ABSTRACT
The application of patch-clamp electrophysiology to single smooth muscle cell preparations is generating a bewildering wealth of information about K +currents in vascular muscle cell membranes as it is in many other excitable cells. Functional studies such as these are hampered by a lack of a comprehensive range of specific pharmacological probes to clearly identify K + currents. Aside from specific agents such as charybdotoxin and the relatively selective glibenclamide, many studies attempt to draw conclusions from data using tetraethylammonium (TEA) and 4aminopyridine (4-AP), compounds with a broad K channel blocking profile. The recent advances in the molecular biology of K channels now provides the opportunity to put the functional studies into a structural framework and hopefully reveal a little more order. In this chapter we will consider work using both approaches in an effort to develop an overall picture of these channels in vascular smooth muscle. This information will then be used to consider the likely sites of action of the K channel openers, a group of compounds that have attracted interest both because of their therapeutic potential and because of the insights they have provided on vascular smooth muscle function.
