The prevention of Ca2+ overload in vascular smooth muscle by flunarizine as detected by Laser Microprobe Mass Analysis (LAMMA).

In vitro exposure of depolarized caudal artery preparations of the rat to a high calcium concentration resulted in a strong contraction of the smooth muscle cells. This muscle contraction was suppressed by flunarizine. It was shown cytochemically, using the combined oxalate-pyroantimonate method for the localization of calcium, that a considerable amount of electron-dense precipitate was seen over the depolarized muscle cells after incubation in a calcium containing medium. On the other hand this precipitate was not present on the smooth muscle cells when flunarizine was added to this incubation medium. The reaction product was only present in the extracellular space. These results were controlled by Laser Microprobe Mass Analysis. By evaporating and ionizing small parts of the smooth muscle cells (+/- 1 micron), it was confirmed that the cytochemical method indeed demonstrated calcium, with negligible interference of other cations.