Arbind,

I'd say that there's no simple way to measure blood pressure invasively. The gold standard for this method is via implantation of a radiotelemetry device, with the probe usually in the arch of the aorta, descending from one of the carotids. This is a complex surgery and requires a great deal of skill. However, it does of course provide excellent data as it measures haemodynamic parameters in an unrestrained animal over long periods of time. This may be an easier technique to perform in rats.

Non-invasively, one can measure BP via tail cuff volume pressure recording. This is not considered to be as good a measure for BP but there is good correlation between data obtained by this technique and that obtained from telemetry. It requires less skill and is considerably cheaper, once the initial equipment has been purchased. We use both techniques in our lab and have recently published in the Journal of Hypertension using tail cuff as our primary measure of BP (see Smillie et al., Hypertension, 2014). If you're doing initial phenotyping, I would recommend starting with tail cuff and perhaps validating any interesting results by telemetry.

Hope this helps,

Ross

Are you talking about on human patients or laboratory animals? You can always put in an arterial line with pressure transducer hook-up with the plethysmography to monitor BP in real-time. But you do need to know how to calibrate and zero the machine. You can blindly insert the angiocatheter into an artery or do cut-down. Blind insertion is simple but needs a lot of practice.

Insert an arterial catheter and measure the blood pressure like in the intensive care unit in human.

Millar or Scisence pressure catheters into the carotid measure blood pressure (not for clinical use!)

Arbind,

Intra-arterial cannulation with connection to pressure transducers provides reliable and continuous recording of blood pressure in rats. I would recommend insertion via the common carotid (under anaesthesia) and dependent upon how long you need to record the BP and the physiological state you plan to investigate will dictate how to best exteriorise the catheter. For example, for sampling/recording of BP in conscious, unanaesthetised rats without handling, I suggest considering externalising at the base of the tail then covering the vulnerable cannula (rats will chew the polyethylene and could exsanguinate) and run it up the tail using a semi tethered model. Keeping the cannula line clear, you could measure continuously, without having to handle your rat, for long periods (over month or more). Inclusion of a t-piece tap in the line permits flushing of the line and arterial sampling and arterial administration of medication or replacement blood if sampling. For shorter term studies where handling the rat is not an issue, consider externalising the cannula between the scapulae on dorsal thoracic region (runs via tunnel from common carotid).