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Vasopressin responses in electrically coupled A7r5 cells
L Missiaen1, M Oike, M D Bootman
1Laboratorium voor Fysiologie, K. U. Leuven Campus Gasthuisberg, Belgium.
Pflugers Archiv : European Journal of Physiology
|October 1, 1994
Summary
Spontaneous calcium oscillations in smooth muscle cells are synchronized due to electrical coupling. Arginine vasopressin stimulation causes asynchronous calcium increases and halts spontaneous activity.
Area of Science:
- Cellular physiology
- Smooth muscle biology
- Calcium signaling
Background:
- A7r5 smooth muscle cells exhibit spontaneous electrical and calcium activity.
- Electrical coupling synchronizes cellular behavior in confluent monolayers.
Purpose of the Study:
- To investigate cytosolic Ca2+ concentration ([Ca2+]i) and membrane potential changes in A7r5 cells.
- To analyze the effects of arginine vasopressin on spontaneous activity and Ca2+ signaling.
Main Methods:
- Monitoring [Ca2+]i and membrane potential in single A7r5 cells.
- Stimulating cells with arginine vasopressin.
- Observing spontaneous Ca2+ oscillations and action potentials.
Main Results:
- ~90% of confluent A7r5 monolayers showed synchronized spontaneous Ca2+ oscillations and action potentials.
- Arginine vasopressin elevated [Ca2+]i ~5-fold, causing a sustained cessation of spontaneous activity.
- Agonist-induced Ca2+ waves propagated slower than spontaneous rises, and cellular responses to vasopressin showed variable latency.
Conclusions:
- A7r5 cells in confluent monolayers are electrically coupled, leading to synchronized spontaneous activity.
- Arginine vasopressin disrupts synchronized activity by inducing asynchronous [Ca2+]i increases.
- Agonist-induced Ca2+ signaling in electrically coupled cells can be asynchronous.