Monitoring of Ca(2+)-transients in electrically stimulated A7r5 vascular smooth muscle cells fills the experimental gap between KCL-induced depolarization and patch-clamp studies.
The effects of electrical field stimulation on [Ca2+]i in the A7r5 vascular smooth muscle cell line have been monitored with the Ca(2+)-sensitive dye fura-2. The experimental set-up allowed high-temporal resolution of the [Ca2+]i-measurements and fast application of test solutions. Electrical field stimulation of A7r5 cells in the confluent growth state resulted in a transient increase in [Ca2+]i from resting values below 100 nM to values in the range of some hundred nM. For a given cell, the electrically induced Ca(2+)-transients were highly reproducible. The requirement for the presence of extracellular Ca2+ and the sensitivity to the Ca(2+)-antagonist nifedipine and the Ca(2+)-agonist BAY K 8644 suggest that the Ca(/+)-transients reflect [Ca2+]i-changes based on Ca(2+)-influx through voltage-dependent L-type Ca(2+)-channels. Therefore, electrical field stimulation of confluent A7r5 cells provides an easy-to-establish and highly reproducible method for the investigation of the physiology and pharmacology of voltage-dependent Ca(2+)-channels in intact vascular smooth muscle cells, which fills the gap between KCl-induced depolarization and the patch-clamp technique.
Kalthof
B
B
Institute for Cardiovascular and Arteriosclerosis Research, BAYER AG, Wuppertal, Federal Republic of Germany.
Bechem
M
M
Pott
L
L
Schramm
M
M
D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D002478:Cells, Cultured; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D017136:Ion Transport; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D011189:Potassium Chloride; D051381:Rats; D015203:Reproducibility of Results
D015220:Calcium Channels; D011189:Potassium Chloride; D002118:Calcium