Fig. 1.

Relationship between intraluminal pressure and vascular diameter in myometrial arteries from nonpregnant and pregnant women. A and B: representative changes in vascular diameter (black line) observed with stepwise increases of intraluminal pressure (gray line) from 10 to 100 mmHg. C and D: summarized changes in diameter with increasing intraluminal pressures in Ca²⁺-containing Krebs (active) and Ca²⁺-free Krebs +40 μM diltiazem (passive) in arteries from nonpregnant (n = 10; ●, active and ○, passive) and pregnant (n = 12; ■, active and □, passive) women. Passive diameters were larger at all pressures (10 to 100 mmHg) than active diameters in arteries from both groups of women (**P < 0.01; ***P < 0.001). Data were analyzed by ANOVA doubly repeated measures where pregnancy status is the between-subjects factor and the active/passive and pressures are the two repeated factors.