Reflexes elicited by visceral stimulation in the acute spinal animal

Downman, C. B. B.; McSwiney, B. A.

doi:10.1113/jphysiol.1946.sp004155

Cited by 59 publications

(15 citation statements)

References 3 publications

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“…Exposed intestinal loops were kept warm and moist by surrounding them with pads of cotton-wool wrung out in warm saline, or by immersing the trunk of the animal in a bath of Locke solution at 38-39°C. A few tests were done on the intestines of decerebrated cats subjected to spinal cord transection between segments C 8 and T 1; the details of this procedure have been reported by Downman & McSwiney (1946). A detailed map of the loop of small intestine to be used was made by laying a sheet of thin celluloid over the spread-out loop and tracing on it in waterproof black ink an outline of the loop together with the course of the neurovascular bundles of the mesentery.…”

Section: Methodsmentioning

confidence: 99%

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Distribution along the small intestine of afferent, vasoconstrictor and inhibitory fibres in the mesenteric nerve bundles

Downman¹

1952

The Journal of Physiology

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In spite of failure to show pain sensibility of the small intestine at operation on man (Lennander, 1903), there is evidence that it is served by afferent nerve fibres. Activity of these fibres evokes widespread reflex actions, such as limb movements, blood-pressure changes and pupil dilatation in cats (Downman & McSwiney, 1946;Downman, McSwiney & Vass, 1948). The latter authors showed that a variety of stimuli-mechanical, chemical and thermal-are effective when applied to the outer (serous) surface of the small intestine. By shielding the mesentery from the action of the stimulating agent it was shown that the intestine itself is sensitive, independent of its mesentery. Sjostrand & von Euler (1946) reached a similar conclusion. Having evidence that afferent fibres course in the intestine it is reasonable to attempt to determine the territory innervated by each bundle of such fibres which is grouped around the mesenteric artery. Such an attempt is reported below. During the necessary testing it was noted that the distribution of the vasoconstrictor and the inhibitory fibres, forming parts of the same mesenteric nerve bundles, could also be mapped. Nolf (1928) has produced evidence that the post-ganglionic sympathetic fibres, as they enter the wall of the intestine of the chicken, send long branches of some 41 cm. up and 8 cm. down the bowel, while preganglionic sympathetic and vagal fibres cover a length of more than 20 cm. of intestine. The findings in the present investigation do not conform with Nolf's conception of the distribution of efferent fibres. METHODSCats were anaesthetized with chloralose, 70-80 mg./kg. body weight, given intravenously during initial ether anaesthesia. They were left undisturbed until the pupil was slit-like. The belly was then opened by an incision in the flank, curving forwards and downwards from the kidney, or by a midline incision in the [inea alba. Exposed intestinal loops were kept warm and moist by surrounding them with pads of cotton-wool wrung out in warm saline, or by immersing the trunk of the animal in a bath of Locke solution at 38-39°C. A few tests were done on the intestines of decerebrated cats subjected to spinal cord transection between segments C 8 and T 1; the details of this procedure have been reported by Downman & McSwiney (1946). A detailed map

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Section: Methodsmentioning

confidence: 99%

“…Activity of these fibres evokes widespread reflex actions, such as limb movements, blood-pressure changes and pupil dilatation in cats (Downman & McSwiney, 1946;Downman, McSwiney & Vass, 1948). The latter authors showed that a variety of stimuli-mechanical, chemical and thermal-are effective when applied to the outer (serous) surface of the small intestine.…”

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Distribution along the small intestine of afferent, vasoconstrictor and inhibitory fibres in the mesenteric nerve bundles

Downman¹

1952

The Journal of Physiology

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“…Institute of Orthopaedics, Stanmore, Middlesex (Received 26 June 1959) Stimulation of visceral afferent nerve fibres evokes activity in skeletal muscles (Miller & Simpson, 1924;Mellanby & Pratt, 1940;Downman & McSwiney, 1946) and leads to alterations in somatic reflexes (Dusser de Barenne & Ward, 1937;Schweitzer & Wright, 1937).…”

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The effects of electrical stimulation of viseral afferent nerve fibres on monosynaptic and polysynaptic reflex responses

Evans¹,

McPherson²

1960

The Journal of Physiology

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The first investigation of the nature and time course of viscero-somatic interaction was made by Downman (1955) in anaesthetized, decerebrate and spinal cats. Later, Evans & McPherson (1958) showed that electrical stimulation of the afferent fibres in the sympathetic chain or splanchnic nerves facilitated monosynaptic reflexes and inhibited long-latency polysynaptic reflexes elicited from the hind-limb nerves of chloralosed and spinal cats. The present paper describes additional features of these interactions, and the interactions that follow stimulation of the pelvic, hypogastric and vagus nerves. METHODSThe experiments were carried out on forty cats weighing 1-7-5-9 kg, anaesthetized with intravenous chloralose (70 mg/kg); in a few of these the spinal cord was later transected at the level of C 2. Some cats were decerebrated under ether anaesthesia; details of the decerebration procedure have been given in a previous paper (Evans & McPherson, 1959). In order to maintain the cats in good condition all operative procedures were carried out while keeping the cat's rectal temperature between 31 and 330 C. In addition, 5 % (w/v) sterile glucose solution was infused intravenously at a rate of about 0-25-1 ml./min throughout the experiment. Before decerebration the cut edge of the skull was plugged with a mixture of bone wax and talc as the bone was removed. The urinary bladder was kept empty throughout all experiments by means of an indwelling catheter.The hypogastric and pelvic nQrves were stimulated by means of conventional indwelling platinum electrodes. Stimulation of other nerves and nerve roots and also recording from them was similar to the technique described previously (Evans & McPherson, 1958).

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“…They concluded that these reflex volleys also depended on a pathway through the medulla. However, there is AUTONOMIC SPINAL REFLEXES 715 evidence that the cardiovascular system retains some capacity for reflex adjustment in the absence of supraspinal centres (Sherrington, 1906;Langley, 1924;Sahs & Fulton, 1940; Kuntz, 1945;Downman & McSwiney, 1946;Richin & Brizzee, 1949; Mukherjee, 1957). The present experiments were carried out to examine features of the central organization of certain sympathetic reflex volleys carried in nerves which might be concerned in cardiovascular function.…”

Section: Introductionmentioning

confidence: 99%