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Læknablaðið - 15.08.1995, Page 42

Læknablaðið - 15.08.1995, Page 42
618 LÆKNABLAÐIÐ 1995; 81 Nýr doktor í Þann 24. nóvember 1994 varði Einar Stefán Björnsson, læknir á lyflækningadeild Sahlgren- ska sjúkrahúsins í Gautaborg, doktorsritgerð í læknisfræði við Háskólann í Gautaborg. Rit- gerðin nefnist Interdigestive gastrointestinal motility in humans. Studies with special refer- ence to small intestinal peristalsis. Agrip úr rit- gerðinni fer hér á eftir: The interdigestive motility of the upper gut is characterized by the migrating motor com- plex (MMC), which is a cyclic pattern of activ- ity of both motility and secretion. The MMC consists of phase I with motor quiescence, phase II with irregular contractions, and phase III with motor activity at the maximal rate of the stomach and the small intestine. The func- tional significance of the MMC still remains uncertain and the specific function of the dif- ferent phases has yet to be explained. In partic- ular, little is known about the characteristics of individual contractions in the different phases of the MMC, their direction of migration and velocity of migration. The present study was initiated to analyse the MMC in detail by computerized recordings of the stomach and the proximal small intes- tine, with special focus on individual contrac- tions in the duodenum. Pressure recordings were performed in the upper gut by antroduo- denojejunal manometry in healthy subjects. Multichannel pressure catheters were used with tightly spaced side holes, constructed for the study of individual contractions. In the proximal duodenum the mean pro- portion of retroperistaltic pressure waves, out of all propagating waves, was significantly in- creased in the last part of phase III of the MMC (85%), compared with early phase III (6%), late phase II (6%) and the feeding phase (10%), irrespective of gender, order of the MMC cycle and previous tubeexperience of the subjects. This retroperistaltic pattern was Key words; Computerized recording; erythromycin; duo- denum; gastrointestinal motility; hyperglycemia; insulin; manometry; motilin; pancreatic polypeptide; peristaisis; propranolol; time window. læknisfræði also found in the distal duo- denum but not in the proximal jejunum. In the last part of phase III in the proximal duo- denum, the motility index decreased in orad direction (p<0.01) and the contraction frequency had a marked orad gradient (p<0.05). The phase III-like activity in the duodenum induced by the macrolide erythro- mycin was also characterized by retroperistal- sis in the last part of the phase, similar to the naturally occurring one. The phase III-related retroperistalsis was not altered by acute hy- perglycemia, by euglycemic hyperinsulinemia, or by beta adrenergic blockade by proprano- lol. However, hyperglycemia was shown to re- duce the motility index in late phase II, not only in the gastric antrum (p<0.01) but also in the small intestine (p<0.01). Furthermore, during euglycemic hyperinsulinemia, similar effects were obtained as during hyperglyce- mia, with a complete absence of phase III in the antrum and a shorter duration of phase III in the proximal duodenum (p<0.05). The present findings show that the last part of phase III behaves like a retroperistaltic pump. This distinct retroperistaltic pattern seem to be confined to the duodenum, since it was not observed in the proximal jejunum. This cyclic retroperistalsis was not affected by the different pharmacological and metabolic conditions studied and may be the motility phenomenon behind the recently reported cy- clic alkalinization of the gastric antrum. Its role in functional and organic motility disor- ders warrants more experimental and clinical studies.

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