Aim: 

Urotensin-II is a vasoactive peptide with many effects in the cardiovascular system. Urotensin-II has been described to induce potent artery vasoconstriction and to stimulate heart remodelling and vascular smooth muscle cell proliferation. Moreover, store-operated channels activation and Ca²⁺ independent phosholipase-A₂ have been shown to play a critical role in the regulation of vascular tone. The aim of this study is to characterize the signalling pathway involved in urotensin-II induced vasoconstriction and smooth muscle cells proliferation.

Methods: 

Vascular tone was studied in thoracic aorta dissected from Wistar rats in an organ chamber (Cibertec). And AlamarBlue reactive was used to evaluate the proliferation in aortic smooth muscle primary culture.

Results: 

Urotensin-II produced a dose dependent contraction of aorta and maximum effect was observed when 100 nM urotensin-II was applied. Specific inhibitors of the store-operated channels and phospholipase-A₂ produced a strong vasodilatation of urotensin-II precontracted arteries indicating its participation in urotensin-II regulation of aortic vascular tone.

On the other hand, urotensin-II induced the proliferation of smooth muscle cells that depends on Ca²⁺ entry through store-operated channels and on phospholipase-A₂ activation.

Conclusion: 

Our preliminary data show an important role of store-operated channels, and phospholipase-A₂, in urotensin-II induced smooth muscle vasoconstriction and cell proliferation.

Acknowledgements: 

This study was supported by Consejería de Innovación y Ciencias de la Junta de Andalucía "P08-CVI-3913". T.S is a "Ramón y Cajal" Researcher and M.R is a fellow of Fundación Reina Mercedes.