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At least 19 recordsLinked to original sources
PubMed1997

Electrophysiological characteristics of submucosal neurones in the proximal colon of guinea-pigs: comparisons with caecum and descending colon.

A systematic examination has been made of the active and passive electrophysiological properties and synaptic inputs of forty-four randomly impaled submucosal neurones in the proximal colon of the guinea-pig to compare these characteristics directly with those of submucosal neurones in the caecum (n = 70) and descending colon (n = 45). Within each of the three electrophysiological classes of submucosal neurones identified (S, S/AH and AH), no statistically significant regional differences were found with respect to the resting membrane potential, membrane time constant or input resistance between neurones of the proximal colon, descending colon and caecum. Of submucosal neurones from the proximal colon, forty-three of forty-four (98%) received fast excitatory synaptic potentials (fast EPSPs); thirty-nine (91%) were S neurones and the others were S/AH neurones; only one of the forty-four cells (2%) was an AH neurone. An idazoxan-sensitive slow inhibitory postsynaptic potential (slow IPSP) was induced in thirty of forty-three S and S/AH neurones (70%) of the proximal colon, compared with sixty-one of sixty-six caecal neurones (92%) and twelve of forty-one neurones (29%) in the descending colon. The mean (+/- S.E.M.) amplitude of the slow IPSP in proximal colonic neurones was 17 +/- 1 mV (range, 6-30 mV; n = 30), compared with the significantly larger synaptic response (25 +/- 1 mV; range, 7-38 mV; n = 66; P < 0.05) recorded in the caecum; the mean slow IPSP amplitude in the descending colon was significantly smaller (12 +/- 2 mV; range, 5-27 mV; n = 12; P < 0.05) than that in the caecum. In the proximal colon and caecum, only those neurones with a slow IPSP had a hyperpolarizing response to noradrenaline, whereas about 50% of those neurons of the descending colon that lacked a slow IPSP were hyperpolarized by noradrenaline, acting via alpha 2-adrenoceptors. Thus, the electrophysiological characteristics of the submucosal neurones of the proximal colon more closely resemble those of the caecum than those of the descending colon, of which many do not have a functional noradrenergic synaptic input. Furthermore, the results confirm that there are fundamental regional differences in the guinea-pig large intestine with respect to the synaptic organization of submucosal neurones of particular electrophysiological classes.

Adrenergic alpha-Agonists↗
PubMed1994

[Surgical treatment of colonic fistulas with descending colon].

Radical operations were conducted on 50 out of 78 patients with coloperineal and colovaginal fistulas consequent upon resection of the colon and bringing out its segments into the anal canal. The fistulas recurred in 10 patients. Individual choice of the operative method and development of a system of pre-, intra-, and postoperative special methods should reduce the incidence of recurrences after such operations.

Anal Canal↗
PubMed1984

Cholinergic mechanism of sodium nicotinate-induced contractions in rat and guinea-pig descending colon.

In segments of rat descending colon 34.5 microM Na-nicotinate-induced rhythmic contractions that were late in onset, long lasting and reversible. The Na-nicotinate contractile effect was unaffected by 100 microM hexamethonium, whereas it was rapidly blocked by 30 nM scopolamine and inhibited by treating the samples with 20 microM hemicholinium-3, or 40 microM tetrodotoxin or 60 microM procaine, by incubation at 20 degrees C for 60 min or by removing CaCl2 from the incubation medium. In segments of rat descending colon exogenous acetylcholine induced an initial peak in developed tension followed by long lasting rhythmic contractions. Low indomethacin concentrations (from 3 to 60 microM) suppressed both Na-nicotinate and acetylcholine-initiated rhythmic contractile activity while a higher indomethacin concentration (0.6 mM) was required to abolish the acetylcholine-evoked first major contraction. Also in segments of guinea-pig descending colon 34.5 microM Na-nicotinate induced a contractile effect that was abolished by 30 nM scopolamine and almost completely absent in tissue samples treated with 20 microM hemicholinium-3 or exposed to low temperature. The data presented indicate that in segments of rat descending colon Na-nicotinate contractile activity is triggered by acetylcholine release from postganglionic nerve endings and that this cholinergic, calcium-dependent action appears to be modulated by a contemporary release of prostaglandin-like material. In addition, indication is given that this indirect mechanism can be responsible of the Na-nicotinate contractile action at the intestinal level in different animal species.

Acetylcholine↗
PubMed1979

Synchronous primary mucinous adenocarcinomas in the descending colon and perianal glands.

The descending colon is a relatively rare site for mucinous adenocarcinoma. Anal ductal malignancy and multiple primary coloperianal mucinous adenocarcinomas are also rare. We have described the unusual finding of multiple primary synchronous mucinous adenocarcinomas in the descending colon and perianal glands. There was no evidence of any metastasis from the Dukes B lesion in the descending colon.

Adenocarcinoma, Mucinous↗
PubMed1992

Microvascular circulation of the descending colon in horses.

The microvascular circulation of the descending colon was studied in 5 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, horses were euthanatized, and 3 segments of the descending colon and its mesentery containing 1 vascular arcade were removed from each horse. The fecal balls were gently massaged from the lumen, and the blood was flushed free of the circulation with isotonic NaCl. In 5 segments, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Specimens examined radiographically also were prepared for histologic examination, using standard methods. Ten segments were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. Arcuate arteries gave rise to a descending colonic rete that surrounded the vein and supplied numerous descending colonic lymph nodes. The rete also supplied the mesocolon and the descending colonic tissue. Short filamentous vessels arising from the rete directly penetrated the mesenteric tenia to supply an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. Larger vessels arising from either side of the rete divided into the long- and short-terminal arteries that supplied an extensive submucosal plexus, which was continuous around the circumference. The submucosal plexus supplied the mucosa, the tunica muscularis, and the serosa. Vessels running centrifugally from the submucosal plexus formed an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. The intermuscular plexus at the mesenteric angle also was supplied by vessels branching from the short-terminal arteries as they penetrated the muscularis externa.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

[Useful CT findings in a case of idiopathic perforation of the descending colon].

Idiopathic perforation of the descending colon is an uncommon disease. The disease has tendency to complicate with severe pan-peritonitis at relatively early stage. So early diagnosis and treatment is required. We encountered a 83-years-old female patient with idiopathic perforation of the descending colon. CT revealed the findings suggestive of free air in the retro-peritoneal space. We thought CT may be useful diagnostic approach to make correct diagnosis of the perforation of the colon.

Aged↗