Figure 6

The effect of oxygen-conditioned explant medium on constriction and relaxation of myometrial arteries. Concentration–response curves for AVP-induced constriction (% of KCl constriction) (a) and BK-induced relaxation (% of maximum constriction) (b) of myometrial arteries. A 2-h incubation in either control medium (a, i; N=9, n=18) or in hypoxic-explant medium (a, ii; N=8, n=15) resulted in a significant reduction in constriction (open triangle, dotted line) compared with the preincubation curve (closed square, solid line; P<0.001, two-way ANOVA in both cases). (a, iii) Exposing the arteries to hypoxic explant medium (open triangle, dotted line) significantly shifted the concentration–response curve for AVP upwards, compared with arteries exposed to control medium (closed square, solid line; P<0.05, two-way ANOVA). Exposure of myometrial arteries for 2 h to either control medium (b, i; N=9, n=18) or hypoxic-explant medium (b, ii; N=8, n=15) (both open triangle, dotted line) resulted in enhanced vasodilatation in response to BK, compared with the pre-medium relaxation curve (closed square, solid line; P<0.001 and P<0.01, respectively, two-way ANOVA). (b, iii) The BK-induced relaxation of myometrial arteries exposed to hypoxic explant medium (open triangle, dotted line) for 2 h was significantly greater than that of vessels exposed to control medium (closed square, solid line; P<0.05, two-way ANOVA). Data are mean±s.e.m. ^*P<0.05; ^**P<0.01; ^***P<0.001.