In Ca2+-free solution containing endothelin-1 (ET-1), depolarization by high KCl increased the force of contraction without any changes in intracellular calcium concentration ([Ca2+]i) in canine coronary artery. The [Ca2+]i-force relationships were examined in the absence or presence of ET-1 in 5 or 90 mM KCl. The relation curve in the presence of ET-1 in 90 mM KC1-PSS was shifted to the left and upward compared with that in 5 mM KCl. These results suggest that KCl-depolarization potentiates the Ca2+ sensitization by ET-1.
- Ca2+ sensitivity
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