Circadian murine ouabain chronotolerance revisited.

Data published earlier on a possible circadian variation in murine susceptibility to intravenously-administered ouabain and analyzed by conventional biometric methods, were reanalyzed by cosinor procedures. A statistically significant circadian rhythm could thus be demonstrated, contradicting the earlier conclusion that there was no circadian rhythm in susceptibility to ouabain when injected intravenously. Results from this reanalysis agreed with those from previous investigations in which ouabain was injected intraperitoneally or subcutaneously. Thus, a circadian rhythm characterizes murine susceptibility to ouabain given via 3 different routes.