Microcirculation of the small intestine in various phases of its motor activity

Experiments on guinea pigs, rabbits, and rats with simultaneous recording of motor activity of the small intestine and the state of its microcirculation showed that the diameter of the intramural vessels of the intestine depends on its contractile activity. On the basis of their data the authors suggest an explanation for the mechanism of disturbance of the secretory and absorptive function of the small intestine after blocking of its nervous reflexes and transplantation.Department of Anatomy, Patrice Lumumba Peoples' Friendship University. Laboratory of Physiology, Research Institute of Obstetrics and Gynecology, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kovanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 261–263, March, 1976.     

Vagal regulation of microhemodynamics and oxygen supply to the small intestine muscles

Three days after subdiaphragmal vagotomy, the rate of local blood flow in the muscular layer of rat jejunum increases, decreases on the 7th–30th day, and is normalized on the 60th–220th day. Po₂ is lowered within 3–30 days, but not after 14 days. Microhemodynamic disturbances are accompanied by changes in the configuration of the microvessels, increased permeability of their walls, and modification of the aggregation status of the blood. Correlations between the dynamics of blood flow rate, its kinetic parameters, and Po₂ on the one hand, and morphological reorganization of the microcirculatory bed, on the other, suggest that hypoxia of the small intestine muscles developing after vagotomy has a circulatory nature. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 8, pp. 142–146, August, 1998.     

Changes of the total water content and magnetic relaxation characteristics of the liver and small intestine in vagotomy

Bilateral subdiaphragmatic truncal vagotomy in rats results in a disturbance of water metabolism in the liver and small intestine which manifests itself in an increase of the total water content, prolongation of the spin-lattice and spin-spin relaxation, and in a distortion of the correlation between them. The dynamics of water metabolism is of a onepeak nature in the liver with a maximum after 7 days, whereas in the small intestine it is of a dual-peak type with peaks at 7 and 30 days. Near-normalization of the water balance in the digestive organs occurs 220 days later. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 10, pp. 442–444, October, 1995 Presented by P. V. Sergeev, Member of the Russian Academy of Medical Sciences     

The correction of postvagotomy disturbances of small intestine motility with antihypoxants and antioxidants

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 8, pp. 132–134, August, 1993     

Mechanism of vagal inhibition of small intestine contraction

The mechanism of inhibition of small intestine contraction in response to weak stimulation of the peripheral end of the vagus nerve cut at the cervical level was studied in experiments on anesthetized dogs. This inhibition can be blocked with arfonade or hexamethonium, atropine, and rausedyl, as well as by combined, but not individual administration of propranolol and dihydroergotoxine. We assume that inhibition is triggered by the release of catecholamines from sympathetic postganglionic terminals in response to activation of their muscarinic receptors induced by acetylcholine released from parasympathetic terminals during excitation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 2, pp. 135–138, February, 2000     

Adrenosensitive neurons of the myenteric (Auerbach's) plexus

Experiments on the myenteric plexus of isolated strips of the small and large intestines showed the presence of adrenosensitive cells capable of responding to application of different concentrations of adrenalin (A) and noradrenalin (NA) by a distinct increase in firing rate. The greatest effect was obtained with NA; the range of action of which was wider (from 10^–9 to 10^–5 g/ml) than that of A. Addition of phentolamine to the surrounding solution in most cases prevented the appearance of these effects. Besides spontaneously discharging cells, silent neurons with no spontaneous activity also responded to the addition of A and NA. It is suggested that catecholamines may play a direct part in the modulation of processes carried out by neurons in the ganglia of the myenteric plexus.Laboratory of Physiology of the Autonomic Nervous System, I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 3, pp. 259–261, March, 1977.     

Effect of local ischemia on the viability of the small intestine in different ages

Ligation of 8–10 pairs of straight vessels was carried out in analogous morphofunctional sites of the small intestine of dogs of different ages. Ischemia developed on part of the organ and antioxidant activity of the blood increased in younger but not in older animals. This may be due to a decrease in the number of functioning capillaries and pronounced arteriovenous shunting. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 474–476, February 3, 1998     

Effect of blood loss on nitric oxide content in liver and mucosa and muscle layer of small intestine in rats

Moderate blood loss (20 ml/kg) increases NO content in the intestinal mucosa and muscle layer, and especially, in the liver, as revealed byin vivo nitric oxide (NO) binding with Fe²⁺-diethyldithiocarbamate complex yielding paramagnetic mononitrosyl iron complexes. Enhanced NO synthesis after blood loss prevents vascular spasm in the mucosa, thus maintaining blood circulation and effective absorption in the small intestine. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 8, pp. 153–156, August, 1999     

Correlation between the level of motor activity on the small intestine and hexokinase activity in its muscular layer

Correlation between the motor activity of the small intestine and the intensity of energy formation in its muscular layer was studied. Significantly higher hexokinase activity was observed in the muscles of the duodenum than of the jejunum and ileum. Statistically significant differences in hexokinase activity were not found between the jejunum and ileum. Hexokinase activity was found to vary considerably and to correlate directly with the level of motor activity of the muscular layer, which forms the contractile system of the intestine.Academician K. M. Bykov Department of Physiology of Visceral Systems and Laboratory of Cytology, Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR S. V. Anichkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 3, pp. 260–263, March, 1978.     

Metabolism of nitrazepam in the intestine of albino rats

In the rat intestine nitrazepam is transformed to an amine and acetamide. In the duodenum and small intestine the reduction of nitrazepam and its subsequent acetylation are catalyzed by enzymes in the mucosa. In the cecum and large intestine these processes are due to the action of the microflora and tissue enzymes, and in the rectum to the action of the microflora alone.Laboratory of Psychotropic Preparations, I. I. Mechnikov Odessa University. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 7, pp. 53–56, July, 1977.     

