Understanding of the electrophysiological properties of the calcium channel in cardiac cell membranes has been hampered because of the difficulties in interpreting voltage-clamp data. Recently, new techniques for isolation of adult heart cells, internal dialyzation of the cell and analysis of the single ion channel current have been established. Some of the previous results and concepts obtained in intact cardiac tissues have been confirmed and new understanding of the nature of the calcium channels has been gained by the techniques. In this article, the author reviews the electrophysiological and electropharmacological properties of the calcium ion channels in cardiac cell membranes. Especially, emphasis is placed on new information gleaned from the new techniques.
The nicotinic acetylcholine receptors present in the mammalian brain have received less attention than those in other areas of the nervous system. However, recent studies have reported the pharmacological character and regional distribution of a high-affinity binding of [3H]acetylcholine or[3H]nicotine. In this review, the pharmacological characters and physiological functions of the brain nicotinic receptors were discussed with special reference to central cardiovascular regulation.