Kriston T, Venuto R C, Baylis C, Losonczy G
Institute of Pathophysiology, Semmelweis University Medical School, H-1445 Budapest, Hungary.
Am J Physiol. 1999 Mar;276(3):R831-7. doi: 10.1152/ajpregu.1999.276.3.R831.
The vasoconstrictor effects of pressor agents are attenuated during pregnancy. Thromboxane A2 (TXA2) is produced in great quantities during hypertension in pregnancy, and therefore it is important to know whether pregnancy modifies the pressor effects of TXA2. The TXA2 analog U-46619 was infused in anesthetized, acutely prepared and conscious, chronically prepared late-pregnant and nonpregnant female rats to examine its systemic hemodynamic and renal effects. Mean arterial pressure (MAP) and total peripheral resistance (TPR) were lower in anesthetized pregnant than nonpregnant rats (P < 0.01). The infusion of U-46619 into the aortic arch resulted in elevation of MAP only in pregnant rats, due to a greater elevation of TPR (60 +/- 17%) compared with nonpregnant rats (36 +/- 6%, P < 0.05). The pressor effect of intravenously infused U-46619 was also enhanced in conscious pregnant versus nonpregnant rats, and the increase in renal vascular resistance was undiminished. U-46619 increased hematocrit and plasma protein concentration more during pregnancy, which suggested greater reduction of plasma volume. The urinary excretion of sodium (-1.49 +/- 0.25 vs. -0.54 +/- 0.24 micromol/min) and water was reduced more in pregnant than nonpregnant rats during U-46619 (P < 0.01). Thus the MAP and renal effects of the TXA2 analog are exaggerated during pregnancy in the rat.
在孕期，升压药的血管收缩作用会减弱。血栓素A2（TXA2）在妊娠高血压期间大量产生，因此了解孕期是否会改变TXA2的升压作用很重要。将TXA2类似物U - 46619注入麻醉的、急性制备的以及清醒的、慢性制备的妊娠晚期和未妊娠雌性大鼠体内，以研究其对全身血流动力学和肾脏的影响。麻醉的妊娠大鼠的平均动脉压（MAP）和总外周阻力（TPR）低于未妊娠大鼠（P < 0.01）。将U - 46619注入主动脉弓仅使妊娠大鼠的MAP升高，这是因为与未妊娠大鼠相比，其TPR升高幅度更大（60±17% 比36±6%，P < 0.05）。与未妊娠大鼠相比，清醒的妊娠大鼠静脉注射U - 46619后的升压作用也增强，且肾血管阻力的增加未减弱。在孕期，U - 46619使血细胞比容和血浆蛋白浓度升高更多，这表明血浆量减少幅度更大。在注射U - 46619期间，妊娠大鼠的钠尿排泄量（-1.49±0.25对-0.54±0.24微摩尔/分钟）和水的排泄量比未妊娠大鼠减少更多（P < 0.01）。因此，在大鼠孕期，TXA2类似物对MAP和肾脏的影响会被放大。
