1. Mean arterial pressure was determined continuously over a 24-h period by computerized data collection in eight control and nine sinoaortic-denervated rats housed in standard-sized metabolic cages. In addition, direct and indirect pressure measurements were made while the rats were resting in a Lucite restrainer.
2. Pressure measurements made during restraint indicated that the baroreceptor-denervated rats were hypertensive: mean aortic pressure averaged 145 ± 3.4 mmHg (mean ± sem) in denervated rats vs 119 ± 2.8 mmHg in control rats (P<0.001), and tail-cuff pressure averaged 156 ± 5.4 mmHg compared with 121 ± 2.7 mmHg in the control group (P<0.001).
3. In contrast, continuous pressure monitoring showed the sinoaortic-denervated rats were normotensive (mean arterial pressure averaged 119 ± 4.7 mmHg vs 119 ± 3.1 mmHg in control rats).
4. Apparently arterial pressure is elevated during restraint in sinoaortic-denervated rats and pressure measurements made under these conditions give a false indication of hypertension.