Skeletal Muscle Reflexes of Splanchnic and Intercostal Nerve Origin in Acute Spinal and Decerebrate Cats

Downman, C. B. B.

doi:10.1152/jn.1955.18.3.217

Cited by 110 publications

(47 citation statements)

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“…Thus ANOVA showed a statistically significant effect of dose on the size of the early VS reflex, but no effect of stimulus number. (Downman, 1955) and rabbit (Alderson & Downman, 1960). In spinalized animals, stimulation of the splanchnic nerve evokes reflex volleys in all the body wall nerves, with the largest responses being obtained from the lower thoracic and upper lumbar nerves (Downman, 1955 immediately adjacent nerves and decrease in size progressively above and below this point (Downman, 1955).…”

Section: Somato-somaticmentioning

confidence: 98%

Excitability changes of somatic and viscero‐somatic nociceptive reflexes in the decerebrate‐spinal rabbit: role of NMDA receptors.

Laird

Rubia

Cerveró

1995

The Journal of Physiology

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Section: Somato-somaticmentioning

confidence: 98%

Excitability changes of somatic and viscero‐somatic nociceptive reflexes in the decerebrate‐spinal rabbit: role of NMDA receptors.

Laird

Rubia

Cerveró

1995

The Journal of Physiology

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“…The thoracic dorsal roots contain afferents that excite motoneurones monosynaptically in the same and adjacent segments (Sears, 1964b;Kirkwood & Sears, 1982 a, b) and polysynaptically with a wider distribution (Downman, 1955;Aminoff & Sears, 1971 However, our principal evidence concerning the influence of dorsal root afferents is that many of the experiments described above were performed with the ipsilateral dorsal roots cut in up to five segments, always including the ones used for efferent recordings a, b; Kirkwood et al 1981b). An approximately equal number of the experiments were performed with the roots intact.…”

Section: Effects Of Dorsal Root Sectionmentioning

confidence: 99%

“…Removing a large part of this input reduces the 'dilution' or other effects already described but, since threshold for the motoneurones that contribute to the histogram was still achieved, albeit at an elevated level of C02, then it is likely that this respiratory input had been replaced by some other excitatory input. We presume that this other input was provided by spinal cord interneurones released from descending controls (Downman, 1955;cf. Sherrington & Sowton, 1915;Eccles & Lundberg, 1959), but we do not know whether these interneurones have respiratory patterns of activity or not.…”

mentioning

confidence: 95%

Variations in the time course of the synchronization of intercostal motoneurones in the cat

Kirkwood

Sears

Tuck

et al. 1982

The Journal of Physiology

139

117

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SUMMARY1. Synchronization of intercostal motoneurones was studied by the construction of cross-correlation histograms which related the firing times of paired groups of efferent inspiratory or expiratory discharges recorded from filaments of the external or internal nerves of anaesthetized or decerebrate cats.2. The principal feature of the histograms was always a central peak but the time course of the central peak showed considerable variation. Three forms of synchronization were defined on the basis of the time course of the central peak: (i) short-term synchronization (Sears & Stagg, 1976), where the peak was narrow, extending over about + 3 ms but sometimes with weak shoulders to about + 5 ms; (ii) broad-peak synchronization where the peak was wider than this (often + 20 ms or more) but where there were no strong periodicities; (iii) high-frequency oscillation (h.f.o.) synchronization, which was named from the related phenomena in medullary and phrenic recordings (Cohen, 1979), where there were periodic peaks on either side of the central peak with a frequency in the range 60-120 Hz. Combinations of these forms of synchronization were seen in some histograms.3. When different animals were compared, broad peak synchronization was seen in association with light anaesthesia and with polysynaptic excitation of the motoneurones from muscle spindle afferents. 4. In individual animals, additional anaesthesia depressed both broad peak and h.f.o. synchronization.5. Raising PA, co2, which increased the respiratory drive to the motoneurones, favoured short-term or h.f.o. synchronization at the expense of broad-peak synchronization.6. In three decerebrate animals only short-term or h.f.o. synchronization was seen. 7. Spinal cord lesions above or below the segments ofinterest promoted broad-peak synchronization, even with high PA, co, or deep anaesthesia.8. We conclude: (i) that short-term synchronization, due mainly to the branching of presynaptic axons, is generated mainly by those axons which transmit the respiratory drive, that drive providing most of the excitation of the motoneurones

