Acid Perfusion Research Articles

Acid Reflux Test for Gastroesophageal Reflux After Distal Gastrectomy: Diagnosis and Clinical Effect of Cisapride

Gastroesophageal reflux (GER) and reflux esophagitis (RE) are common complications after gastrectomy. Reflux of the gastroduodenal contents into the esophagus elicits the same set of symptoms: heartburn, regurgitation, and anterior chest pain. It has been recognized that not all patients with RE have symptoms of reflux and not all patients with reflux symptoms have RE. 1-3 The diagnostic modalities used to evaluate GER include barium study, 4 endoscopy, 5 ambulatory pH monitoring, 6 and acid perfusion, 7 acid reflux, 8 and acid clearance 9 testing. After gastrectomy, however, the postoperative gastric pH is closer to the esophageal or intestinal pH because gastric secretion is decreased. Also, some patients with some reflux symptoms may not be diagnosed by endoscopic examination because no mucosal changes are observed in the esophagus. Diagnostic testing is necessary to determine whether GER is present in a patient who underwent gastrectomy. In this study we compared the acid reflux test with the acid clearance test, barium esophagram, and endoscopy for diagnosis of GER and RE in patients after gastrectomy and to select patients for medical therapy. METHODS Patients. This study included 46 consecutive patients who had undergone Billroth I reconstruction (16 men and 10 women, aged 38‐71 years) or Billroth II reconstruction (15 men and 5 women, aged 39‐74 years) after partial gastrectomy with lymph node resection and truncal vagotomy for gastric cancer. All patients provided informed consent. They all had been outpatients for longer than 4 months (postoperative average, 15 months). Patients showing any evidence of cancer recurrence or stenosis of anastomosis were not included in this study. All patients had undergone preoperative 24-hour esophageal

The effects of acid perfusion of the esophagus on ventilation and respiratory sensation.

The relationship between gastroesophageal reflux (GER) and asthma remains controversial. Asthma symptoms worsen with GER, but are not consistently related to changes in lung function. The purpose of this study was to determine whether acid perfusion (AP) of the esophagus alters ventilation and causes respiratory symptoms. Nonasthmatic patients with normal lung function and esophageal disease (16 females and nine males, FEV1 %predicted = 99+/-9.6), underwent a Bernstein test after motility testing. Airflow, rib cage (Vrc), and abdominal (Vab) tidal volumes, esophageal (Pes) and gastric (Pga) pressure, and surface (Es) and esophageal (Edi) diaphragm electromyographic (EMG) signals were measured. Throat, swallowing, chest, and stomach discomfort and respiratory sensation were estimated with the Borg scale. Minute ventilation (VE) increased during AP and declined during recovery with saline perfusion of the esophagus (7.1+/-1.5 to 8.5+/-2.4 to 7.3+/-2.1 L/min; n = 25; p = 0.0002). Respiratory rate (RR) went from 13.6+/-2.6 to 15.8+/-3.4 to 15.3+/-3.1 breaths/min (n = 25; p = 0.0002) during AP. VE was greater in the Bernstein-positive patients during AP. Tidal volume (VT), Vrc, Vab, Pes, Pga, Es, and Edi did not change during AP. Chest discomfort (D) correlated with ventilation (VE = 0.7 + 0.8 D; r = 0.67; p < 0.001) and respiratory effort sensation (B) (B = 0.2 + 0.4 VE; r = 0.70; p < 0.001) during AP. AP did not inhibit diaphragm activity. Increased VE may explain the paradox of GER worsening respiratory symptoms without changing lung function.

Monitoring and management of acidosis in calf diarrhoea.

