Modulation of aortic smooth muscle cell membrane potential by extracellular calcium

C. E. Palant, N. Stern, A. Meyer, M. L. Tuck

Research output: Contribution to journalArticlepeer-review


Removal of extracellular calcium may result in depolarization of the resting cell membrane potential. This has been attributed to the stabilizing action of calcium on the ionic permeability of the cell membrane. It is unknown whether this phenomenon is exclusively mediated by extracellular calcium or through associated changes in intracellular calcium. To examine this, we exposed rat aortic smooth muscle cells in culture to different calcium concentrations and studied their effects on the restidng membrane potential and intracellular calcium activity. The resting membrane potential was dependent on the extracellular potassium concentration. Exposure to reduced extracellular calcium concentrations (0.25 and 0.5 mM) caused a steep and reversible depolarization of the membrane potential, but intracellular calcium, measured with fura 2-AM, was not reduced below that measured in control conditions (1.8 mM). Atomic absorption spectrophotometric measurements did not indicate a measurable gain in cell sodium after reduction of extracellular calcium levels. We conclude that extracellular calcium controls the resting cell membrane potential of vascular smooth muscle through a mechanism that is independent of cytosolic Ca2+ activity.

Original languageEnglish
Pages (from-to)549-555
Number of pages7
Issue number5
StatePublished - 1989
Externally publishedYes


Dive into the research topics of 'Modulation of aortic smooth muscle cell membrane potential by extracellular calcium'. Together they form a unique fingerprint.

Cite this