Figure 2. Spontaneous baroreflex sensitivity in wild-type (WT) and Cry1^−/−Cry2^−/− mice.

The slope (ΔHR/ΔMAP), the spontaneous baroreflex sensitivity, was determined from regression analyses (Brace, 1977) on data during periods where ΔMAP was negatively correlated with ΔHR (P < 0.05). The number of data was ∼83 000 in each graph. Note that ΔHR/ΔMAP is enhanced during the night in a WT mouse while the diurnal difference disappeared in a Cry1^−/−Cry2^−/− mouse with enhanced ΔHR/ΔMAP.