Neonatal diarrhoea is a major cause of morbidity and mortality in calves during the first three weeks of life, resulting in considerable economic loss. Aetiological agents include enterotoxigenic Escherichia coli, Salmonella spp, rotavirus, coronavirus and Cryptosporidium parvum, mixed infection being common1-3. As in other species, the cardinal biochemical features of calf diarrhoea are hypovolaemia, hyponatraemia, pre-renal failure and metabolic acidosis-8. There is no relationship between severity of dehydration and acidosis7. In previous studies7'8, acidosis was found to be widespread and severe amongst diarrhoeic suckler calves, and collapsed calves requiring intravenous fluid therapy (IF) were more severely acidotic than those manageable by oral fluid therapy. Calves less than 6 days old were less acidotic than older calves (Figure 1). Recording similar observations, Naylor4 postulated that the age-related difference in severity of acidosis might be explained in terms of susceptibilities to enteric pathogens: the younger calf is likely to be affected by enterotoxigenic E. coil, with consequent rapid dehydration, reduced tissue perfusion and production of lactic acid by the tissues together with intestinal loss of bicarbonate, whereas the older calf is more

Intraduodenal fat alters perceptual and autonomic responses to acid perfusion of the esophagus in GERD patients

Intraduodenal fat alters perceptual and autonomic responses to acid perfusion of the esophagus in GERD patients

Intraluminal acid perfusion causes esophageal shortening in humans: A contributing factor in the etiology of hiatial hernia (HH)?

Intraluminal acid perfusion causes esophageal shortening in humans: A contributing factor in the etiology of hiatial hernia (HH)?

Role of mast cell-derived mediators in acid-induced shortening of the esophagus

It has recently been demonstrated that acid-induced esophageal mucosal injury leads to esophageal shortening, raising the possibility that reflux esophagitis per se may contribute to the development of hiatal hernia. The aim of the present study was to determine whether mast cell-derived mediators are involved in this acid-induced esophageal shortening. Changes in esophageal length were continuously monitored in anesthetized opossums while the esophageal lumen was perfused with 100 mmol/l HCl or normal saline. Changes in esophageal length were compared between animals perfused with acid, with or without pretreatment with the mast cell stabilizers doxantrazole or disodium cromoglycate (DSCG), and animals perfused with normal saline, with or without pretreatment with DSCG. In separate in vitro studies the effect of the mast cell stabilizers on electrical field stimulation-induced esophageal longitudinal muscle contraction was determined. Gradual esophageal lengthening occurred during saline perfusion, irrespective of whether animals were pretreated with DSCG. In contrast, acid perfusion induced esophageal shortening, which was abolished by pretreatment with either doxantrazole or DSCG in doses sufficient to attenuate the acid-induced mucosal histamine release. In vitro, the mast cell stabilizers had no effect on electrical field stimulation-induced esophageal shortening. This study suggests that esophageal shortening associated with acute acid-induced esophageal mucosal injury in the opossum is dependent on mast cell-derived mediators.

Effect of preinduction of heat-shock proteins on acetic acid-induced small intestinal lesions in rats.

Bowel dysfunction such as irritable bowel syndrome caused by stress is well described. Previous reports suggest that stress is known to cause the release of endogenous substances such as catecholamine, beta-endorphine, 5-hydroxytryptamine, corticotropin-releasing factor, and thyrotropin-releasing hormone (TRH). However, the role played by these neurohormonal mediators in bowel dysfunction under stress conditions is not well known. We investigated the influence of water-immersion stress or TRH administration on the expression of 60-kDa, 72-kDa, and 90-kDa heat-shock proteins (HSP60, HSP72, and HSP90, respectively) in rat small intestinal mucosa by Western blot and immunohistochemical analyses. The cytoprotective function of preinduced HSPs on experimentally induced mucosal damage also was studied. In order to investigate the influence of preinduction of HSP60 on small intestinal damage, the small intestinal lumen was perfused with 1.5% acetic acid 1 ml/min for 15 min with or without pretreatment with water-immersion stress or TRH administration. Expression of HSP60 was significantly increased by water-immersion stress or TRH administration in the small intestinal mucosa, whereas HSP72 and HSP90 did not increase. Interestingly, expression of this protein showed the biphasic peak pattern after water-immersion stress or TRH administration. Each peak was observed 3-6 hr and 21-24 hr after the initiation of water-immersion stress or TRH administration. Immunohistochemical study also showed a significant increment of HSP60 in both the cytoplasm and nuclei of the small intestinal mucosal cells. No histopathologic alteration was observed in rat small intestinal mucosa after each treatment. Small intestinal damage caused by 1.5% acetic acid perfusion was not influenced by preinduction of HSP60. We demonstrated that water-immersion stress or TRH administration specifically induced HSP60, although preinduction of this protein did not show a cytoprotective function in the small intestinal mucosa.

