Visceral smooth muscle cells, including vascular smooth muscle cells, possess various types of Ca channels. The voltage-dependent Ca channel is commonly observed in many tissues and is thought to play an important role in the generation of action potentials. Neural transmitters, hormones, autacoids, peptides and other substances activate individual receptors and cause activation of the receptor-operated ion channels which are permeable to Na and Ca, and in some tissues, CI ion. Thus, receptor activation may induce an influx of Ca via activation of the receptor-operated channel and voltage-dependent Ca channel, and also induce release of Ca from the sarcoplasmic reticulum (SR) via synthesis of inositol 1,4,5-trisphosphate (IP3). In addition, the concentration gradient between extra- and intra-cellular Ca (2.5 mM and 100 nM, respectively) may promote the passive influx of Ca. However, analysis of this current has not yet been made in detail. In this chapter, we discuss mainly the features of the voltage-dependent Ca channel recorded from visceral smooth muscle cells using voltage- and patch-clamp procedures, and also compare their characteristics to those in cardiac muscle cells.KeywordsSmooth Muscle CellCardiac Muscle CellSingle Smooth Muscle CellSmooth Muscle Cell MembraneSmooth Muscle MembraneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.