Cardiac calcium channels and their control by neurotransmitters and drugs.

Calcium channels, which play a primary role in the control of the calcium influx into cardiac cells, were initially studied by recording macroscopic currents in multicellular preparations. More recently, channel research has combined studies of whole cell calcium currents and elementary currents through single calcium channels, both measured in isolated cardiac cells. These studies provide insight into the mechanism of opening and closing of single calcium channels and enable inferences to be made about the whole cell calcium current from the average gating behavior of single channels. In addition, they promise a more complete understanding of the relation between the biophysical properties and molecular structure of the calcium channel. New information has also been obtained on the modulation of calcium channel gating by neurotransmitters and drugs.