Rhythmic activities of the sympatho-excitatory neurons in the medulla of rabbits: neurons controlling cutaneous vasomotion.
Spontaneous activities of the reticulospinal neurons in the reticular formation of the rostroventral medulla, of the ear sympathetic nerve (ESNA) and of the renal sympathetic nerve (RSNA) were analyzed with regard to cardiac cycle- and respiration-related rhythm in the anesthetized, vagotomized and immobilized rabbits. A reticulospinal neuron that was concurrently excited with increase in the ESNA and/or reduction of the blood flow of the ear skin by electrical stimulation of the dorsomedial hypothalamus was tentatively named as a cutaneous sympatho-excitatory neuron (Cu neuron). More than half of the Cu neurons (13/22) had a respiration-related rhythmic activity as well as the ESNA. Activity of most of the Cu neurons (19/22) was not modulated with the frequency of the heartbeat and the ESNA had little or no cardiac cycle-related activity. Simultaneous recording shows that the degree of modulation (relative power of the power spectrum of the post event time histogram at the frequency of the respiration) of activity of the Cu neurons correlated with that of the ESNA. On the other hand, most (13/18) of the barosensitive sympatho-excitatory reticulospinal neurons in the rostral ventrolateral medulla (RVLM neurons) had both cardiac cycle- and respiration-related activity as well as the RSNA had. The Cu neurons were located at the medial sites to the location of the RVLM neurons. These results further showed that the Cu neurons controlled the cutaneous vasoconstrictor fibers and that the sympatho-excitatory neurons were located at the different sites in the ventral medulla according to their function.
Ootsuka
Youichirou
Y
Institute of Basic Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan.
Rong
Weifang
W
Kishi
Erika
E
Koganezawa
Tadachika
T
Terui
Naohito
N
D000320:Adrenergic Fibers / Q000502:physiology; D000818:Animals; D017763:Autonomic Denervation; D001794:Blood Pressure / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D004423:Ear / Q000098:blood supply / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology; D007033:Hypothalamus, Middle / Q000502:physiology; D007668:Kidney / Q000294:innervation / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011311:Pressoreceptors; D011817:Rabbits; D012039:Regional Blood Flow / Q000502:physiology; D012143:Respiratory Physiological Phenomena; D013116:Spinal Cord / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*