[Which basal tension for the study of aortic reactivity in pregnant Wistar rats?]

Basal tension for optimal contraction either for a maximal contraction in pregnant Wistar rat is not well know. Our study aims to determinate the optimal basal tension for the study of aortic contraction in pregnant Wistar rat. The stability of vessels tone depending on basal tension was also determinate. Aortic rings with endothelial cells from non-pregnant and 20-day pregnant Wistar rats were used. Rings with different basal tensions of 1 g, 1.5 g, 2 g or 2.5 g were contracted with KCl at 100 mmol/l or norepinephrine in a cumulative manner (10-9M à 3.10-5M). Our results show, at least, one hour of stability for all basal tensions. On the other hand, contractions raise in a significant manner depending in basal tension either with KCl or norepinephrine. However, There is no significant difference in contractions with the basal tensions of 2 g and 2.5 g except in pregnant rats where vessels were contracted with norepinephrine. These results suggest that basal tension of 2 g would be used for the study of aortic reactivity in pregnant Wistar rat because it allows a good stability, the tension is practically optimal in pregnant and non-pregnant rats with any contracting agent and this tension is most commonly used.