Action of externally applied ATP on rat reticulospinal vasomotor neurons.

In anesthetized rats, iontophoretic application of ATP excited the spinal cord-projection neurons in the rostral ventrolateral reticular nucleus of the medulla oblongata. The neuronal response to ATP was mimicked and then blocked by alpha,beta-methylene-ATP, a metabolically stable ATP analogue, and the response was abolished by suramin. Microinjections of ATP (3-100 pmol) into the rostral ventrolateral medulla produced a powerful pressor response. The results suggest that ATP may function as a neurotransmitter or neuromodulator involved in medullary regulation of cardiovascular functions.