Butz G M, Davisson R L
Department of Anatomy and Cell Biology, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
Physiol Genomics. 2001 Mar 8;5(2):89-97. doi: 10.1152/physiolgenomics.2001.5.2.89.
The recent miniaturization of implantable radiotelemetric devices offers the possibility of an accurate, reliable, and simple phenotyping tool for long-term, hands-off measurement of blood pressure in unrestrained, untethered mice; however, use has been limited because of high morbidity and mortality in all but larger-than-average mice. Also, because the device was developed for abdominal aorta implantation at the renal artery level, its use has not been feasible in studies where infrarenal blood flow is critical, i.e., in pregnant mice. We provide details of a very successful alternative approach for implanting radiotelemeters in mice, whereby thoracic aortic implantation of the pressure-sensing catheter is combined with subcutaneous placement of the transmitter body along the right flank. We used female C57/BL6 (C57) or BPH/5 mice, a strain derived from the cross of inbred hypertensive and hypotensive mouse strains. We show that this is a reliable procedure for providing high-fidelity mean arterial pressure (MAP) and heart rate (HR) recordings for 50-60 days in mice weighing 22 g on average but as small as 17 g. No morbidity or mortality was observed in either strain using this procedure. Importantly, neither strain fully recovered from anesthesia and surgery, as indicated by a return of normal circadian rhythms, until 5-7 days postsurgery. This was also reflected in significantly elevated baseline MAP and HR levels in both strains during this recovery period. Moreover, strain-related differences in relative increases in MAP during the first 5 days of recovery masked the significant elevation in BPH/5 baseline MAP (vs. C57) observed in fully recovered mice. This suggests that methods must allow at least 5-7 days recovery from surgery to provide accurate cardiovascular (CV) phenotyping in mice. Finally, we show that CV parameters can be monitored continuously before, during, and after pregnancy in mice using this alternative implantation approach. The device did not interfere with conception, gestation, delivery, or postnatal care of pups. These results demonstrate the feasibility of stress-free, long-term monitoring of CV parameters in pregnant or nonpregnant mice of typical size and offer exciting possibilities for application in CV functional genomic research.
近期可植入式无线电遥测设备的小型化，为在不受束缚、无连接的小鼠中进行长期、无需人工干预的血压测量提供了一种准确、可靠且简单的表型分析工具；然而，除了体型大于平均水平的小鼠外，该设备在其他小鼠中的应用因高发病率和高死亡率而受到限制。此外，由于该设备是为在肾动脉水平植入腹主动脉而开发的，因此在肾下血流至关重要的研究中，如在怀孕小鼠中，其应用并不可行。我们详细介绍了一种在小鼠中植入无线电遥测设备的非常成功的替代方法，即将压力传感导管植入胸主动脉，并将发射器主体沿右侧腹皮下放置。我们使用雌性C57/BL6（C57）或BPH/5小鼠，BPH/5小鼠是由近交高血压和低血压小鼠品系杂交产生的品系。我们表明，对于平均体重22 g但小至17 g的小鼠，这是一种可靠的方法，可提供50 - 60天的高保真平均动脉压（MAP）和心率（HR）记录。使用该方法在这两个品系中均未观察到发病率或死亡率。重要的是，在手术后5 - 7天之前，这两个品系均未从麻醉和手术中完全恢复，正常昼夜节律的恢复表明了这一点。这也反映在恢复期间这两个品系的基线MAP和HR水平显著升高。此外，恢复的前5天MAP相对增加的品系相关差异掩盖了在完全恢复的小鼠中观察到的BPH/5基线MAP（与C57相比）的显著升高。这表明，方法必须允许至少5 - 7天的手术恢复期，以在小鼠中提供准确的心血管（CV）表型分析。最后，我们表明，使用这种替代植入方法，可以在小鼠怀孕前、怀孕中和产后连续监测CV参数。该设备不会干扰受孕、妊娠、分娩或幼崽的产后护理。这些结果证明了在典型体型的怀孕或未怀孕小鼠中进行无应激、长期监测CV参数的可行性，并为在CV功能基因组研究中的应用提供了令人兴奋的可能性。
