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DIFFERENTIAL AUTONOMIC CONTROL OF REGIONAL CIRCULATORY REFLEXES EVOKED BY THERMAL STIMULATION AND BY HYPOXIA
Author(s) -
Iriki M,
Simon E
Publication year - 1973
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1973.28
Subject(s) - vasomotor , stimulation , hypoxia (environmental) , efferent , reflex , autonomic nervous system , sympathetic nervous system , sympathetic activity , medicine , blood pressure , heart rate , afferent , chemistry , organic chemistry , oxygen
Summary In anaesthetized, paralyzed, artificially ventilated rabbits the discharges of sympathetic efferent nerves confined to the ear skin, to the intestine and to the heart were recorded together with ear skin temperatures and arterial pressure. The regional sympathetic responses to adequate stimulation of temperature sensors of thermoregulatory importance (in the skin, the hypothalamus and the spinal cord) were studied and were compared with the vasomotor reactions elicited by changes of blood gas composition. The results have presented direct evidence for the hypothesis that situations of generalized stress, such as thermal imbalance and arterial hypoxia, may induce a differentiation of regional sympathetic output up to the degree of regionally opposite changes of activity, i.e. of “qualitative differentiation” within the sympathetic nervous system. The patterns of vasomotor differentiation which were evoked by thermal stimulation of each of the investigated thermosensitive areas were identical and are regarded as a specific thermoregulatory response which is produced by the hypothalamic centre of temperature regulation. This response was definitely different from the pattern of vasomotor differentiation evoked by arterial hypoxia or by hyper‐capnia with respect to the responses of the cardiac sympathetic efferents. It is concluded that the phenomenon of qualitative sympathetic differentiation is not the result of a fixed autonomic reaction. Instead, the different patterns observed under different conditions are regarded as specific autonomic regulatory responses which are evoked in order to adjust cardiovascular performance according to the special demands which arise from the various types of generalized stress.