Introduction

Substantial progress has been made in the Molecular Biology of the Na+-Ca2+ exchangers. New exchangers have been cloned and extensive alternative splicing has been described. Exons coding for different portions of the large intracellular loop are used in different combinations in different tissues. Initial work on the organization of the exchanger gene has been completed. Mutagenesis has begun to define portions of the exchanger protein involved in both ion translocation and regulation. New work was presented on the use of cell lines stably transfected with exchanger DNA. This approach should be invaluable in studying the role of the exchanger in calcium signaling pathways. Antisense oligonucleotide technology has now been applied to exchanger research; initial studies indicate this will also be a promising approach. The findings presented at the conference raise many questions which are just beginning to be addressed. What is the functional significance of the splice variants? What controls the tissue-specific expression of the Na+-Caz+ exchangers and the different splice variants? Are NCXl and NCX2 located in spatially distinct domains? Tools are now available to begin to address these and many other questions.