Subnuclear organization of the lateral tegmental field of the rat. II: Catecholamine neurons and ventral respiratory group.

Bulbospinal and propriobulbar respiratory neurons of the ventral respiratory group and catecholamine neurons of the A1 and C1 cell groups were simultaneously labelled in the rat medulla by a combination of retrograde tracing and immunohistochemical identification. The ventral respiratory group and catecholamine cell groups form adjacent, parallel cell columns in the lateral tegmental field of the ventrolateral medulla. The ventral respiratory group is located immediately dorsal to the A1 and C1 groups, although some A1 neurons are intermingled with neurons of the rostral ventral respiratory group, and some C1 neurons are intermingled with those of the Bötzinger complex. The proximate populations of respiratory, catecholamine, and (presumptive) cardiovascular neurons identified in this study provide further support to the hypothesis that this region of the lateral tegmental field of the ventrolateral medulla is a site of cardiorespiratory coordination.