The use of non-invasive blood pressure measurements to measure pressor responses in rats during air stress

1. A non-invasive tail cuff method was validated against direct intra-arterial blood pressure measurements (r2 greater than 0.9) and then used to measure the systolic blood pressure (SBP) responses to air-jet stimulation in mature conscious Sprague-Dawley (SD) and spontaneously hypertensive rats (SHR). The experiments with the SHR were conducted in parallel with age matched SD rats. 2. All rats were trained to remain in perspex holders and when their SBP had stabilized, a jet of air of 10 min duration was directed at the rat's nose via rubber tubing. The blood pressure was measured during the first, fifth and tenth minute. 3. The maximum SBP response normally occurred during the first min of air-jet stimulation and averaged +30 mmHg in the SHR and +21 mmHg in the SD. Although of higher magnitude in the SHR, when expressed as a percentage of the control SBP, the rise was similar for both strains, 13% and 14%, respectively. 4. The pressor response of three SD rats stimulated daily for up to 12 days did not show any evidence of habituation to the stimulus. 5. The pressor responses to air-jet stimulation were abolished in anaesthetized rats, suggesting that they are primarily higher centre responses.