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  • 11
    ISSN: 1619-1560
    Schlagwort(e): Colon ; Constipation ; Inhibitory junction potential ; Large intestine ; Smooth muscle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Preparations of the circular muscle layer from the sigmoid colon resected from patients with idiopathic chronic constipation were compared, at an electrophysiological level using the sucrose-gap technique, with preparations of the same region of the intestine resected from patients with rectal carcinoma. Non-adrenergic, non-cholinergic inhibitory neuromuscular transmission, represented by inhibitory junction potentials, was present in preparations from both groups. However, the inhibitory response in preparations from constipated patients had a slower or longer time-course than in those from cancer patients. Also, rebound activity following inhibitory transmission was observed in 34% of preparations from constipated patients but was observed in 67% of preparations from cancer patients. Preparations from both groups displayed the same patterns of spontaneous activity and the same proportion of each group was quiescent. The threshold for generation of action potentials and the passive resistance of the smooth muscle membrane were the same in both groups. However, quiescent preparations from constipated patients were less likely to discharge trains of action potentials when the smooth muscle membrane was depolarized than were preparations from cancer patients. These changes in transmission processes and excitability in tissue from constipated patients are discussed in relation to altered states of colonic motility found in people with idiopathic chronic constipation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    ISSN: 1573-2568
    Schlagwort(e): adrenergic innervation ; fecal incontinence ; internal anal sphincter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Physiological and histological studies have shown that the internal anal sphincter is abnormal in idiopathic fecal incontinence. We have recently demonstrated that the invitro contractile response of the internal anal sphincter to the sympathetic neurotransmitter noradrenaline is decreased in incontinence. In this study we have further defined this reduced sensitivity and provided more information about the intrinsic innervation in both the normal and the incontinent sphincter muscle. Muscle strips from 12 incontinent patients undergoing post anal repair and from 11 controls undergoing rectal excision for low rectal carcinoma were studied. Responses to noradrenaline were recorded initially alone and then in the presence of phentolamine, an α-adrenoceptor blocker. In the presence of phentolamine, noradrenaline caused relaxation: there was no significant difference in the relaxation-response curves and the EC50 was the same in the two groups. These results demonstrate that the previously documented reduced sensitivity to noradrenaline is due to an altered sensitivity of the α-adrenoceptors. Electrical field stimulation produced relaxations in all muscle strips, but only in the controls was the magnitude of the relaxation significantly increased in the presence of phentolamine. This indicates that there is an α-adrenergic excitatory component of the response to electrical field stimulation of the intramural nerves, which was present in tissues from control patients but which was absent in tissues from patients with idiopathic fecal incontinence.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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