Shinji Homma

Electrogastrography after operative repair of esophageal atresia

Esophageal atresia (EA) is a life-threatening disorder associated with operative complications. Post-operative gastric electrical control activity detected by a non-invasive electrogastrography (EGG) technique was investigated in 13 children aged 1–17 years to clarify whether gastric motility disorders were present. EGG abnormalities were present in 5 patients; persistent dysrhythmias were found in 3. Roentgenographic examinations showed mild gastroesophageal reflux in 3 (60%) of the dysrhythmic patients; 2 others had postprandial dysrhythmias. The mean spectral frequency (MSF) of EA cases with dysrhythmia was significantly higher than that of patients without dysrhythmia in both fasting and postprandial states (P < 0.05). The variability of the peak spectral frequencies (PSFV) in patients with dysrhythmia was significantly higher than in those without dysrhythmia in both fasting and postprandial states (P < 0.05). There were no significant differences in MSF and PSFV between EA patients without dysrhythmia and controls. These results suggest that gastric motor activity may be disordered in patients following operative repair of EA, although they remain asymptomatic. EGG may be a useful screening examination for postoperative gastric functional disorders.

Isopower mapping of the electrogastrogram (EGG)

Electrogastrograms (EGGs) were recorded simultaneously at 14 locations of the epigastric abdominal surface of the human. EGGs were spectrally analyzed by the maximal entropy method (MEM). Spectral frequencies were classified into five groups: 1 cycle per minute (cpm) (-2.4 cpm), 3 (2.5-4.9), 6 (5.0-7.4), 8 (7.5-9.9), and 10 (10.0-12.9). The maximal power peak (Zi) in each spectral group at a certain electrode location (Xi, Yi) was used as a representative (Zi = [Xi, Yi]). Horizontal line through the symphysis pubis was designated Yo and a line along the right thoraco-abdominal border was designated Xo. Thereafter, the usual geographic contour map program was used, and the isopower EGGs were determined and the maximal power spots were obtained for five spectral groups. The maximal power spots or foci for the 1 cpm group distributed evenly over the supra- and infraumbilical areas on a retouched and superimposed map. The distribution of the 3 cpm group spots was restricted mainly to the epigastric area. The epigastric 3 cpm spots may reflect the gastric electrical activity because of their location. The distribution of the 6 cpm group spots was essentially similar to that of the 3 cpm group. The spots of the 8 and 10 cpm groups were evenly distributed over the abdominal surface, similar to that of 1 cpm group. The infraumbilical 3 and 6 cpm spots may reflect colonic activity.

Postischemic Recovery Process of Renal Oxygen Consumption in Normal and Streptozotocin Diabetic Rats

We tried to study in depth the recovery process in the cortical and the medullary oxygen (O2) consumption of normal and streptozotocin diabetic rat kidneys after ischemia. It was found that the cortical and the medullary O2 consumption decreased after ischemia, reaching their lowest levels at 1 day after every ischemic duration in normal and diabetic kidneys. In the period prior to ischemia to 1 day after ischemia, no significant difference was seen in the decrease in O2 consumption between the cortex and the medulla in normal kidney, whereas the medullary O2 consumption significantly decreased compared with the cortical O2 consumption in diabetic kidney. From 1 day to 4 weeks after ischemia, the increase in the cortical O2 consumption was significantly higher than that in the medulla of normal kidney. In contrast, the increase in the medullary O2 consumption was significantly higher than that in the cortex of diabetic kidney. Consequently, up to 4 weeks after ischemia, the decrease in the cortical O2 consumption was significantly lower than in the medulla of normal kidney, while there was no significant difference regarding the decrease in O2 consumption between the cortex and the medulla in diabetic kidney. These results suggest that there is a clear difference in the postischemic recovery process of O2 consumption between the cortex and the medulla, and also between normal and diabetic rat kidneys.

Effects of furosemide on renal oxygen consumption after ischemia in normal and streptozotocin diabetic rats.

