[Investigation of the evacuatory function of the gastrointestinal tract in 5-day dry immersion].

Six male volunteers for dry immersion (DI) modeling the microgravity effects on human organism were subjects in the GI evacuatory function investigation. The investigation was aimed to evaluate liquid food evacuation from the stomach (13C-acetate test) and time of chymus orocecal transit (H2-inulin test). The 13C-acetate test did not reveal changes in stomach evacuatory activity after 4 days in DI. The H2-inulin test demonstrated shortening of chymus transit along the small intestine and extension of chymus passage from the ileum to cecum. Subsequent reduction of inulin metabolism in the large intestine suggested inhibited passage of these GI segments. The results showed that stability of liquid evacuation from the stomach and acceleration of chymus transit along the small intestine hinder evacuation of the large intestine content which is the primary cause for inhibition of GI evacuatory activity in DI.

[Secretory activity of the stomach during modeling of increased filling of abdominal veins].

Determination of the stomach secretory activity and ultrasonic investigation of the gastroduodenal organs and vessels were performed in test-subjects tilted at -12 degrees and -15 degrees. Short HDT(12-24 hrs.) as a hypokinesia factor was minimized which caused enlargement of the parenchymatous and thickening of walls of the hollow organs. Increased filling of the abdominal veins was paralleled by rise in pepsinogen levels in blood and urine, and increase in the intravitelline content in fasting subjects. Elevated tone of the pylorus and retarded evacuation from the stomach indicated active hydrochloric acid secretion. Concurrently, bile and pancreas juices were secreted more profusely and intestinal content in the duodenum increased. It was shown that modeled increase of abdominal vein filling stimulates secretion as by fasting stomach so by the liver and pancreas.

[State of the abdominal organs and vessels on the background of simulated venous plethora in the splanchnic vascular system].

Ultrasonic investigations of the abdominal organs and splanchnic veins were performed in essentially healthy subjects tilted at 12 degrees and 15 degrees for the period of 12 hrs. and 24 hrs. Tilting produced typical redistribution of venous blood and body liquids toward the cranial end. In its turn, blood redistribution caused excessive venous plethora and abdominal stasis. These were succeeded by expansion of large veins in the abdomen, enlargement of parenchymal organs and contraction of their echogenicity, and thickening of the hollow organs walls. Changes in the gastrointestinal functions before meal included elevated gastric, hepatic and pancreatic secretion, and an increased amount of intestinal content. The investigations demonstrated that stasis of the splanchnic veins altered functioning of the digestive organs in tilted human subjects.

[The functional status of the human stomach in the course of the experiment with antiorthostatic hypokinesia of 4 months duration].

The paper deals with type of changes in gastroduodenal organs associated with hypersecretion of the stomach induced by simulation of some effects of microgravity. Subjects in the investigation were 13 males volunteered for a 4-month bedrest study. Biochemical changes in blood, urine and gastric juices were analyzed in comparison with ultrasonic images of the gastroduodenum organs and data of stomach and duodenum endoscopy. The investigations showed increased blood and urine levels of pepsinogen indicative of gastric hypersecretion characterized by more intensive secretion of gastric juices, lowered pH, elevated pyloric tone, activation of duodenal secretion and cholepoiesis. Gastric hypersecretion was concomittant to the development of plethora in the abdominal veins. The highest gastric secretion was observed after two months of bed rest. Further bed rest extension was marked by fading of the signs of hypersecretion by the stomach and appearance of some signs of chronic stress. Our results expand the knowledge of changes in the gastroduodenal organs during bed rest, space flights and other conditions provocative of the hypersecretory transformation of the stomach.

[Cutaneous electro-gastroenterography for evaluation of changes in the gastrointestinal tract in consequence of various angles of inclination and length of head-down tilt].

Experimental results were compared with data of cutaneous electro-gastroenterography and USI of the gastrointestinal tract in human subjects at different tilt angles and after different periods of tilting. It was shown that increased GIT electrical activity in tilted subjects before meal is representative of increasing intracavetary contents of the stomach and small intestine. More intensive electrical activity results from elevation of the GIT tone and peristalsis. Extension of tilt duration raises GIT tone and peristalsis and, consequently, stimulates the GIT electrical activity. Further increase of the tilt angle suppresses evacuation and, therefore, the electrical activity Analysis of the results allows conclusion that increased parameters of the total energy of GIT electrical potentials are reflective of elevated tone of GIT walls, whereas elongation of the potential peaks envelope implies activation of peristalsis.

[Modified methods of percutaneous electrogastroenterography]. / Modifitsirovannaia metodika nakozhnoi élektrogastroénterografii.

In 62 normal males and females gastrointestinal (GI) electrical activity was evaluated before and after standard breakfast with the method of epicutaneous electrogastroenterography (EGEG) with the use of AgCl electrodes and original hard- and software "Gastroenterograph" developed by the authors. Spectral analysis (SA) of GI electrical potentials enabled quantification of the electrical activity of the stomach, duodenum, jejunum, ileum and the whole of the small intestine. The stomach and the small intestine were main contributors to the total GI electrical activity during fasting. Changes in the functional activity of the digestive system after the meal were characterized by increases in selected SA parameters (length of the spectral curve and area underneath), dissociation between their values and redistribution of ratios in different GI segments.

[Results of studies of carbohydrate metabolism and ultrasonography of the pancreas in man after continuous anti-orthostatic hypokinesia]. / Rezul'taty issledovanii sostoianiia uglevodnogo obmena i ul'trazvukovoi kartiny podzheludochnoi zhelezy u cheloveka pri dlitel'noi antiortostaticheskoi gipokinezii.