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“…For phrenic nerve recording, the changes in amplitude and duration of the phrenic discharge were assessed once per cycle to determine their maximal variations. For the majority of mechanical and chemical tests, the depression of phrenic activity remained stable for a few breaths (5)(6)(7)(8)(9)(10)(11)(12). Thus reported data corresponded to the averaged changes in amplitude and duration of phrenic discharge.…”

Section: Discussionmentioning

confidence: 77%

“…The existence of direct connections between parietal pleural afferents in internal intercostal nerves and phrenic motoneurons is similar to an inhibitory visceromotor reflex similar to that reported between the splanchnic afferents and the diaphragm (1, 2, 12). As for the pleural-to-phrenic reflex here described, splanchnic-to-phrenic reflex involves the activation of nonmyelinated afferent fibers (2) directly connected with ipsilateral phrenic motoneurons because the reflex persists in animals spinalized between C1 and C2 (1,12). The splanchnic-to-phrenic reflex may explain inhibition of diaphragm electromyogram after peritoneal effraction with laparotomy (4) or simple laparoscopy (34).…”

Section: Discussionmentioning

confidence: 98%

Respiratory and circulatory effects of parietal pleural afferent stimulation in rabbits

Jammes

Delpierre²

2006

Journal of Applied Physiology

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Jammes, Yves, and Stéphane Delpierre. Respiratory and circulatory effects of parietal pleural afferent stimulation in rabbits. J Appl Physiol 100: 1539 -1546, 2006; doi:10.1152/japplphysiol.01422.2005. -Respiratory symptoms accompanying pleural diseases combine dyspnea, tachypnea, rapid shallow breathing, and sometimes hypotension. There are no experimental data on the changes in respiratory and circulatory functions elicited by the activation of pleural afferents. After removal of all muscles covering the 5th to 10th intercostal spaces, we investigated in paralyzed, vagotomized rabbits the changes in phrenic discharge, transpulmonary pressure, and systemic arterial pressure in response to an outwardly directed force exerted on the parietal pleura or the local application of solutions containing lactic acid or inflammatory mediators. Mechanical stimulation of the pleura induced an immediate decrease in both integrated phrenic discharge and arterial blood pressure, the responses being positively correlated with the magnitude of force applied on the pleura. No accompanying changes in ventilatory timing, transpulmonary pressure, or heart rate were measured. Lactic acid solution also elicited an inhibition of phrenic activity and a fall in blood pressure. Section of the internal intercostal nerves supplying the stimulated intercostal spaces totally abolished the responses to mechanical stimulation or lactic acid. An inflammatory mixture elicited only modest respiratory and circulatory effects. We concluded that an acute mechanical distension of the parietal pleura as well as its chemical stimulation by lactic acid elicit a marked inhibition of phrenic motoneurons combined to a reduction of the sympathetic outflow to the circulatory system. pleura; sensory innervation; phrenic activity; circulatory control IN A PREVIOUS STUDY IN RABBITS, we identified afferents in internal intercostal nerves that were activated by mechanical and/or chemical stimulation of the thoracic pleura (19). The nerve responses were attributed to the selective activation of pleural afferents because they existed after complete removal of all muscles covering the studied intercostal spaces. Because the conduction velocity of these afferents ranged between 0.5 and 14 m/s, we deduced that they belonged to the group III (thin myelinated) and IV (unmyelinated) fibers. Most units (97%) were activated by mechanical stimulation of the pleura (local positive pressure range ϭ 4.5 to 8.5 cmH 2 O), and we found a linear relationship between the discharge rate of afferents and the force applied to the thoracic wall. However, only 29% of this nerve population was purely mechanosensitive. The other units also responded to lactic acid and/or inflammatory mediators and were considered multimodal receptors. The response to lactic acid was roughly proportional to its concentration.Pleural diseases cause pain, dyspnea, tachypnea, and rapid shallow breathing, and sometimes hypotension, which only occurs under specific circumstances, e.g., tension pneumothorax, over...

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Skeletal Muscle Reflexes of Splanchnic and Intercostal Nerve Origin in Acute Spinal and Decerebrate Cats

Cited by 110 publications

References 0 publications

Excitability changes of somatic and viscero‐somatic nociceptive reflexes in the decerebrate‐spinal rabbit: role of NMDA receptors.

Excitability changes of somatic and viscero‐somatic nociceptive reflexes in the decerebrate‐spinal rabbit: role of NMDA receptors.

Variations in the time course of the synchronization of intercostal motoneurones in the cat

Respiratory and circulatory effects of parietal pleural afferent stimulation in rabbits

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