Central and baroreflex control of heart period during the wake-sleep cycle in consomic rats with different genetic susceptibility to hypertension.

1. In Spontaneously Hypertensive Rats (SHR), the contributions of the baroreflex and central autonomic commands to the control of heart period (HP) vary among wake-sleep states and are impaired during quiet wakefulness and rapid-eye-movement sleep (REMS), respectively. 2. Dahl salt-sensitive rats (SS) are genetically susceptible to salt-sensitive hypertension, the development of which depends on diet. Substitution of chromosome 13 of SS with that of Brown Norway rats confers salt-resistance to consomic SS-13BN rats. 3. We tested whether differences in the central and baroreflex contributions to HP control occur among wake-sleep states in SS and SS-13BN and reflect genetic susceptibility to hypertension. Rats (n = 5 per group) were fed a pro-hypertensive diet late during development to minimise hypertension in SS and instrumented with an arterial catheter and electrodes for discriminating wake-sleep states. 4. The cross-correlation function between HP and blood pressure indicated that in SS and SS-13BN, the contributions of the baroreflex and central commands to the control of HP differed significantly among wake-sleep states, with central commands outweighing the baroreflex in REMS. However, these contributions did not differ significantly between SS and SS-13BN in any wake-sleep state. 5. Data suggest that differences in the central and baroreflex contributions to HP control among wake-sleep states, which have been demonstrated in SHR, can be generalised to other rat models employed in hypertension research. Impairments in the baroreflex and central autonomic control of HP during quiet wakefulness and REMS, respectively, cannot be generalised as an index of genetic susceptibility to hypertension