An impedance method for blood pressure measurement in awake rats without preheating.

Abstract

SUMMARY The tail-cuff methods for measuring systolic blood pressure in the rat usually require preheating of the animal to obtain recordable pulse signals. To find a more sensitive method, we applied the principle of differentiated impedance (dZ/dt) to the tail-cuff measurement of systolic blood pressure. We obtained clear pulse signals from the tail in awake rats without preheating the animals, and the systolic blood pressure obtained by this method had an excellent correlation with the directly measured femoral artery pressure (correlation coefficient = 0.98). Heating the animals at 40°C for 5 minutes increased systolic blood pressure by a mean of 6 mm Hg as compared with that determined at the ambient temperature of 21 to 24°C. Mean systolic blood pressure in young female diabetic rats was 122 ± 3 mm Hg, which was significantly higher than the 111 ± 2 mm Hg of normal rats. It is concluded that the technique of electrical impedance as applied to the tail-cuff method is simple and highly sensitive and is suitable for measurement of tail systolic blood pressure in awake rats without preheating. (Hypertension 11: 371-375, 1988) KEY WORDS • tail-cuff method • temperature effect • hypertension • diabetes mellitus N ONINVASFVE measurement of arterial pressure in small animals such as rats is hampered by the small size of the accessible peripheral arteries, which provide relatively weak pulse signals for detection. Thus, the commonly used tailcuff methods for measuring systolic blood pressure (SBP) in the rat, which employ plethysmography 13 or Doppler ultrasonic flowmeter, 4 require preheating of the animals to enhance the amplitude of pulsation in order to record the pulse signals. Such a maneuver can artificially increase SBP 3 ' 6 and, therefore, can lead to less accurate determination of SBP. The photoelectric sensor technique, 7 "" as described by Yen et al. 10 and studied by Bunag and Butterfield," does not require preheating, but a high ambient temperature is needed for reliable measurements of SBP. In the present study, we developed a relatively simple method for the

Evaluation of Blood Pressure Measured by Tail-Cuff Methods (without Heating) in Spontaneously Hypertensive Rats

“…[1][2][3][4] Several groups have attempted to develop improved tail-cuff methods, such as integrating the use of a lamp lens to localize the heating stimulus to the tail rather than to the whole animal, 7) or by employing electrical impedance to avoid animal heating altogether. 8) However, these methods still require specialized apparatus, which limits their widespread use. The goal of this study was to assess the validity of a novel tail-cuff method that does not require animal heating (method A).…”

Induction of the epithelial Na+ channel via glucocorticoids in mineralocorticoid receptor knockout mice

“…Determination of arterial blood pressure Determination of mean arterial blood pressure was performed by impedance analysis of the electrical tail resistance using tail-cuff compression [39], recently modified for mice in this institute. A lock-in amplifier was used to obtain a high resolution at the given signal-to-noise ratio [18].…”

Assisted reproductive technologies and arterial hypertension

“…AP is fixed at the moment of disappearance of the pulse wave as far as air is injected in the cuff. It was demonstrated that the results of AP measurements by the sphygmographical (indirect) method and by direct cannulation of arteries provide similar results in the studies conducted on rats (Wen et al, 1988). AP can be measured by the indirect method (by means of the cuff worn on the animal tail) both in adult rats (Bunag and Batterfield, 1982;Wen et al, 1988) and in young rats at the age 1.5 months (Amstislavsky et al, 1998) and even at the age 3 weeks (Markel et al, 1999).…”