Beat-to-beat fluctuations in the BP related signals in rats: can it contribute to the understanding of the development of hypertension?

Abstract The goal of this study was to investigate the alterations in blood pressure control in young spontaneously hypertensive rats (SHR), as reflected in the power distribution of blood pressure fluctuations. We studied six SHR preceding the onset of overt hypertension, compared to six age matched control rats, the normotensive Wistar–Kyoto rats (WKY), and analyzed the power density distribution of several blood pressure related signals, namely: arterial blood pressure (ABP), systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) and heart rate (HR). ABP fluctuations exhibited a basic difference in the power distribution pattern between the strains: at low frequencies ( α 1 sympathetic blockade. This study supports previous findings in which differences in cardiovascular control occur in SHR already at the prehypertensive stage. The above results suggest that α 1 sympathetic control is altered in the SHR strain, and therefore, when this limb is blocked, some of the differences between the strains disappear. Furthermore, the analysis of the BP related signals enable us to identify alterations existing in the control mechanisms in SHR, which involve adjunct control mechanisms enhanced under α 1 sympathetic blockade. Finally, an important result is, that for all BP related signals under study, excluding HR, the response to α 1 -blockade reduces the power density in the 0.07–0.15 Hz region indicating that this region is directly associated with the activity of α control.