Data on the hypokinesia-induced transformation of the glycemic profile and ultrasonic changes in the pancreas structure are presented. The AOH study gave further evidence of transforming glycemic curves. Moreover, increased sizes of tail and head of the pancreas and a decrease in its echogeneity were observed in all test-subjects. Structural changes in the pancreas were confirmed by biochemical investigations which revealed increased levels of blood enzymes and activation of insulin secretion. Increases in the liver size, thickness of the wall of the stomach, diameter of the splenic vein were indicative of progressing venous plethora in the portal vein system. It was shown that venous plethora are the main cause for changes in the upper GI, and in the pancreas state in particular, which can be qualified as dysfunctional. These structural changes in the pancreas could suppress its functional activity manifested by increases in blood enzymes and hormones and transformation of the glycemic profile during the glucose load.

[Carbohydrate hydrolysis, transport and utilization during limited motor activity in rats]. / Gidroliz, transport i utilizatsiia uglevodov pri ogranichenii dvigatel'noi aktivnosti u krys.

Carbohydrate hydrolysis, transport and utilization were investigated in rats exposed to diminished motor activity for 90 days. Glycemic curves were examined using provocative tests with equivalent quantities (1.5 g/kg body weight) of poly-, oligo- and monosaccharides (starch, maltose, glucose). Simultaneously, carbohydrases were measured in the homogenates of the pancreas, duodenal mucosa and small intestine as well as radioimmune insulin and glucagon were determined in blood. In the course of hypokinesia carbohydrate hydrolysis, transport and utilization varied in a different manner. At the beginning of exposure the activity of carbohydrases responsible for carbohydrate hydrolysis in the cavity and membranes increased which was accompanied by hyperglycemia and rapid utilization of carbohydrates. This is associated with nonspecific reactions to hypokinesia and higher requirements of the body for the energy substrate. By hypokinesia day 30 carbohydrate hydrolysis and transport were inhibited, hypoglycemia developed but glucose utilization remained unchanged. At a later stage of exposure the system of carbohydrate hydrolysis and transport showed an adaptive reaction; inhibition of pancreatic amylase was accompanied by accelerated enzyme transport in the small intestine and glucose resorption. In this situation the glycemic curves became extended suggesting a delay in glucose utilization. The latter was induced by changes in the endocrine compartment of the pancreas.

[Digestive function of the small intestine and pancreas in rats on artificial feeding]. / Sostoianie pishchevaritel'noi funktsii tonkoi kishki i podzheludochnoi zhelezy krys v usloviiakh iskusstvennogo pitaniia.

Full-value diets of similar composition were given to male rats weighing 207-230 g, by intravenous (group 1) or intragastric (group 2) routes. The proportion of amino acids, fats and carbohydrates was 9.9:15.7:74.4 (with regard to their calorific value). The diet calorific value comprised 60.6 kcal/rat/day. An average mass increase in group 1 was 2.44 +/- 0.14 g/day, in group 2 - 1.75 +/- 0.11 g/day. The protein content and activities of alpha- and gamma-amylase, invertase, maltase, and glycil-L-leucine dipeptidase were assayed in the intestinal mucosa of the proximal portion of the small intestine in group 1 rats, while a decreased alpha-amylase activity in the distal portion of the small intestine was recorded in the animals of group 2. The mass of the pancreas in the rats of group 1 and 2 was authentically lower than in the control rats which received oral feeding with natural foods. The lowest mass of the pancreas was observed in the rats of group 1. Specific activity of trypsin, lipase and RNase in the pancreatic tissues of rats in groups 1 and 2 was similar. The results of the study have evidenced a lowered function of the digestive system under conditions of artificial feeding, especially in case of intravenous nutrition.

[Effect of enkephalin analogs on various digestive functions during restriction of motor activity]. / Vliianie analoga énkefalinov na nekotorye pishchevaritel'nye funktsii pri ogranichenii dvigatel'noi aktivnosti.

Rats were exposed to 7-day hypokinesia and the effect of an enkephalin analog on the secretion of pepsin, amylase, the shape of the glycemic curve and the secretion of gastrointestinal hormones, gastrin and insulin, was investigated. The hypokinetic exposure increased pepsin in the gastric mucosa and amylase in the pancreas, and decreased glycemia and insulin secretion. The analog normalized exo- and endocrine function of the pancreas and the shape of the glycemic curve.

[Functional state of the gastrointestinal tract organs in rats after a flight on the Kosmos-1129 biosatellite]. / Funktsional'noe sostoianie organov zheludochno-kishechnogo trakta posle poleta na biosputnike "Kosmos-1129".

The enzyme-excretory and motor functions of the gastrointestinal tract of rats flown for 18.5 days onboard the biosatellite Cosmos-1129 were studied. Immediately postflight, the pepsin synthesis decreased and the dipeptide parietal hydrolysis increased. At R + 6, the activity of the enzymes responsible for the cavitary and parietal hydrolysis of lipids significantly grew and that of the enzymes involved in protein hydrolysis fell. At R + 30, the carbohydrate hydrolysis was inhibited and the activity of lipolytic enzymes enhanced markedly. The amplitude and rhythm of stomach biopotentials were dysbalanced. The so-called immobilization stress of intact rats brought about activation of lipase, monoglyceridyl lipase, dipeptidase and inhibition of amylase and invertase. The immobilization exposure of flight rats caused inhibition of the membrane hydrolysis of proteins and carbohydrates and lack of the pancreatic reaction.