Telemetric monitoring of adrenocorticotrophin-induced hypertension in mice.

1. The mouse is the animal of choice for studies involving genetic manipulation and transgenic and knockout mice are valuable tools for physiological studies. We have studied adrenocorticotrophin (ACTH)- and steroid-induced hypertension in both rat and humans. The aim of the present study was to develop a model of ACTH-induced hypertension in the mouse and to assess a chronically implanted telemetric device for measurement of blood pressure (BP). 2. Male Swiss Outbred and Quackenbush Swiss (QS) mice (35-45 g) were implanted with TA11PA-C20 BP devices (Data Sciences International, St Paul, MN, USA) under isoflurane anaesthesia. Seven to 10 days later, mice were monitored telemetrically for baseline BP for 4 days. Mice were then randomly allocated to: (i) sham treatment with normal saline s.c.; or (ii) ACTH at 500 microg/kg per day, s.c. Mice were monitored 24 h/day for 10 days. 3. Sham treatment (n = 7) did not affect BP (114 +/- 2/84 +/- 1 to 115 +/- 2/84 +/- 1 mmHg; P = NS). Adrenocorticotrophin treatment (n = 5) raised BP from 112 +/- 7/82 +/- 4 to 138 +/- 3/104 +/- 4 mmHg, which was significantly different from sham treatment (P = 0.0021 for systolic BP; P < 0.0001 diastolic BP). The increase in BP with ACTH was comparable with that seen in previous studies in humans, sheep and rat. Sham and ACTH-treated animals each lost 3% bodyweight. 4. Administration of ACTH (500 microg/kg per day) raises BP in two strains of mice, measured using a telemetry system. This model will allow the selective use of transgenic and/or knockout mice to further elucidate the mechanism of ACTH- and steroid-induced hypertension.