Lowering the extracellular calcium concentration affects the two calcium currents unequally, with the slowly inactivating current being reduced more. Intracellular calcium falls very slowly (tau greater than 1 min) after a depolarization. The rapidly inactivating calcium current is responsible for a calcium action potential under physiological conditions. In contrast, it is unlikely that the slowly inactivating calcium current has an important electrical role. Rather, its function may be to add a further increment of calcium influx over and above the calcium influx through the rapidly inactivating calcium channels.

• Authors: S R Bolsover
• Journal: The Journal of general physiology (J Gen Physiol) Vol. 88 Issue 2 Pg. 149-65 (Aug 1986) ISSN: 0022-1295 [Print] United States
• PMID: 3746249 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Azo Compounds
• Tetraethylammonium Compounds
• Arsenazo III
• Cobalt
• Tetraethylammonium
• cobaltous chloride
• Calcium

Topics

• Animals
• Arsenazo III
• Azo Compounds
• Calcium (metabolism, pharmacology)
• Cobalt (metabolism, pharmacology)
• Electrophysiology
• Extracellular Space (metabolism)
• Mice
• Neuroblastoma (metabolism, physiopathology)
• Tetraethylammonium
• Tetraethylammonium Compounds (metabolism, pharmacology)