Journal of the autonomic nervous system
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J. Auton. Nerv. Syst. · Sep 1984
Comparative StudyComparison of the distributions of renal and splenic neurons in sympathetic ganglia.
Postganglionic neurons in different sympathetic ganglia are innervated selectively by preganglionic neurons originating from different segments of the spinal cord. These selective connections between pre- and postganglionic neurons may determine the specificity with which postganglionic nerves participate in differential reflex reactions. Because specificity of renal and splenic nerve responses to stimulation of visceral afferent nerves may depend on the distribution of postganglionic neurons in sympathetic ganglia, retrograde axonal transport of horseradish peroxidase was employed in this study to identify the ganglionic distribution of cell bodies of postganglionic neurons supplying the kidney and spleen in cats. ⋯ Most labeled cell bodies of renal nerves were clustered in groups within the solar plexus, but some cell bodies of renal neurons were observed in upper lumbar (L1-L3) and lower thoracic (T12-T13) paravertebral sympathetic ganglia. In contrast, 90% of labeled splenic neurons were scattered randomly throughout the left and right celiac poles of the solar plexus. In conclusion, the disparate distribution of renal and splenic neurons in sympathetic ganglia provides an anatomical basis for differential reflex responses in the two populations of nerves.
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J. Auton. Nerv. Syst. · Mar 1983
Changes of reflexes in vasoconstrictor neurons supplying the cat hindlimb following chronic nerve lesions: a model for studying mechanisms of reflex sympathetic dystrophy?
The generic term 'reflex sympathetic dystrophy' describes a clinical syndrome which sometimes develops after traumata at the extremities with lesions of nerves or --more rarely--after other events. The syndrome consists of the following components: pain (hyperpathia, allodynia), trophic changes of skin and deep tissues, dysregulation of sweating and cutaneous blood flow of the extremity concerned. It is assumed that all symptoms are produced by abnormal sympathetic activity. ⋯ The results obtained show that the reciprocity of the reflex pattern which is normally observed between cutaneous and muscle vasoconstrictor neurons is lost in many animals. Cutaneous vasoconstrictor neurons are very similar to muscle vasoconstrictor neurons in their reactions to stimulation of arterial baroreceptors and chemoreceptors. If the same sequence of events also occurs in patients with reflex sympathetic dystrophy, it could explain the dysregulation of blood flow through skin and also the occurrence of trophic changes in the limb.
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J. Auton. Nerv. Syst. · May 1982
Effect of ketamine, althesin, and thiopentone on the Valsalva-constrictor and heart rate reflexes of the rabbit.
The circulatory effects of Valsalva-like manoeuvers were studied before and during i.v. infusions of either ketamine, Althesin and thiopentone given in doses that produced similar levels of light anesthesia. The Valsalva-like manoeuvers were of 30 s duration and consisted of applying Valsalva pressures (VP) from 2.5 to 20 mm Hg to the animal's respiratory valve and to a cuff placed around its thorax and abdomen. ⋯ Ketamine and thiopentone produced marked depression of the Valsalva-heart rate reflex, but Althesin had relatively little effect. We concluded that ketamine produces greater impairment of blood pressure homeostasis mediated through constrictor and heart rate reflexes evoked through arterial and cardiopulmonary baroreceptors than the other two anesthetics.
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J. Auton. Nerv. Syst. · Mar 1982
Effects of ketamine and Althesin Anesthesia on baroreceptor--heart rate reflex and hemodynamics of intact and pontine rabbits.
The changes in baroreceptor-heart rate reflex properties and in hemodynamics produced by light ketamine anesthesia were studied in one group of rabbits before and after infracollicular decerebration and those produced by althesin anesthesia in another group. Ketamine produced marked depression of baroreceptor reflex-mediated vagal effects on heart rate which was of similar magnitude in intact and pontine decerebrate rabbits; this indicates that its action was largely at or below the pons. ⋯ In the intact rabbit ketamine produced a greater rise in blood pressure than Althesin anesthesia for 1 h; the greater pressor response was due to a transient rise in total peripheral resistance (TPR) and a sustained rise in cardiac output. The difference in the blood pressure responses was mainly due to differences in action of the two anesthetics at or below the pons and only the transient rise in TPR during ketamine anesthesia was mediated through a suprapontine pathway.
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J. Auton. Nerv. Syst. · Apr 1981
Organization of the sacral parasympathetic reflex pathways to the urinary bladder and large intestine.
Electrophysiological and horseradish peroxidase (HRP) techniques have provided new insights into the organization of the sacral parasympathetic reflex pathways to the large intestine and urinary bladder. The innervation of the two organs arises from separate groups of sacral preganglionic cells: (1) a dorsal band of cells in laminae V and VI providing an input to the intestine; and (2) a lateral band of cells in lamina VII providing an input to the bladder. These two groups of cells were separated by an interband region containing tract cells and interneurons. ⋯ The long latency is attributable to the slow conduction velocity in immature unmyelinated peripheral and central axons. In chronic spinal kittens (3-7 days after spinalization) the long latency reflex was abolished and a shorter latency (90-150 msec) bladder reflex was unmasked. The emergence of this spinal pathway may reflect axonal sprouting and the formation of new reflex connections within the sacral parasympathetic nucleus.