The pressure values obtained with the BP-2000 may be different than those from other machines or with different techniques (such as direct interarterial measurement). In comparison with other tail cuff systems, factors such as the diameter of the cuffs and the elasticity of the elastic may affect the overall pressure values. And tail cuff instruments may give different values than those obtained with direct measurement. These different techniques and instruments can give different average values for the same group of animals. This is why comparing BP values obtained with different tail cuff instruments, and comparing tail cuff measurements with direct interarterial measurements, is of limited value.
Thus the best approach is to look for the differences – on one instrument – between a control group and an experimental group. So for example, overall the BP-2000 may give higher or lower values than another instrument or technique, but will still show the difference between a normotensive group and a hypertensive group.
When comparing your BP results with those of another laboratory, please keep in mind that the actual values of your BP measurements can and will vary due to a number of different factors, including:
The type of cuff elastic
The diameter of the cuffs relative to the cuff elastic
The diameter of the cuff elastic relative to the tail diameter
How the cuff elastic is installed (how tight or loose)
Because of this, you should not place too much importance on the absolute value of the BP measurements (since it can vary due the factors above); the important thing is whether you can see the relative difference between two different groups (for example, a control group and a high salt group).
Your lab may get different absolute values than those of another lab, for the reasons listed above. So when comparing your results with those of another lab, the important thing to look for is whether both your lab and the other lab get a similar difference in BP values when comparing two groups. (For example, do you both see about a 20 mmHg difference between two types of mice?)