Measurement of Cardiovascular Response in Male Sprague-Dawley Rats Using Radiotelemetric Implants and Tailcuff Sphygmomanometry: A Comparative Study

Abstract

Long-term cardiovascular studies with conscious animals have typically been accomplished in one of three ways: (1) by direct cannulation of an artery and tethering to an exogenous transducer and recorder, (2) by indirect monitoring via noninvasive tailcuff sphygmomanometry (tailcuff), and (3) by use of radiotelemetric implantable transmitters (implants). Direct cannulation with tethering is technically demanding, stressful to animals, and suffers from loss of patency of the artery over time; therefore, it was excluded from a comparison of these procedures. Tailcuff has the intrinsic advantage of being noninvasive. However, tailcuff requires at least several days (or more) of animal training to eliminate pulse artifacts generated by stress or gross body movements from close containment within unfamiliar surroundings. No training is involved with implantation. Although several days are needed to insure recovery of the animal from surgery, no long-term, overt physiological stress was detected in animals subjected to implantation in terms of weight gain, liver to whole-body ratios, gross changes in liver histology, or changes in blood pressure or heart rate (as measured by tailcuff). With one exception, correlations of tailcuff readings to each other were substantially lower than correlations of implant readings to each other, indicating that the implant readings were more internally consistent. Correlations of blood pressure and heart rate parameters between tailcuff and implant measurements were either modest or not significant. The implantation method has one important advantage over tailcuff: Animals can be monitored continuously day and night without the need for interfering with animal activity.