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

P>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 (SS) rats are genetically susceptible to salt-sensitive hypertension, the development of which depends on diet. Substitution of chromosome 13 of SS rats with that of Brown Norway rats confers salt-resistance to consomic SS-13BN rats. 3. In the present study, we tested whether differences in the central and baroreflex contributions to HP control occur among wake-sleep states in SS and SS-13BN rats and reflect genetic susceptibility to hypertension. Rats (n = 5 per group) were fed a prohypertensive diet late during development to minimize hypertension in SS rats and were 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 rats, 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 rats in any wake-sleep state. 5. The 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 generalized to other rat models used in hypertension research. Impairments in the baroreflex and central autonomic control of HP during quiet wakefulness and REMS, respectively, cannot be generalized as an index of genetic susceptibility to hypertension.