Supraventricular characteristics of the rat are markedly affected by commonly used general anesthetics relative to the freely moving state
2Regenerative Medicine & Stem Cell Research Center, Ben-Gurion University of the Negev, Israel
Introduction: The utility of rodents in AF research is rapidly growing. However, due to technical challenges such studies are routinely conducted in the anesthetized state. Recently, we introduced an implantable system adapted for comprehensive atrial studies in ambulatory rats. Here, we systematically compared the supraventricular electrophysiology (EP) under commonly used anesthetics to the freely moving state.
Methods: Rats (n=8) were evaluated four weeks post implantation. EP studies were conducted under the freely moving state, 2% isoflurane (ISO), and under 40mg/kg pentobarbital (PEN). RR, PR, and QT intervals were analyzed conventionally. Stimulation protocols were conducted to determine AVERP and AERP under several basic cycle lengths (BCLs) and corrected sinus node recovery time (CSNRT).
Results: RR, PR and QT interval did not differ significantly between the different states. Pacing threshold decreased from 225.0±168.2 µA in awake state to 143.5±110.9 µA and 153.8±86.3 µA under ISO and PEN, respectively (p < 0.05). CSNRT increased from 16.44±5.3 ms in awake state to 25.4±4.0 ms under ISO (p < 0.05), but did not change significantly under PEN. AVERP at all BCLs increased ~5 ms under ISO and ~11 ms under PEN (p < 0.0001). AERP at all BCLs increased ~10ms under ISO and ~5ms under PEN compared to the awake state (p < 0.0001).
Conclusion: Our results demonstrate prominent impact of commonly used anesthetics on supraventricular EP. These findings should have critical implications on AF research in rodents. Our findings stress the importance of methodologies enabling rodent EP studies in the freely moving state.