Impairment of the absorptive function of the colon in irritable bowel syndrome and nonspecific ulcerative colitis

The dissertation is devoted to the investigation of disturbances of the absorptive function of the colon in patients with irritable bowel syndrome and nonspecific ulcerative colitis. The work is aimed at evaluating the absorptive capacity of the colon by means of the rectal antipyrine test, as well as at correlating the data obtained with the results of morphological and morphometric investigation of mucosa biopsy specimens, electrocolographic study of motor activity and analysis of the quantitative and qualitative composition of the intestinal microflora. The investigation covers the clinical characteristics of the patients, the dynamics of absorption in different forms and activity of the diseases and the possibility of using the test for the optimization of rectal therapy. The results obtained clarify the pathogenetic mechanisms of absorption disturbances and are of clinical and diagnostic importance for the selection of rational therapy.

The absorption of water and electrolytes is one of the principal functions of the colon. The domestic and foreign literature contains a large number of works devoted to the normal physiology of the processes of absorption and secretion of water and electrolytes in the colon. At present, thanks to the application of the newest methods of investigation (the use of the achievements of the doctrine of cell membranes, modern methods of biochemistry, biophysics and histochemistry, electron microscopy, radionuclide methods, and investigations at the molecular level), physiologists have accumulated substantial material concerning the transport of various substances through the epithelium of the gastrointestinal tract. Knowledge of the mechanisms of absorption and secretion makes it possible, when necessary, to intervene in these processes, which is of considerable practical importance.

The colon plays an important role in the absorption of water and mineral substances. Under a standard diet it absorbs daily 1.4–1.9 litres of fluid, 206 mmol of Na+ and 103 mmol of Cl− [40,84,94].

The domestic and foreign literature contains a large number of works devoted both to topographic anatomy [10,22,26], the mechanisms of absorption of water and ions [80,81,84,86,107], and the regulation of water and electrolyte transport [94,96,130,131,146,160]. Nevertheless, investigations of the absorptive function of the human colon in vivo in health, and especially in intestinal diseases, are limited and their results are contradictory.

The few investigations of water and electrolyte transport in the colon and of the absorption of certain drugs in its inflammatory diseases indicate considerable disturbances of this function [4,18,32,123,147]. However, the character and degree of these disturbances in different forms, activity and course of ulcerative colitis require further study and are of considerable importance for the development of adequate drug therapy.

Changes in the absorptive function of the colon in functional intestinal diseases have also been studied in only a small number of investigations [1,34,74], whereas irritable bowel syndrome is one of the most common gastroenterological diseases in the adult population [14,16,19,28,39,76,95].

In recent years the problem of chronic constipation has acquired great relevance. The works devoted to the study of its pathogenesis are mainly confined to recording disturbances of the motor activity of the colon due to various causes [15,25,36,47,58,75,89]. The literature lacks data that would allow one to judge how and to what extent the processes of absorption in the colon are disturbed in constipation. Therefore further investigations of the interrelations between fluid absorption and the motor-evacuatory function of the colon are necessary.

The study of the absorptive capacity of the colon in various pathological states is of definite practical interest and may be of great importance for a better understanding of the pathogenesis of these diseases, for the selection of more rational therapy and for evaluating its effectiveness.

THE AIM OF THE WORK is to evaluate the absorptive function of the colon in irritable bowel syndrome and nonspecific ulcerative colitis and to determine its clinical and diagnostic significance.

OBJECTIVES OF THE INVESTIGATION:

1. To evaluate the possibilities of the rectal antipyrine test for studying the absorptive function of the colon.

2. To study the absorptive function of the colon in patients with irritable bowel syndrome and nonspecific ulcerative colitis and to determine the degree of its disturbance.

3. To study the character of the morphological and morphometric changes of the colonic mucosa.

4. To determine the features of the motor activity of the colon.

5. To carry out an evaluation of the quantitative and qualitative composition of the colonic microflora.

6. To establish the dependence of disturbances of the absorptive capacity of the colon on the character of the morphological changes of the mucosa, the motor activity and the state of the colonic microflora.

7. To determine the clinical and diagnostic significance of the revealed changes in the absorptive capacity of the colon.

SCIENTIFIC NOVELTY

For the first time the rectal antipyrine test has been used to determine the absorptive capacity of the colon. It has been shown that, in the absence of hepatic dysfunction, this test can serve as a simple and informative method for evaluating absorption in the distal parts of the intestine.

For the first time disturbances of the absorptive function of the colon have been revealed in patients with irritable bowel syndrome and have been associated with the type of motor activity and the data of morphometric investigation of the colonic mucosa.

In patients with nonspecific ulcerative colitis, both a decrease in antipyrine absorption and its sharp intensification under conditions of a pronounced destructive inflammatory process in the colon have been found, which must be taken into account in the rectal administration of anti-inflammatory drugs.

PRACTICAL SIGNIFICANCE OF THE WORK

The rectal antipyrine test can be used for diagnostic purposes to evaluate the absorptive function of the colon in inflammatory and functional diseases.

The rectal antipyrine test can be used to optimize the doses of drugs administered rectally. When studied dynamically, this test can serve as a criterion of the effectiveness of the therapy carried out or of the irreversibility of the morphological changes in the colonic mucosa.

With the help of the rectal antipyrine test it is possible to select drugs capable of exerting an inhibitory or stimulating influence on the absorptive capacity of the colon, which will make it possible to increase the effectiveness of treatment and to reduce the frequency of systemic complications in patients with nonspecific ulcerative colitis.

APPROBATION OF THE WORK:

The main propositions of the dissertation were presented at the XXVII, XXVIII and XXIX scientific sessions of the Central Research Institute of Gastroenterology (Moscow, 2000, 2001, 2002), and at the VIII Russian National Congress «Man and Medicine» (Moscow, 2001). On the materials of the investigation 9 scientific works have been published and methodical recommendations have been issued.

VOLUME AND STRUCTURE OF THE DISSERTATION:

The dissertation consists of an introduction, a review of the literature, a description of the material and methods of investigation, an exposition of the results of original investigations and a conclusion.