Normal and streptozotocin diabetic rats were subjected to ischemic injury by unilateral renal artery occlusion for 60 min. The cortical and the medullary oxygen consumption (QO2) in the postischemic and the control, contralateral nonischemic, kidneys were measured 1 h, 1 day, and 1, 2 and 4 weeks for normal rats and 1 day, and 1 and 4 weeks for diabetic rats after ischemia. The effects of furosemide on QO2 of the cortex and the medulla of normal and diabetic rats were studied. The diabetic kidney was more vulnerable to ischemic injury than the normal kidney. Furosemide-sensitive active transport function in the medulla of the diabetic kidney was higher than that of the normal kidney. Furosemide did not decrease the cortical QO2 significantly in the control and the postischemic kidneys of normal and diabetic rats. In contrast, the medullary QO2 of the control kidney in both rats was significantly reduced by furosemide at every period after ischemia. In the medullary QO2 of the postischemic kidney, there were no significant decreases at any period after ischemia in the diabetic rats and only after a 1-hour period for normal rats. However, 4 weeks after ischemia, there was no statistically significant difference in the medullary QO2 inhibition by furosemide between the control and the postischemic kidneys in both normal and diabetic rats. We conclude that the furosemide-sensitive active transport function in the medulla recovers by the 4th week after ischemia in normal and diabetic rats.

In vitro motor activity of intestinal segments of streptozotocin diabetic rats

The spontaneous motor activity of the isolated segments of the gut of streptozotocin-diabetic rats was studied in vitro. In normal preparations, the frequency of intraluminal pressure changes was little influenced by raising the intraluminal pressure. In contrast, in diabetic preparations, the frequency tended to increase with a rise of the intraluminal pressure, and the pressure waves were more irregular than in controls. The motor frequency with a pressure load of 3 cm H2O in the duodenum was 33/min in control rats and 21/min in diabetic rats. The motor frequencies in the other intestinal segments were also higher in normal preparations than in diabetic ones, although these differences were statistically not significant. The amplitude of intraluminal pressure changes increased according to the increase of pressure load, both in normal and diabetic preparations. These amplitudes were higher in normal than in diabetic preparations; however, the differences were statistically significant only in the jejunum. Insulin treatment (5 U/day) for one month, one to two months after streptozotocin injection, lowered the plasma glucose level to nearly normal and increased the body weight up to 80% of the normal but did not re-establish the normal motor frequency in the duodenum. Moreover, treatment of diabetic rats with aldose reductase inhibitor, ONO-2235 (per os, 50 mg/kg b.w./day for one month, one to two months after streptozotocin injection) did not re-establish the normal rhythms in duodenum. The pacemaker activity as well as mechanical properties in the intestinal tract may be disturbed in diabetic preparations.

Blood pressure and heart rate relationships during cervical sympathetic and vagus nerve stimulation in streptozotocin diabetic rats

Linear regressions were calculated between blood pressure and heart rate changes during the stimulation of peripheral cut end of cervical sympathetic and vagus nerve in the streptozotocin diabetic rats (65 mg/kg) and age-matched controls. Slopes of blood pressure (mmHg, abscissa)-heart rate (beat/minute, ordinate) relationships of diabetic rats (9.87 +/- 1.46, mean +/- S.E.M., n = 8) were significantly steeper (P < 0.05) than those of age-matched controls (5.12 +/- 0.63, n = 7). In the control rats, blood pressure and heart rate were rather equally changed during autonomic nerve stimulation. In contrast, in the diabetic rats, heart rate was markedly changed but blood pressure was little changed during the electrical stimulation of the cervical autonomic nerves. Chronotropic effect was exaggerated but inotropic one was disturbed in the heart of streptozotocin diabetic rat when cervical sympathetic nerve was stimulated.

Isopower mapping of electrogastrograms in short-bowel syndrome.

