• Harumi Nakayama, Hiroshi Takahashi, Naomitsu Okubo, Masayuki Miyabe, and Hidenori Toyooka.
• Department of Anesthesia, Ushiku Aiwa General Hospital, Ibaraki, Japan. hami@sky.zero.ad.jp
• Can J Anaesth. 2002 Apr 1; 49 (4): 375-9.

PurposeTo examine the inotropic and chronotropic effects of xenon (Xe) and nitrous oxide (N2O) compared with nitrogen (N2) on isolated rat hearts. The differences between Xe and N2O were also compared.MethodsThe effects of Xe, N2O and N2 on coronary perfusion pressure (CPP), heart rate, left ventricular developed pressure (LVDP) and double product (DP) were examined in isolated rat hearts perfused at constant flow (10 mL x min(-1)). Following stabilization and baseline measurement with 95% O2 (plus 5% CO2), the heart was exposed to buffer equilibrated with one of three test gases; 50% N2 with 45% O2 (Group N2: n=9), 50% Xe with 45% O2 (Group Xe: n=9), or 50% N2O with 45% O2 (Group N2O: n=9) for 30 min. Measurements were performed in the last minute of exposure to the test gases.ResultsGas exposure in all three groups decreased O2 delivery (-50%), CPP (-11%), LVDP (-30%) and DP (-44%) compared with baseline values (P <0.001). However, there were no differences among the groups.ConclusionOur data suggest that cardiac contractility was decreased by the effects of reduced O2 delivery, but both Xe and N2O did not cause further cardiac depressant effects compared to N2 in this experimental model.

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