Rostral ventrolateral medullary neurons projecting to locus coeruleus have cardiorespiratory inputs

Abstract

This study was designe to characterized some of the properties of the rostral ventrolateral medullary (RVLM) cells with axonal projection to the locus coeruleus (LC) in urethane anesthetized, vagotomized, paralyzed and artificially respirated rats. The vast majority of RVLM units antidromically (AD) activated from LC (RVLM-LC units) were silent and unresponsive to peripheral chemoreceptor stimulation or nociceptive stimulation. Twenty seven spontaneously active RVLM-LC neurons, AD activated from LC with currents below 30 μA (17 ± 2 μA) were analyzed. AD mapping (n = 18) indicated that the lowest threshold for AD activation occurred within the LC itself. Axonal branching within or close to LC..