Gastroesophageal reflux disease is a common cause of noncardiac chest pain in a country with a low prevalence of reflux esophagitis.

Gastroesophageal reflux disease is believed to be uncommon in the East. This study aimed to determine if such a condition was a significant cause of noncardiac chest pain in Singapore. Eighty consecutive patients with recurrent chest pain, who had cardiac and other obvious causes excluded, underwent esophagogastroduodenoscopy, standard manometry, acid perfusion test, and prolonged ambulatory pH and pressure monitoring. Endoscopic esophagitis, positive acid perfusion tests, pathologic reflux, and positive chest pain-reflux correlation were detected in 7/80 (8.8%), 11/70 (15.7%), 14/61 (23.0%), and 12/25 (48.0%) patients, respectively. Among those with pathologic reflux, endoscopic esophagitis was present in only two (14.3%). Overall, 32 (40%) patients had gastroesophageal reflux disease. Esophageal motility disorder, alone or in association with gastroesophageal reflux disease, was demonstrated in only five (6.3%) patients. Our results confirmed western reports that gastroesophageal reflux disease was a common cause of noncardiac chest pain, whereas motility disorder was an infrequent cause of such pain.

GASTROESOPHAGEAL REFLUX AND ASTHMA IN THE ELDERLY PATIENT: Pathogenesis, Diagnosis, and Treatment

The prevalence of gastroesophageal reflux (GER) in the elderly population may be as high as 20%. There is little information, however, about elderly patients with GER-associated asthma. The exact relationship between GER and asthma is unclear, although the association is well recognized. This article reviews the data that link GER to clinical presentations, diagnostic tools, and treatment options.

Effect of endotoxin and platelet-activating factor on lipid oxidation in the rat heart.

The effects of endotoxin and platelet-activating factor (PAF) administered in vivo and in vitro on lipid oxidation by isolated perfused working rat heart were investigated and compared. Endotoxin administered in vivo decreased oleate oxidation in perfused hearts and caused increased accumulation of lipid in myocardial tissue; this was accompanied by a dose-dependent inhibition of cardiac mechanical function. There was no effect on triolein (chylomicron) oxidation. By contrast, PAF administered in vivo caused a small (non-significant) increase in the oxidation rate of oleate and triolein, and also increased myocardial lipoprotein lipase activity. Cardiac mechanical function was not inhibited by PAF-indeed pretreatment of animals by PAF administered in vivo protected the heart from the decline in function associated with subsequent fatty acid perfusion. Administration of endotoxin during perfusion in vitro did not affect oleate or triolein oxidation and cardiac mechanical function was unchanged; PAF administered in vitro caused an early increase in oleate oxidation and a later increase in triolein oxidation. Administration of both endotoxin and PAF in vitro increased myocardial lipoprotein lipase activity. PAF is unlikely to be responsible for all of the effects of endotoxin on cardiac lipid metabolism.

Altered postprandial motility in chronic pancreatitis: Role of malabsorption

BACKGROUND & AIMS: Intraileal nutrients modulate gastrointestinal motility, but effects of maldigestion on postprandial motility are unknown. The aim of this study was to compare motor responses with ileal nutrient exposure in health and pancreatic insufficiency after a meal or intraluminal perfusion. METHODS: After oroileal multilumen intubation for duodeno-jejuno-ileal sampling, marker perfusion, and motility recording, 14 normal subjects and 12 patients with severe pancreatic insufficiency received a labeled liquid meal twice, either with placebo or pancreatin. Effects of intraileal nutrient perfusion on fed motility induced by duodenal amino acid perfusion were also investigated. RESULTS: Compared with normals, untreated patients had greater cumulative ileal nutrient delivery (69 +/- 21 vs. 487 +/- 232 kJ), shorter fed pattern (196 +/- 22 vs. 131 +/- 14 minutes), greater 90% gastric emptying (163 +/- 12 vs. 128 +/- 10 minutes), and faster small intestinal transit (86 +/- 9 vs. 44 +/- 6 minutes). Pancreatin reversed these changes. Ileal nutrient perfusion converted fed into interdigestive-like motility in normals (7 of 8) and patients (4 of 5). CONCLUSIONS: In subjects with pancreatic insufficiency, a low-energy liquid meal induces shorter fed motor pattern associated with accelerated gastric emptying and intestinal transit compared with healthy subjects. Because changes responded to enzyme treatment and could be reproduced by ileal nutrient perfusion, ileal delivery of malabsorbed chyme may be involved as a mechanism. (Gastroenterology 1997 May;112(5):1624-34)

A simple immunofluorescence technique for simultaneous visualization of mast cells and nerve fibers reveals selectivity and hair cycle--dependent changes in mast cell--nerve fiber contacts in murine skin.

