Calcium entry-dependent oscillations of cytoplasmic calcium concentration in cultured endothelial cell monolayers
RIS ID
106176
Abstract
Bovine endothelial cell monolayers grown to confluence and stimulated with bradykinin responded with periodic fluctuations in intracellular Ca2+ concentration ([Ca2+]i) when exposed to K+-free Hepes-buffered saline. The fluctuations in [Ca2+]i measured with fura-2 were synchronized among the population of cells observed and were sensitive to extracellular Ca2+ concentration ([Ca2+]o). Thapsigargin, which inhibits the endoplasmic reticular Ca2+-ATPase, did not inhibit the [Ca2+]i oscillations. Removal of extracellular Ca2+ or inhibition of Ca2+ entry by using La3+ or l-{β-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl}-1H-imidazole hydrochloride (SKF 96365) abolished the [Ca2+]i oscillations in endothelial cell monolayers. The fluctuations in [Ca2+]i were therefore dependent on Ca2+ influx rather than Ca2+ mobilization from intracellular stores. Simultaneous measurements of membrane potential (Em) using the potential-sensitive bisoxonol dye bis(1,3-dibutylbarbituric acidltrimethine oxonol [Di-BAC4(3)] and [Ca2+]i using fura-2 showed that Em oscillated at the same frequency as the fluctuations in [Ca2+]i. The peak depolarization signal coincided with the maximum rate of increase in the [Ca2+]i signal. Oscillations in the Em signal were inhibited by removal of Ca2+ or by addition of 1 mM Ni2+ to the external solution. Taken together, these observations suggest that the change in Em is the consequence of oscillatory changes in a membrane conductance that also allows Ca2+ to enter the cell. Oscillations in the DiBAC4(3) signal may reflect a rhythmic entry of Ca2+ through nonselective cation channels.
Publication Details
Laskey, R. E., Adams, D. J., Cannell, M. & Van Breemen, C. (1992). Calcium entry-dependent oscillations of cytoplasmic calcium concentration in cultured endothelial cell monolayers. Proceedings of the National Academy of Sciences of USA, 89 (5), 1690-1694.