Non-Invasive Blood Pressure (NIBP) is widely used for routine BP measurement in animals that are awake or have been anesthetized.
The basic technique is straightforward – a cuff is placed at the base of the tail and inflated to occlude blood flow, then the cuff is slowly deflated while monitoring for the return of pulsatile flow.
The cuff pressure at the time of the first appearance of the pulse indicates systolic BP. Rats and other rodents control blood flow to the tail as a means of thermoregulation. When the ambient temperature exceeds approximately 28°C-30°C, blood flow to the tail increases, making NIBP measurement easier.
Principle:
The cuff is quickly inflated to well above the suspected systolic blood pressure; the pulse will then be obliterated. Thereafter, pressure in the cuff is slowly released and, as the pressure falls below systolic blood pressure, the pulse will reappear. The method is analogous to sphygmomanometry in humans and can be applied not only at the tail of rats that are awake, but also in dogs and small primates. The indirect tail cuff method is widely used to evaluate the influence of antihypertensive drugs in spontaneously and experimentally hypertensive rats.
Test Procedure:
ADVERTISEMENTS:
i. Male spontaneous hypertensive rats weighing 300-350 gm, or rats or mice with experimentally induced hypertension are used.
ii. To measure blood pressure, a tubular inflatable cuff is placed around the base of the tail and a piezo-electric pulse detector is positioned distal to the cuff.
iii. The cuff is inflated to approximately 300 mm Hg. As the pressure in the cuff is slowly released, the systolic pressure is detected and subsequently recorded on a polygraph.
iv. The test substance is administered intraperitoneally or by gavage once per day over a period of 5 days.
ADVERTISEMENTS:
v. The usual screening dose of a new compound is 25 mg/kg.
Standard Compounds:
1. Endralazine (3 mg/kg p.o.)
2. Nifedipine (3 mg/kg p.o.)
ADVERTISEMENTS:
3. Urapidil (5 mg/kg p.o.)