Since antisense oligodeoxynucleotides (AS-ODNs) have been recognized as a new generation of putative therapeutic agents, we established a delivery technique that could transfect AS-ODNs, which are designed for endothelin type B receptor (ETB), into cultured human coronary endothelial cells (HCECs) by exposure to ultrasound in the presence of echo contrast microbubbles. Ultrasound offers several advantages such as being nontoxic, nonantigenic and providing rapid gene transfer. We standardized the optimal conditions, which consisted of 2 x 106 cells suspended in phosphate buffer with 900 nM ODN, 50 mul of echo contrast microbubbles (Optison), and ultrasound exposure (1.0 W/cm(2), 10% duty cycle, and 10 s duration). The percentage of transfected cells was 25.2 +/- 2.0% after ultrasound treatment. This is the first demonstration of the use of the ultrasound exposure technique in conjunction with microbubbles in HCECs. (C) 2002 Elsevier Science (USA). All rights reserved.