Methods for making topographic or isopower electrogastrographic (EGG) maps and for obtaining maximum power foci (MPFs) by means of 27-channel EGG recordings are briefly described. The methods are applied to short-bowel syndrome (SBS). The gastro-intestinal tract is traced by videofluorograms after X-ray-opaque barium has been ingested. The MPFs are generally located on the trace of the gastrointestinal tract. The gastric area is occupied by 3 cycles min−1 (up to 28% of total MPFs) and 6 cycles min−1 MPFs (26%). The trace of the small intestine is occupied mainly by 8 cycles min−1 (39%) and 10 cycles min−1 (43%) MPFs. The trace of the colon is occupied almost evenly by all five spectral frequency groups, that is, by 1 (58%), 3 (53%), 6 (48%), 8 (57%) and 10 cycles min−1 (42%). Most interestingly, the numbers of 8–10 cycles min−1 power foci found on EGG maps (including MPFs and relatively higher power foci) are proportional to the remaining length at operation and to the length of the remaining small intestine in the long-term, over 6 years post-operatively. It is therefore possible to follow approximately the trace of the gasterointestinal tract.

Osmolality- and angiotensin-induced responses in the AV3V neurons are affected by estrogen in the ovariectomized rat

The effect of hyperosmolality (300, 320 mosmol/kg H2O) and angiotensin II (A II, 10(-8) and 10(-6) M) was tested on a total of 64 neurons within the periventricular part of the anteroventral third ventricle (AV3V) region in brain slice preparations obtained from ovariectomized (OVX) rats with or without chronic treatment of estradiol-17 beta (E2). Hypertonic perfusion with a 320 mosmol/kg H2O but not a 300 mosmol/kg H2O medium caused a significant increase in the firing discharge rate in OVX animals. Perfusion with either hypertonic medium had no effect in E2-treated rats. The neuronal firing discharge rate of neurons in OVX rats was increased following perfusion with 10(-6) M A II, but not affected following perfusion with 10(-8) M A II. In E2-treated rats, perfusion with neither 10(-8) nor 10(-6) M A II had any effect. These data suggest a dynamic relationship between the ovarian endocrine function and the central mechanisms regulating dipsogenic behavior and/or release of vasopressin in the female rat.

Electrogastrography in patients after operative repair of gastric rupture

Electrogastrography (EGG) measures the myoelectric and motor activity of the stomach as detected by cutaneous electrodes attached to the epigastrium. The specific frequency of gastric activity is thought to be 3 cycles per minute (cpm) as determined by spectral analysis. EGG was performed to evaluate gastric motor function in 13 patients (mean age 11.6 ± 2.90 years) who had undergone operative repair of a gastric rupture. The EGG results were compared with those of 8 normal, age-matched controls (mean age 9.25 ± 2.14 years). The mean frequency (MSF) (2.84 ± 0.067 cpm) of the postprandial EGG spectra of 5 patients with ruptures at or along the greater curvature was significantly lower (P <0.05) than that of the control subjects (3.18 ± 0.0186 cpm). Similarly, the MSF for 3 patients whose areas of rupture were greater than 20 cm2 was 2.75 ± 0.202 cpm in the fasting state (F) and 2.53 ± 0.0385 cpm in the postprandial state (P). These values were significantly lower than those of normal controls (3.29 ± 0.0313 cpm, n = 7 [F]; 3.18 ± 0.0186 cpm, n = 8 [P], respectively). The ratio of fasting to postprandial power was similar between the gastric rupture group and the controls. There was significantly greater variability in the postprandial spectral frequency of the gastric component in the gastric rupture group than in the controls. The results of EGG analysis suggest that the gastric pacemaker and/or gastric motor activity may be disrupted in patients following operative repair of a gastric rupture, although these patients remain asymptomatic.

Conduction velocity of motor nerve and cervical sympathetic and vagus nerve in streptozotocin diabetic rats

We investigated the conduction velocity of motor and autonomic nerves, motor nerve to foot interosseous muscle and cervical vagus and sympathetic nerve, in streptozotocin diabetic rats (1-3 months duration of diabetes) and compared it with that of age-matched controls. In diabetic rats, the motor nerve conduction velocity was significantly reduced but the conduction velocity of cervical vagus and sympathetic nerves was not reduced.