Close contacts between mast cells (MC) and nerve fibers have previously been demonstrated in normal and inflamed skin by light and electron microscopy. A key step for any study in MC-nerve interactions in situ is to simultaneously visualize both communication partners, preferably with the option of double labelling the nerve fibers. For this purpose, we developed the following triple-staining technique. After paraformaldehyde-picric acid perfusion fixation, cryostat sections of back skin from C57BL/6 mice were incubated with a primary rat monoclonal antibody to substance P (SP), followed by incubation with a secondary goat-anti-rat TRITC-conjugated IgG. A rabbit antiserum to CGRP was then applied, followed by a secondary goat-anti-rabbit FITC-conjugated IgG. MCs were visualized by incubation with AMCA-labelled avidin, or (for a more convenient quantification of close MC-nerve fiber contacts) with a mixture of TRITC- and FITC-labelled avidins. Using this simple, novel covisualization method, we were able to show that MC-nerve associations in mouse skin are, contrary to previous suggestions, highly selective for nerve fiber types, and that these interactions are regulated in a hair cycle-dependent manner: in telogen and early anagen skin, MCs preferentially contacted CGRP-immunoreactive (IR) or SP/CGRP-IR double-labelled nerve fibers. Compared with telogen values, there was a significant increase in the number of close contacts between MCs and tyrosine hydroxylase-IR fibers during late anagen, and between MCs and peptide histidine-methionine-IR and choline acetyl transferase-IR fibers during catagen.

Increased esophageal chemoreceptor sensitivity to acid in patients after successful reversal of Barrett's esophagus.

When compared to patients with erosive esophagitis, patients with Barrett's esophagus have demonstrated reduced chemo- and mechanoreceptor sensitivity to acid infusion and balloon distension, respectively. However, anecdotal clinical experience suggested an increase in symptom perception in patients after successful elimination of Barrett's epithelium, using multipolar electrocoagulation (MPEC) and high-dose proton pump inhibitor (PPI). To determine perception thresholds to acid infusion, we evaluated eight consecutive patients after a series of MPEC treatments resulted in complete elimination of Barrett's mucosa and compared them to 10 age-matched patients with nonreversed Barrett's esophagus and 10 patients with symptomatic, endoscopy-documented erosive esophagitis (Hetzel-Dent grade 2 or greater). Chemosensitivity was determined by a modified acid perfusion test, where acid perception thresholds were quantified by the lag time to initial typical symptom perception, sensory intensity rating, and an acid perfusion sensory score (APSS). While patients after successful elimination of Barrett's esophagus had similar sensory intensity ratings and APSS as patients with erosive esophagitis, the lag times differed significantly between the groups, and both groups had significantly higher sensory intensity ratings and APSS than patients with nonreversed Barrett's esophagus. In conclusion, patients after complete reversal of Barrett's mucosa are unexpectedly as sensitive to acid as symptomatic patients with erosive esophagitis.

NMR Studies of Inorganic Phosphate Compartmentation in the Isolated Rat Liver during Acidic Perfusion

