Key result
E-4031 induced phasic contractions or significantly increased the amplitude of phasic contractions in spontaneously active gallbladder smooth muscle tissues (P = 0.001).
Why the study?
Does ERG1 channel blockade with E-4031 or cisapride modulate the electrical and contractile activities of gallbladder smooth muscle?
Does ERG1 channel blockade with E-4031 or cisapride modulate the electrical and contractile activities of gallbladder smooth muscle?
ERG1 channels are expressed in gallbladder smooth muscle and play a key role in excitation-contraction coupling by contributing to repolarization and resting membrane potential.
Supports ERG1 regulation of gallbladder contractility in animals; leaves open human motility implications.
The current study was undertaken to test the existence and possible role of ether-a-go-go-related gene 1 (ERG1) protein K(+) channels in gallbladder smooth muscle (GBSM). Transcripts encoding ERG1 were detected in human, mouse, and guinea pig GBSM, and ERG1 immunoreactivity was observed in GBSM cells. In intracellular voltage recordings, addition of E-4031 (100 nM-1 microM) or cisapride (100 nM-2 microM) caused concentration-dependent excitation of guinea pig GBSM that was not affected by 500 nM TTX + 5 microM atropine, and E-4031 also depolarized the resting membrane potential. In muscle strip studies, E-4031 either induced phasic contractions or significantly increased the amplitude of phasic contractions in spontaneously active tissues (P = 0.001). E-4031 also potentiated bethanechol-induced contractions. In conclusion, ERG1 channels are expressed in the GBSM, where they play a role in excitation-contraction coupling probably by contributing to repolarization of the plateau phase of the action potential and to the resting membrane potential.
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Parr et al. (2003) studied Gallbladder smooth muscle physiology. E-4031 or cisapride was evaluated on Electrical and contractile activities (phasic contractions) (p=0.001). E-4031 induced phasic contractions or significantly increased the amplitude of phasic contractions in spontaneously active gallbladder smooth muscle tissues (P = 0.001).
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