Single nucleotide polymorphisms at codon 46 and 79 of the gene encoding for the ß2 adrenergic receptor (ß2AR) modify its pharmacological properties and may alter the response to ß2AR agonists. The goal of the present study was to evaluate the role played by the Arg16Gly and Gln27Glu polymorphisms on isoproterenol induced relaxation of internal mammary arteries segments ex-vivo.