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Experiments were performed in unanaesthetized rabbits and rats to investigate the distribution, within the medulla oblongata, of neurons activated during the Bezold-Jarisch reflex. Repeated intravenous injections of phenylbiguanide evoked depressor and bradycardic responses in both rabbits and rats. Fos-positive neurons were present in the nucleus tractus(More)
Extracellular recordings were made from 127 neurons, identified by antidromic activation from the supraoptic nucleus, in the A1 area of urethan-anesthetized rabbits. The median axonal conduction velocity was 0.7 m/s, and the median discharge rate was 3.9 spikes/s. Raising arterial pressure decreased the discharge rate in 94 of 101 neurons tested. Lowering(More)
Vagal afferents originating in abdominal viscera initiate numerous centrally-mediated responses, including behavioural, cardiovascular and hormonal changes associated with satiety, and nausea and vomiting. The present work was undertaken to map the pontomedullary distribution of neurons expressing Fos immunoreactivity following unilateral electrical(More)
We made extracellular recordings from 104 spinally projecting neurons in the rostral ventrolateral medulla of urethan-anesthetized rabbits to test whether inhibitory vasomotor neurons in the caudal ventrolateral medulla act by inhibiting rostral sympathoexcitatory neurons. The median conduction velocity was 8.3 m/s, and the median discharge rate was 2.9(More)
We made extracellular recordings from 107 spontaneously active neurons in the caudal ventrolateral medulla, after identifying the cells by antidromically activating them from the rostral ventrolateral medulla, in urethane-anesthetized rabbits. We tested the response of these neurons to inputs from baroreceptors and chemoreceptors. The median conduction(More)
We used extracellular recordings to examine the central pathway whereby electrical stimulation of abdominal vagal afferents elevates arterial pressure in the rabbit. Bulbospinal neurons in the rostral ventrolateral medulla were identified by antidromic activation from the dorsolateral funiculus of the thoracic spinal cord. Their barosensitivity was assessed(More)
In rats, secretion of vasopressin initiated by hemorrhage was completely abolished after muscimol-induced inhibition of neuronal function in the A1 region of the ventrolateral medulla oblongata. The A1 neurons are essential links in the central pathway to hypothalamic vasopressin-synthesizing neurons in this species.
We describe an intramedullary nitric oxide synthase (NOS) neural pathway that projects from the nucleus tractus solitarius (NTS) to the rostral nucleus ambiguus (NA) in the rabbit. With the use of NADPH diaphorase histochemistry and NOS immunohistochemistry, a compact group of NOS-positive perikarya was identified in the central subnucleus of the NTS(More)
The medulla oblongata was examined with Fos and tyrosine hydroxylase (TH) immunohistochemistry after 2 h of intermittent nasopharyngeal stimulation with formaldehyde vapour in the conscious rabbit. The stimulation caused apnoea, bradycardia and a rise in blood pressure known to be associated with vigorous vasoconstriction. Fos-positive neurons occurred in(More)