Long-term telemetric recording of arterial pressure and heart rate in micefed basal and high NaCl diets

Research examining the control of arterial pressure in mice has primarily r elied on tail-cuff plethysmography and, more recently, on tethered arterial catheters. In contrast, the radiotelemetry method has largely become the " gold standard" for long-term monitoring of arterial pressure and heart rate in rats. Whereas smaller telemetry probes have recently been developed, no published studies have used radiotelemetric monitoring of arterial pressur e in mice, largely because of a relatively low success rate in small mice ( ie, <30 g body weight). We report on the development of a protocol for the use of these probes to continuously monitor arterial pressure and heart rat e in mice as small as 19 g body weight. To test the accuracy and reliabilit y of this method, adult C57/BL6 mice were monitored for 3 weeks during expo sure to a basal followed by a high NaCl diet. The results demonstrate that carotid and aortic placements of the telemetry probe provide equally accura te monitoring of arterial pressure and heart rate, but the carotid placemen t has a much greater rate of success. Exposure to a high NaCl diet increase s both the amplitude of the arterial pressure rhythm (+ 6.0+/-0.6 mm Hg, ap proximate to 32%) and the average mean arterial pressure (+ 8.6+/-1.1 mm Hg , approximate to 8%), as would be predicted from previous studies in NaCl-r esistant rats. Thus, the data demonstrate that telemetric recording of long -term arterial pressure and heart rate provides a powerful tool with which to define the mechanisms of cardiovascular control in mice.