To determine a possible role for NCX in myogenically active smooth muscle arterioles, studies were conducted by manipulation of extracellular Na+ levels and inhibition of the exchanger. Western blotting was performed for the identification of the NCX protein. Real-time PCR was performed to demonstrate the level of expression of mRNA, for the NCX isoforms. Antisense oligonucleotides against NCX mRNA were introduced in an isolated cremaster arteriole followed by functional studies after 24 hours. Level of expression of NCX was determined by western blotting. The data are consistent with the presence of NCX1 in the cremaster arterioles.