Mitochondrial inorganic phosphate has been shown to be undetectable by31P NMR in the isolated rat liver perfused under physiological conditions. Cold perfusion (4°C) with valinomycin (K+ionophore) induced the appearance of an additional resonance assigned to Pifrom mitochondrial compartment (Pi,mito) (Thiaudièreet al.,1993,FEBS Lett.330, 232–235). Here we have demonstrated that Pi,mitocan be detected by NMR under normothermic conditions (37°C) in acidic (pH 6.5, bicarbonate-free) perfused liver using 50 nmvalinomycin or 10 μmN,N′-dicyclohexylcarbodiimide (DCCD, a mitochondrial H+-ATP synthase inhibitor). These conditions resulted in a significant increase in mitochondrial Picontent. In the presence of valimomycin, pH values of 7.00 ± 0.07 and 6.60 ± 0.10 (n= 7) for mitochondria and cytosol, respectively, were determined from the chemical shift values of Piresonances. Electron microscopy demonstrated a large matrix swelling under valinomycin perfusion, explaining the increased level of mitochondrial Pi. The amount of mitochondrial Pimeasured by NMR increased linearly with the cellular ATP depletion, suggesting a mitochondrial influx of Pifrom the cytosolic compartment with valinomycin perfusion. Moreover, the level of matrix Piwas dependent on the cytosolic pH value, the resonance being not detectable at physiological cytosolic pH. During mitochondrial swelling, Piinflux was likely to be associated with proton influx, owing to the stability of transmembrane pH gradient and matrix proton concentration.

Pharmacologic characteristics of excitatory γ-amino-butyric acid (GABA) receptors in a snail neuron

1. 1. The pharmacologic characteristics of excitatory γ-aminobutyric acid (GABA) receptors, termed muscimol II type GABA receptors, found in a giant neuron type, v-LCDN (ventral-left cerebral distinct neuron), of an African giant snail ( Achatina fulica Férussac), were studied using the mammalian GABA receptor agonists, antagonists and synergists and GABA uptake inhibitor using the voltage clamp technique. 2. 2. GABA and its agonists, ejected by brief pressure, produced an inward current ( I in) of the following order of potency: trans-t-aminocrotonic acid (TACA)>GABA>muscimol>isoguvacine> 5-aminopentanoic acid and cis-4-aminocrotonic acid (CACA). (±)-Baclofen and 3-aminopropylphosphonic acid (APPA) were ineffective. The I in values produced by GABA, TACA, isoguvacine and CACA were stable for at least 60 min, whereas the I in induced by muscimol was not. 3. 3. According to the dose-response curves of GABA, TACA, isoguvacine and CACA, measured by the varied pressure duration method, the ED 50 value of CACA was larger than those of the other compounds, and E max of TACA was larger than that of GABA, whereas E max values of isoguvacine and CACA were smaller. 4. 4. The perfusion of β-alanine, pentobarbital and 5-aminopentanoic acid inhibited the I in induced by GABA, whereas (-)-bicuculline, pitrazepin, diazepam and 2-hydroxysaclofen had no effect. 5. 5. From the effects of β-alanine on the dose-response curves of GABA, measured by the varied pressure duration method, β-alanine competitively inhibited the I in caused by GABA. According to the effects of pentobarbital on the dose-response curves of GABA, this drug noncompetitively inhibited the I in using the varied pressure duration method, and partly competitively and partly noncompetitively using the Y-tube method. The effects of 5-aminopentanoic acid on the dose-response curves of GABA indicated that this drug noncompetitively inhibited the I in using the varied pressure duration method, and partly noncompetitively and partly uncompetitively using the Y-tube method. 6. 6. The pharmacologic features of the Achatina muscimol II type GABA receptors were similar to those of mammalian GABA C (GABA pl) receptors, except for the effects of pentobarbital.

Intraduodenal free fatty acids rather than triglycerides are responsible for the release of CCK in humans.

Exocrine pancreas from different species behaves differently in response to the presence of intact or digested nutrients in the duodenum. A failure of cholecystokinin (CCK) release after a meal has been shown among patients with exocrine pancreatic insufficiency. This abnormality could be restored by the administration of pancreatic extracts, suggesting that digested rather than intact nutrients are responsible for the release of CCK and subsequently gallbladder contraction in humans. The aim of this study was to determine the specific role of different lipidic stimuli in humans. Seven male patients (mean age, 52 years) with pancreatic insufficiency secondary to chronic pancreatitis were selected. Pancreatic insufficiency was considered severe in five of them (lipase output, < 1,000 IU/min) and moderate in another two (lipase output, > 1,000 and < 2,300 IU/min). Plasma CCK (by bioassay), gallbladder contraction (by ultrasound), and enzyme output (chymotrypsin) in response to duodenal administration of either oleic acid as free fatty acids or 20% Intralipid as triglycerides were measured in each patient with at least a 48-h interval between each test. In all these patients with pancreatic insufficiency, duodenal perfusion of free fatty acids generated a more pronounced (91 +/- 11 vs. 49 +/- 21 pM) and faster (15 vs. 30 min) (p < 0.05) CCK release than triglycerides. Furthermore, gallbladder contraction was more efficient when free fatty acids instead of triglycerides were administered in the duodenum (86 +/- 5 vs. 69 +/- 4%) at 10 min (p < 0.05) and (73 +/- 8 vs. 51 +/- 5%) at 15 min (p < 0.03). Among patients with measurable residual pancreatic function, enzyme outputs were shown to be higher during free fatty acid than triglyceride perfusion. In humans, free fatty acids rather than triglycerides, when present in the duodenum, stimulate CCK release and gallbladder contraction. In patients with moderate pancreatic insufficiency this phenomenon may increase residual enzymatic secretion. These results allow us to encourage the development of enzymatic preparations as acid-resistant lipases that cause a fast release of free fatty acids in the duodenum.

