Abstract:OBJECTIVE: It is known that Notch signal is very important to vascular remodeling during the process of embryonic development, vessel repair and tumor growth, but there are few studies about pulmonary vascular remodeling in pulmonary hypertension. This study was to explore the effect of inhibiting Notch signal on pulmonary vascular remodeling induced by angiotensin Ⅱ. METHODS: Vessel strips taken from healthy Wistar rats were co-cultured with extrogenous angiotensin Ⅱand the potent smooth muscle cell proliferation stimulators for 7 days. Vascular wall thickness, proliferating cell nuclear antigen (PCNA) positive cell rate and caspase-3 positive cell rate were examined in vessel strips. Then some vessel strips were cultured with angiotensin Ⅱ and γ-secretase inhibitor DAPT, a Notch signaling inhibitor for 7 days. The levels of Notch 1 to 4 receptor and HERP1/2 mRNA were ascertained by FQ-PCR. RESULTS: Angiotensin Ⅱstimulation in the cultured normal pulmonary arteries resulted in an increase in the vascular medial thickness by nearly 50%, and a significant increase in the PCNA positive cell rate and a decrease in the caspase-3 positive cell rate. DAPT treatment did not result in the alterations of Notch 1 to 4 receptor levels, but decreased remarkably HERP1 and HERP2 mRNA expression. DAPT treatment also decreased angiotensin Ⅱ-induced vascular medial thickness and PCNA positive cell rate and increased caspase-3 positive cell rate. CONCLUSIONS: Inhibiting Notch signal by γ-secretase inhibitor may lead to the suppression of pulmonary vascular remodeling induced by angiotensin Ⅱ, suggesting that the inhibition of Notch signal pathway might be a novel strategy for the treatment of pulmonary hypertension.
