ABSTRACT
This chapter examines the evidence for the cell type responsible for lymphatic pacemaking, making frequent comparisons to pacemaking cells in the gastrointestinal (GI) tract and, to a lesser extent, cells in the cardiac conduction system. Due to an emerging appreciation of the roles for interstitial cells as pacemakers in the aforementioned tissues, some groups have hypothesized that interstitial cells of Cajal-like cells in the lymphatic wall control lymphatic pacemaking. A first step toward understanding the mechanisms underlying lymphatic pacemaking is to identify the cell type responsible for initiating spontaneous electrical activity. The proposed ionic mechanism for pacemaking in lymphatic smooth muscle was derived primarily from data recorded from guinea pig and sheep mesenteric lymphatic vessels and shares several characteristics with the ionic mechanisms in GI pacemaking cells. A major problem with distinguishing between the roles of Chloride and cation channels in lymphatic pacemaking is the lack of selective inhibitors for either class of channel.
