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An 'out of the box' solution to rodent NIBP

11 Oct 2012

Customer study highlights:

Erken H., Erken G., Genҫ O. (2012). Blood Pressure Measurement in Freely Moving Rats by the Tail Cuff Method. Clinical and Experimental Hypertension, 35(1):11-15 Details

Blood pressure can be measured in rodents using a range of direct and indirect methods, with differing requirements for movement restriction, anesthesia and surgery. Movement restriction can introduce stress, leading to increased blood pressure. Anesthesia also has confounding effects. Telemetry devices can be used in rodents to obtain reliable, direct blood pressure measurements, negating the need for anesthesia and movement restriction. Drawbacks with telemetry devices include the requirement for animal surgery, their limited reusability, and cost.

To achieve continuous blood pressure measurements without the use of telemetry in freely-moving rodents, researchers at Balikesir and Dumlupinar universities in Turkey devised a novel way of recording systolic blood pressure (SBP) using a hanging tail-cuff method in rats.

To observe whether this method offered any improvement in SBP over restraint conditions, 28 six-month-old male Sprague-Dawley rats were divided into four groups, with differing exposure to ether anesthesia and restraint. To acclimatize the rats, 25 minutes of daily handling was performed for one week prior to taking measurements. SBP and heart rate (HR) were recorded using a PowerLab, MLT125/R tail cuff probe and MLT422/D skin temperature probe. Desensitization of their tails with non-occluding clips was also performed. Overall SBP was obtained from an average of 10 consecutive SBP measurements per day, taken at 1 min intervals, over 3 days.

As expected, animals within the restraint group showed significantly higher SBP (+10%, day 1) and significantly lower HR (-13%, day 1) compared to rats within the freely moving group, indicating elevated stress responses. Furthermore, SBP data was more reliable in the freely moving group since handling-induced artifacts were eradicated.

This study demonstrates a reliable and novel protocol for obtaining SBP and HR from freely moving rats using the tail-cuff method, suitable for deducing both small and substantial changes in blood pressure.

By Matthew Goddard

Science Manager

Researcher, Dad and motorbike racer.