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Updated: Aug 18, 2026

Focal Ca2+ Transient Detection in Smooth Muscle
Published on: June 29, 2009
Protein phosphatase inhibitors prolong Ca(2+)-transients and divalent cation-dependent action potentials in leech
1Department of Cell Biology and Anatomy, New York Medical College, Valhalla 10595.
Abstract:
Elevation of [K+]o for 30 s from 4 to 120 mM produced a fast and reversible depolarization and transient increase in [Ca2+]i in fura-2 loaded Retzius cells of the leech. The protein phosphatase inhibitor, okadaic acid, significantly slowed the return of [Ca2+]i toward baseline without affecting the amplitude of depolarization or rate of repolarization. Furthermore, okadaic acid and another phosphatase inhibitor, calyculin A, prolonged Ba(2+)-dependent action potentials. These results suggest that the kinetics of Ca2+ influx may be regulated by the activity of phosphatases PP-1 and/or PP-2A.
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