The role of calcium-activated potassium channels in respiratory control.

The introduction of pharmacological and genetic tools has helped to understand the functional role of specific ion channel subtypes in the neural control of breathing. This review outlines the role one family of potassium channels, those, which are regulated by intracellular calcium. Calcium-activated potassium channels (K(+)ca) play important roles in determining the duration of single action potentials and in the frequency of action potentials in excitable cells. They have been classified based on their unitary conductances combined with their inhibition by a variety of pharmacologic substances. In this review the role of K(+)ca channels in respiratory control is outlined. The predictions of their contributions from modeling the respiratory system and the results of experiments in which they are individually blocked are discussed. Recently mice have been generated in which the expression of a single member of the K(+)ca channel family can be conditionally regulated. The repression of this small-conductance K(+)ca channel (SK3) as well as its overexpression affect baseline respiratory rhythm and the ventilatory response to hypoxia.