1985 Volume 56 Issue 12 Pages 954-961
The present study was undertaken to investigate mean level and variability of arterial blood pressure for 6hrs and for 3min in 9 normal unanesthetized rabbits. A large bore catheter was chronically implanted into the aortic arch via the left subclavian artery under pentobarbital anesthesia. A few days after the catheterization, when all rabbits were in a good state of health and appetite, mean arterial pressure (MAP) was sampled by an analogue to digital converter every second and stored in a digital computer. Though the mean and standard deviation in MAP for 6hrs in each record ranged widely from 73.4 to 99.2mmHg and from 5.7 to 10.0mmHg respectively, a significant negative correlation coefficient (r=-0.57) was obtained (P<0.01). The mean MAP for 3min changed little in comparison with that for 6hrs on the identical record. The variance in MAP for 3min was significantly smaller than that for 6hrs on the identical record (P<0.01). In 9 out of a total of 18 records, the histograms of MAP for 6hrs did not show normal distribution. An exaggerated mode, skewness to the right or bimodal distribution was observed. Most of the histograms of MAP for 3min were normally distributed during resting condition, whereas most of them skewed to the right or left during movement. We conclude that the responsiveness of the baroreflex system functions more powerfully in a normotensive state and that a short-term AP control is more powerful than a long-term AP control within 6hrs.
