Activity of neurons of the cerebral A5 zone of rat induced by adequate stimulation of muscle afferents: On the control of arterial pressure and respiration during muscle activity |
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Authors: | V F Pyatin V S Tatarnikov E N Glazkova |
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Institution: | (1) Samara State Medical University, Ministry of Public Health, Samara, Russia |
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Abstract: | In experiments on 24 anesthetized rats with preserved spontaneous respiration, we first recorded the volley impulse activity
of neurons (n = 30) in the brainstem A5 zone, which was induced by periodical stretchings of the forelimb flexors and hindlimb extensors.
The frequency of action potentials in such volleys was, on average, 99.7 ± 19.6 sec−1. In the course of this kinesthetic stimulation, along with the activation of “proprioceptive” neurons of the A5 zone, we
observed transitory drops in the arterial pressure and increases first recorded the activity of baroceptive neurons in subpial
parts of the A5 zone (n = 4); the frequency of their background impulsation was, on average, 25.1 ± 0.8 sec−1. This activity in all cases was transitorily suppressed both upon increases of the blood pressure caused by constriction
of the carotid arteries or nociceptive tail stimulation, as well as upon stretching of skeletal muscles. Therefore, we first
obtained direct proof that neuronal systems of the A5 zone are involved in integration of visceral and somatic proprioceptive
afferent influences. We hypothesize that the physiological role of this mechanism of integration of somatic and visceral information
at the level of the A5 zone is directed toward lowering of the arterial pressure and intensification of respiration within
the period of intensified motor activity. This mechanism is based on the interaction between “proprioceptive,” baroceptive,
and, perhaps, multiceptive neurons within the A5 zone.
Neirofiziologiya/Neurophysiology, Vol. 39, No. 6, pp. 443–452, November–December, 2007. |
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Keywords: | neurons of the A5 zone somatosensory inputs respiration arterial pressure |
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