Chronic carbon monoxide poisoning: effects on performance of the isolated right ventricle.

Rats were exposed continuously for 21-35 days to 500 ppm carbon monoxide (37.4-39.2% HbCO). Aerobic resting force (RF)-active isometric twitch force (AF) curves of isolated right ventricle preparations were constructed at 27 degrees C. CO and control groups are nearly identical when expressed as percent of maximal AF over the range of RF used. There are no significant differences in AF either at the peak of the curve or at RF = 1 g. During 15 min of anoxia AF declines at both RF's used. Increased anoxic tolerance is apparent in all CO preparations when anoxic AF is plotted as percent of preanoxic AF. The effect is most marked at RF = 1 g, where time to one-half preanoxic AF is 12.6 +/- 0.9 vs.9.3 +/- 0.8 min for CO-exposed and controls, respectively. However, no significant differences in "absolute" AF are seen between the groups at either level of RF at any minute during anoxia. Aerobic recovery of CO preparations is markedly enhanced at 1 g RF. Anoxic tolerance and aerobic recovery differences, however, are smaller at the peak of the RF-AF curve. Effects on time to peak AF and maximal rate of rise of AF are not marked at either level of RF in CO preparations.