Molecular pharmacology of the amiloride analog 3-amino-6-chloro-5-[(4- chloro-benzyl)amino]-N-[[(2,4-dimethylbenzyl)-amino]iminomethyl] -pyrazinecarboxamide (CB-DMB) as a pan inhibitor of the Na+-Ca 2+ exchanger isoforms NCX1, NCX2, and NCX3 in stably tra