Arterial pressure and its variability in conscious rabbits at different ages

Mean level and its variability of mean arterial pressure (MAP) were studied in 25 unanesthetized rabbits aged 6, 12, 18, 24 and 30 months. They were selected from the same large colony and bred with an ordinary rabbit food under a given environmental conditions. MAP in the aortic arch was continuously monitored with a catheter-transducer system for 3 hrs. Mean (M) and variance (V) of MAP for 3 hrs were not significantly altered with aging (p greater than 0.05, Kruskal-Wallis' multi-sample test). Intra-animal variations of the M and SD were small. Most of histograms of MAP for 3 hrs shows an exaggerated mode at any age. Distribution pattern of the histogram was not specific to age. These suggest that responsiveness of the baroreflex system should not be affected by aging from 6 to 30 months.