Objectives To investigate the expression level of RAAS in endothelin-converting enzyme-1 (ECE-1) gene knockout mice and its significance.

Methods To compare RAAS expression level in ECE-1 knockout mice and wild type (WT) mice with reverse transcription polymerase chain reaction (RT-PCR). RAAS antagonist Valsartan was injected into ECE-1 knockout mice and WT mice. Systolic blood pressure and heart rate were measured before and 1-week, 2-week after drug injection.

Results The important components of RAAS [angiotensin-converting enzyme (ACE); angiotensin II type 1 receptor (AT1); angiotensinogen (AGT)] were upregdated in ECE-1 knockout mice. Systolic blood pressure of ECE-1 knockout mice was significantly decreased than WT mice after Valsartan injection (P < 0.001).

Conclusions RAAS is compensatory up-regulated when endothelin system is inhibited. It is benefit for controlling blood pressure when both RAAS and endothelin system are blockaded.