Chloride currents Predicted electrochemical gradient for Cl-; opening of channels potentially leads to Cl- efflux, membrane depolarization and vasoconstriction Although ClCa has been implicated in responses to agonists or neurotransmitter stimulation, controversy remains. depolarizing effect of ClCa could be overwhelmed by the hyperpolarizing effect resulting from activation of KCa channel Volume-regulated Cl- channels are expressed in VSMC; however the current generated during volume changes are not pharmacologically identified as Cl-; therefore, the role for Cl- channels in regulating myogenic tone requires further research.