MEASUREMENT OF HEART-RATE AND Q-T INTERVAL IN THE CONSCIOUS MOUSE

Transgenic mouse models provided a powerful tool to evaluate the physi ological significance of altered quantities or characteristics of spec ific gene products, such as cardiac ion channels. We have developed a system to record and analyze changes in the electrocardiogram in the m ouse using an implantable telemetry system. The R-R and Q-T intervals were measured on individual beats and on signal-averaged complexes der ived from 1, 2, or 4 s of contiguous data each hour during a 24-h peri od in three male and three female FVB mice. Duration of averaging had minimal effect on the measured Q-T. The Q-T interval was shown to be r elated to the square root of the R-R interval, and an appropriate form ula for a rate-corrected Q-T interval (Q-T-c) was derived. Ketamine an esthesia was shown to markedly increase duration and variability in R- R, Q-T, and Q-T-c intervals. In conscious animals, variability in Q-T was low across animals and over time, suggesting that this should be a sensitive model for detection of changes in the Q-T interval in trans genic mice with ion channel defects.