Central neurotransmitters in cardiorespiratory control mechanisms

The results of the studies discussed demonstrate that central cardiovascular pathways rely on excitatory and inhibitory amino acids for rapid transmission of information. This rapid neurotransmission can be modulated by the action of amines, indoleamines and peptides that are co-stored, and presumably co-released, from the terminals of medullary cardiovascular neurons. Combined analysis of different patterns of activity, responses to stimulation of afferent pathways, antigen content and receptor expression, suggest that bulbospinal barosensitive neurons, that are likely to be sympathoexcitatory, receive glutamatergic and GABAergic inputs acting via multiple receptor subtypes. These bulbospinal neurons express a range or receptors on their somata, contain many combinations of neurotransmitters, and have many different patterns of respiratory-related activity. The challenge in the future is to discriminate functionally separate pathways on the basis of this knowledge. Such a segregation would yield much new information and have important therapeutic implications in the management of essential hypertension.