ISSN:
1432-2013
Keywords:
Sympathetic Reflexes
;
Cervical Sympathetic Trunk
;
Preganglionic Reflexes
;
Afferent Fibers
;
Cats
;
Sympathische Reflexe
;
Halssympathicus
;
Präganglionäre Reflexe
;
Afferente Fasern
;
Katzen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. The characteristics of the mass reflex response recorded monophasically from the cervical sympathetic trunk upon somatic nerve stimulation were studied in cats anesthetized with urethane and/or chloralose. The vagus and carotid sinus nerves of the animals were cut. 2. A single peripheral stimulus evoked a mass discharge with three initial negative deflections (components) having latencies of about 40, 70 and 110 ms respectively. Occasionally a small forth component with a latency of 280 ms was seen. Thereafter the potential became more positive than the control value. The negative deflections were the result of evoked spike discharges in the trunk fibers, whereas the positive deflection was due to the inhibition of the spontaneous spike activity (post-excitatory-depression, silent period). 3. There was a considerable variability of the amplitudes and latencies of the different components both in a succession of trials in the same animal and in different animals, but through the use of averaging techniques it was shown that the basic pattern was always preserved. No relation was found between the variability of sympathetic and of somatic reflexes evoked by the same afferent input. The variability of the sympathetic reflexes was not locked to the cardiac or to the respiratory cycle. 4. Volleys in low threshold cutaneous fibers (Group II fibers) were by far the most powerful afferents in evoking sympathetic reflexes. If cutaneous Group III fibers were included in the volley there was a further increase in reflex size. Activation of Group I afferents from muscle never produced sympathetic reflexes, but Group II and III afferents were quite effective. 5. The reflexes were followed by a silent period (post-excitatory-depression) during which the spontaneous discharge and the reflex effects of afferent volleys were suppressed. The time course of this silent period was investigated for a variety of conditioning-testing situations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00592245
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