Abstract
We have recently established a method to measure renal (RSNA) and lumber (LSNA) sympathetic nerve activities simultaneously and continuously in freely moving rats and examined whether patterning of sympathetic outflow occurs in regionally different manner during changes in natural behavioural activities in rats. We observed a regional diversity of the sympathetic outflow during rapid eye movement (REM) sleep. RSNA decreased in a step manner during REM sleep that was accompanied by a step increase in LSNA. This indicates that the sympathetic regulation did not consist of a simple unidirectional readjustment, and sympatho-inhibition on the kidney coexists with the sympatho-excitation on the muscle during REM sleep in rats. This is consistent with the fact that renal blood flow and vascular conductance were increased while iliac blood flow and vascular conductance decreased during REM sleep. During non-REM sleep, quiet awake, moving and grooming states, LSNA and RSNA increased in parallel manner in proportion to the increase in physical activity. Systemic arterial pressure and heart rate increased associated with the increase in physical activity. The parallel increases in LSNA and RSNA seems favorable to the concomitant increases in systemic arterial pressure and heart rate. Together the data during REM sleep and other behavioural states, it would be seen that each behavioural state may generate a different pattern of the changes in RSNA and LSNA, which may be involved in state-related changes in cardiovascular functions during natural behavioural change in rats. [Jpn J Physiol 55 Suppl:S61 (2005)]
