Several vasoselective dihydropyridine calcium channel blocker have been shown to improve PH via regulation of MMP/TIMPs: lercanidipine, showed improvement in PAH subjects by reducing serum MMP-9 levels with no modification of proMMP-2 activity or TIMP-1 level; amlodipine, administered to the monocrotaline induced PH rats was shown to inhibit MMP-2 activity, platelet activation, and plexogenic proliferation [29, 30]. This evidence concerns the gene MMP9 and pulmonary arterial hypertension.