Endothelins (ETs) are potent vasoconstrictors known to play a role in tissue remodeling after vascular wall injury. The molecular mechanisms for the expression and functions of ETs and their receptors after carotid artery angioplasty are not fully understood. Using quantitative reverse transcription and polymerase chain reaction, the present study demonstrates the temporal mRNA expression of ET-converting enzyme-1 (ECE-1), preproET-1, preproET-3, and both ETA and ETB receptors after rat carotid artery balloon angioplasty. A significant increase in ECE-1 mRNA was observed at 6 hours (1.8-fold increase over control, P < .01) and 24 hours (1.7-fold increase, P < .01) in carotid arteries after angioplasty. In contrast, a significant increase in preproET-1 mRNA levels was not observed until 3 days (1.9-fold increase, P < .05) and 7 days (2.1-fold increase, P < .05). A similarly delayed increase in preproET-3 mRNA was observed at 7 days (2.8-fold increase, P < .05) and 14 days (2.6-fold increase, P < .05) after angioplasty. A parallel but marked increase in ETA and ETB receptor mRNAs compared with preproET-1 and -3 messages was observed after angioplasty. The levels of ETA receptor mRNA were elevated 29.3-fold (P < .001) and 24.3-fold (P < .01) at 3 and 7 days, respectively, after angioplasty. The increase in ETB receptor mRNA occurred slightly earlier than the increase in ETA receptor mRNA, showing 15.1-fold increase at 1 day (P < .001) and 11.3-fold increase at 3 days (P < .01) after angioplasty. Immunohistochemical studies using anti-ET antibodies demonstrated a corresponding increase in ET immunoactivity, which was distributed mainly in the neointimal cells 14 days after angioplasty. The increases in ECE-1, ET-1, and ET-3 and their receptor expression after balloon angioplasty suggest that these proteins play an active role in the pathogenesis of neointimal formation.