Contractile effects of vanadate on aorta rings from virgin and pregnant rats |
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Authors: | Jean St-Louis Benoit Sicotte Eric Breton Ashok K. Srivastava |
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Affiliation: | (1) Centres de recherche, Hôpital Ste-Justine, 3175 Chemin Côte Ste-Catherine, H3T 1C5 Montréal, Qc, Canada;(2) Hôpital Hotel-Dieu de Montréal, H3T 1C5 Montréal, Qc, Canada;(3) Department of Obstetrics and Gynecology, University of Montréal, H3T 1C5 Montréal, Qc, Canada;(4) Department of Medicine, University of Montréal, H3T 1C5 Montréal, Qc, Canada |
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Abstract: | The present study was undertaken to characterize the contractile effects of vanadate on thoracic aorta rings from virgin and term-pregnant rats. Vanadate caused concentration-dependent contraction in rat aortic rings with an EC50 (concentration producing 50% maximum response) of 0.10 mM. Contractions in response to vanadate were equivalent to the ones measured with 1 M phenylephrine. The effects of vanadate were not affected by indomethacin (up to 10 M), an inhibitor of prostanoid cyclooxygenase, but were blocked in a concentration-dependent manner by staurosporine (0.1–1.0 M), an inhibitor of protein kinase C. Vanadate exhibited a significant decrease of contractile responses in aorta of pregnant as compared to virgin rats. When aortic rings were bathed in presence of different concentrations of vanadate, the concentration-response curve to phenylephrine was shifted to the left, but maximum response was not affected. The potentiation of the contractions to phenylephrine by vanadate was significantly more prominent in aorta of virgin than of pregnant rats. These results suggest that the contractile effect of vanadate on rat aorta is independent of endogenous prostanoids and may be mediated by protein kinase C-dependent pathway. These results also show that the contractile response to vanadate on the rat aorta is impaired during pregnancy. |
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Keywords: | vanadate pregnancy vascular smooth muscle staurosporine |
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