Measurement of blood pressure
In conscious rats, mean arterial pressure (MAP) was simultaneously monitored by noninvasive tail-cuff system (ALC-NIBP, Shanghai Alcott Biotech) as described by previously (Fraser et al., 2001; Zha et al., 2013). The rats were restricted by a recording chamber for 15 minutes before measurement of MAP to make the rat acclimate the holding device, and to keep rat quiet and comfortable during the whole process. In addition, retaining the ambient temperature of 37°C in chamber with controlled warming plate under the rats is beneficial to for vasodilation of the tail artery. The values resulted from averaging of at least six consecutive measurements, and MAP was measured every week or every 2 days after treatments.
On GD 20.5, arterial blood pressure measurement was performed as described previously (Zha et al., 2013). Briefly, the pregnant rats were anaesthetized (urethane 800 mg/kg and alpha-chloralose 40 mg/kg, i.p.), and then the right carotid artery was catheterized. The systolic blood pressure was determined by the PowerLab system (AD Instruments, Australia).