A new method for measurement of blood pressure, heart rate, and activity in the mouse by radiotelemetry

1 Data Sciences International, St. Paul, Minnesota 55126; 2 IBIS Instrumentation Canada, Ottawa, Ontario, Canada K1Z 7Z3; 3 Mayo Clinic, Rochester, Minnesota 55905; and 4 Department of Pharmacochemistry, Division of Molecular Pharmacology, Leiden/Amsterdam Center for Drug Research, Free University, 1081 HV Amsterdam, The Netherlands A simple and reliable means for accurate, chronic measurement of pulsatile blood pressure (BP) from conscious, freely moving laboratory mice was developed and validated. The newly developed device consists of a small (1.9 ml, 3.4 g), fully implantable radiotelemetry transmitter. Initial frequency response tests showed an adequate dynamic response; the average 3-dB point found in five transmitters was 145 ± 14 (SD) Hz. BP, heart rate, and locomotor activity were recorded from 16 chronically (30-150 days) implanted mice. Mean arterial and pulse pressure, checked at regular intervals, ranged from 90-140 mmHg and from 30-50 mmHg, respectively, throughout the study. Transmitter BP measurements were validated against a Millar 1.4-Fr. transducer-tipped catheter. The mean error of the transmitters for diastolic pressures was +1.1 ± 6.9 mmHg ( n = 7). The error for systolic pressures was, on average, 2.7 ± 3.9 mmHg larger. This new device accurately monitors BP, heart rate, and locomotor activity in conscious, untethered, freely moving mice living in their home cages for periods of at least 150 days. conscious animals; chronic implant; frequency response; biocompatibility