Hart J L
Biol Res Pregnancy Perinatol. 1984;5(2):78-83.
Spontaneous activity and BaCl2 responsiveness of portal veins from non-pregnant and from 1-, 2-, and 3-week pregnant rats were compared. Isometric tension was recorded from vessels suspended in oxygenated, 37 degrees C Krebs solution. After 60-90 min equilibration, peak isometric tension, contraction frequency, and duration were measured. Then responses to cumulative additions of BaCl2 were determined. Initial isometric tension development of veins from pregnant rats was not significantly different from that of the non-pregnant rats. However, the frequency of contractions was reduced at all three stages of pregnancy and the duration of major contractions was increased. Barium caused dose-related increases in tension and reduced contraction frequencies of all vessels. Maximum increases in tension of veins from all pregnant rats were significantly less, however, than those of veins from non-pregnant rats, while barium-induced decreases in contraction frequencies were significantly greater only at 3-weeks gestation. Thus, pregnancy decreases the frequency of the spontaneous contractions of the rat portal vein throughout pregnancy, and inhibits the barium-induced increases in tension development. These changes in venous smooth muscle activity are similar to pregnancy-induced changes that have been reported to occur in arterial, uterine, and gastrointestinal smooth muscle, and may be dependent on a general smooth muscle inhibitory effect of elevated progesterone during pregnancy.
比较了未怀孕大鼠以及怀孕1周、2周和3周大鼠门静脉的自发活动和对氯化钡的反应性。从悬浮于37℃充氧的克雷布斯溶液中的血管记录等长张力。平衡60 - 90分钟后，测量等长张力峰值、收缩频率和持续时间。然后测定对累积添加氯化钡的反应。怀孕大鼠静脉的初始等长张力发展与未怀孕大鼠无显著差异。然而，在怀孕的所有三个阶段，收缩频率均降低，主要收缩的持续时间增加。钡导致所有血管的张力呈剂量相关增加且收缩频率降低。然而，所有怀孕大鼠静脉的最大张力增加显著低于未怀孕大鼠静脉，而钡诱导的收缩频率降低仅在妊娠3周时显著更大。因此，怀孕会在整个孕期降低大鼠门静脉的自发收缩频率，并抑制钡诱导的张力增加。静脉平滑肌活动的这些变化类似于已报道的在动脉、子宫和胃肠道平滑肌中发生的怀孕诱导的变化，并且可能依赖于孕期孕酮升高对平滑肌的普遍抑制作用。
