Long-term analysis of the hypertension produced by sinoaortic denervation in the rat

The increases in pressure lability and in mean arterial pressure (MAP) produced by sinoaortic denervation (SAD) in the rat were studied during a 16 h period of continuous pressure measurement 1, 7, 15, 30, 90 and 180 days after surgery. All groups of SAD rats showed increased pressure lability that was estimated from the standard deviation of approximately 960 pressure values taken one per min from the continuous record. The average standard deviation increased 40-90% and the distribution curves of pressure during the 16 h period was wider in the group of SAD rats than in the controls. Although the increased lability of SAD rats remained unchanged, the average minute-to-minute increase in MAP declined during the postoperative period studied. MAP dropped from 151 +/- 5 mmHg (vs 114 +/- 1 mmHg for the control) on the 1st day to 141 +/- 3, 135 +/- 3, 133 +/- 2, 132 +/- 2 and 130 +/- 2 mmHg on days 7, 15, 30, 90 and 180 after SAD, respectively. Movement-related pressure dips were observed in the SAD rats monitored for 16 h in contrast to the other natural states of behavior (walking, eating, grooming) that usually produced an increase in the MAP of control rats and tended to produce exaggerated pressor responses in SAD rats. SAD rats showed increased pressure lability and an elevation of MAP from 130-135 mmHg to 150 mmHg for up to 10 min in response to an acoustic stimulus. The data demonstrate the importance of using quiet and undisturbed conditions to assess the true pressure increase produced in rats by sinoaortic denervation.(ABSTRACT TRUNCATED AT 250 WORDS)