Impact of exogenous oxytocin on the motor function of the mammalian small intestine in the lactotrophic period

The establishment of the motor function of the small intestine during postnatal ontogeny and the impact of exogenous oxytocin on this function in the lactotrophic period were examined in rats. In the first week of life, only peristaltic movements of the small intestine were detectable, possibly due to the weak development of the longitudinal and circular muscle layers in the small intestine wall. Oxytocin was found to have an inhibitory effect on small intestine motor activity in rat pups. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 230–233, September, 1994 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Intracellular study of electrical activity of Auerbach's plexus in guinea-pig small intestine

Intracellular recording revealed two general categories of ganglion cells in Auerbach's plexus. The characteristics of one category were relatively low resting potentials, high input resistance, discharge of spikes throughout a depolarizing current pulse, stimulus-evoked synaptic potentials and spontaneous electrical activity. Characteristics of the second category were high resting potentials, low input resistance, spikes only at the onset of a depolarizing current pulse and long duration hyperpolarizing after-potentials. Responses to extracellular electrical stimulation of the ganglia and interganglionic fiber tracts consisted of electrotonic spread of spikes from the processes to the cell soma, somal action potentials and depolarizing and hyperpolarizing responses that were probably EPSPs and IPSPs. Some of the neurons which received excitatory synaptic input responded with a prolonged train of spikes that outlasted by many seconds the duration of the stimulus to the fiber tract. Spontaneous electrical activity consisted of single EPSPs, patterned bursts of spikes that originated in the cell processes and spread electrotonically to, the recording site, IPSPs and action potentials. The burst-type activity showed periodic conversions from a burst pattern to a trainlike pattern of continuous discharge. Spontaneous discharge of single action potentials was superimposed upon a background of continuous synaptic input to the cell. Spontaneously occurring hyperpolarizing potentials were converted to depolarizing potentials when the membrane was hyperpolarized by current injected through the recording electrode. This work was supported by BMVg In San and National Institutes of Health AM 16813     

Quantitative determination of sodium excretory factor in biological fluids

Quantitative determination of sodium-excretory factor was carried out on isolated everted segments of rat jejunum. After addition of the test blood plasma to the incubation medium changes in absorption of fluid by the intestinal epithelium were recorded. The quantity of sodium-excretory factor capable of completely blocking the transport activity of the intestinal epithelium was taken as one intestinal unit of sodium excretory factor.Department of Pharmacology, Chernovtsy Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 624–625, November, 1978.     

Absorption of carbohydrates and fats in an allogeneic graft of the small intestine

The results of a study of the absorptive function of an allogenic graft of the small intestine, using D-xylose loading and electron-microscopic investigation of neutral fat transport in the intestinal wall, are described. An unusual increase in the absorption of D-xylose was shown to take place in association with structural changes in the wall of the intestine and disturbance of fat transport.Central Research Institute of Gastroenterology and Department of Operative Surgery and Topographical Anatomy, Patrice Lumumba Peoples' Friendship University, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. Kh. Vasilenko.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 2, pp. 153–156, February, 1977.     

Effect of mesodiencephalic modulation on small intestinal mucosa after massive blood loss in rats

Effect of mesodiencephalic modulation on small intestinal mucosa was studied in rats subjected to massive blood loss. Massive blood loss induced structural changes in intestinal epitheliocytes typical of tissue hypoxia: intraintestinal edema, mitochondrial alterations, and microcirculation disturbances. A single session of mesodiencephalic stimulation carried out 60 min after massive blood loss produced a pronounced adaptive effect, restored disturbed structure of the intestinal villi, and induced compensatory hypertrophy of the mitochondria. This suggests that mesodiencephalic modulation promotes normalization of intracellular energy metabolism, improves the absorption capacity of bordered enterocytes, and restores the disturbed intestinal barrier. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 11, pp. 519–523, November, 2000     

Role of activation of cholinergic influences in recovery of electrical activity of the stomach and small intestine during the early postoperative period in rats

The effects of neostigmine and calcium pantothenate on electrical activity of the stomach and small intestine were studied in chronic experiments on rats after laparotomy with implantation of a probe into the jejunum and electrodes into different portions of the gastrointestinal tract. At the early terms after surgery, stimulation of endogenous acetylcholine release intensified electrical activity of the stomach, duodenum, and jejunum. Treatment with neostigmine and calcium pantothenate did not accelerate the recovery of the migrating myoelectrical complex, but promoted the recovery of the general intensity of action potential generation in the stomach and small intestine. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 2, pp. 152–154, February, 2007     

Effect of muscular exertion on invertase activity of the small intestine

Invertase activity of the proximal, middle, and distal parts of the small intestine after muscular exertion lasting 2, 4, and 10 h (forced swimming in water at 35±1°C) was studied in acute experiments on male albino rats. After swimming for 2 h the invertase activity in the first two parts of the intestine was sharply reduced and it returned to its initial level after 48–72 h. This decrease was much less marked in the distal portion. Swimming for both 4 and 10 h led to a slight increase in enzyme activity in all three parts of the intestine 24 h after the beginning of the experiments, followed by a decrease in the first two parts and a marked increase in the distal portion 48 h after the beginning of the experiment. It is suggested that these changes are brought about through the hypothalamic-pituitary-adrenal system in accordance with the principle of the general nonspecific adaptation syndrome.Laboratory of the Physiology of Digestion and Laboratory of General Physiology, Institute of Physiology, Academy of Sciences of the Uzbek SSR, Tashkent. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1335–1337, November, 1976.