Blood pressure and heart rate
Conditions: For drinking water, mice were given either tap water or 1% NaCl (in tap water) 2 wks prior to and during the testing period.
Equipment: BP-2000 Blood Pressure Analysis System (Visitech Systems, Apex, NC, USA). This machine has four restraining units (dark metal tunnels open at one end) and a 37°C warming plate. Computer-automated tail cuffs inflate and deflate rapidly. Pressure is detected by a photo-resister cell below each tail and is recorded (computer-assisted data collection).
Reagents: NaCl from American Bioanalytical (#AB13214)
Animal preparation: Mice were habituated for 7 days on the equipment prior to testing.
Running: Tail cuffs were placed on the tails of each of four mice. Blood pressure and heart rate were determined and recorded. Mice were tested over three days and 20 measurements per day were collected (see below).
Data collection and analysis: For each mouse, if the standard deviation over the course of a day exceeded 15 mm Hg, the data was discarded.
Investigator notes: This non-invasive method was verified by comparing to an intra-arterial blood pressure method involving anesthetization and catheterization.