Oxidant generation with K +-induced depolarization in the isolated perfused lung

This study evaluated whether cell membrane depolarization can induce oxidant generation in the isolated perfused rat lung as has been demonstrated with bovine pulmonary artery endothelial cells. Depolarization was produced by perfusing the lungs with high [K +] or with glyburide and was evaluated with bis-oxonol lung surface fluorometry. Lung surface bis-oxonol fluorescence increased above baseline (at 5.9 mM K +) by 18.5% with 24 mM K +, 35% with 48 mM K +, and 67% with 96 mM K +, indicating graded membrane depolarization, and by 75% during perfusion with 10 μM glyburide. Oxidant generation was evaluated with hydroethidine lung surface fluorometry, and with assay of tissue thiobarbituric acid reactive substance (TBARS), conjugated dienes, and perfusate H 2O 2. Depolarization by high K + or glyburide led to significant increases in generation of tissue oxidants and lipid peroxidation. Bodipy-FL-glyburide microfluorography showed localization of glyburide binding primarily to vascular endothelial cells vascular and airway smooth muscle cells, alveolar type II cells, and to nonciliated cells of the airway epithelium. These results indicate that cellular depolarization is associated with oxidant generation by the lung and suggests a role for K +-channels in these events. © 1997 Elsevier Science Inc.

Action of 5-hydroxytryptamine in facilitating N-methyl-D-aspartate depolarization of cortical neurones mimicked by calcimycin, cyclopiazonic acid and thapsigargin.

1. The ability of calcimycin, cyclopiazonic acid and thapsigargin to facilitate the N-methyl-D-aspartate (NMDA)-mediated depolarization of cortical projection neurones was investigated by use of grease-gap recording and the results compared with the facilitation that results from activation of 5-hydroxytryptamine2A receptors. 2. Calcimycin (0.25 to 3 microM), cyclopiazonic acid (5 to 30 microM), and thapsigargin (10 to 300 nM) reversibly facilitated the NMDA (50 microM)-induced depolarization in the presence of tetrodotoxin. The concentration-response relationships were bell-shaped with a mean enhancement of 550% for calcimycin (1 microM) and approximately 400% for cyclopiazonic acid (20 microM) and thapsigargin (100 nM). At the highest concentration of each agent tested, no facilitation was observed. 3. Chlorpromazine (1 microM) partially restored a facilitation at 3 microM calcimycin and 300 nM thapsigargin. Myo-inositol (10 mM) and 100 nM staurosporine were both ineffective in this regard. 4. The depolarization elicited by 10 microM quisqualate or 5 microM kainate was not facilitated by 10 microM cyclopiazonic acid. 5. Calcimycin (0.5 microM), cyclopiazonic acid (20 microM), and thapsigargin (100 nM) elicited a significant facilitation in the presence of an antagonist cocktail consisting of D,L-2-amino-3-phosphonopropionic acid, prazosin, ritanserin, and scopolamine, although the magnitude of the facilitation was reduced. 6. Facilitation of the NMDA depolarization elicited by both 30 microM 5-hydroxytryptamine and 10 microM phenylephrine was eliminated in nominally Mg(2+)-free medium. In contrast, the facilitation induced by 0.5 microM calcimycin remained intact. 7. Bis-(o-aminophenoxy)-ethane-N,N,N,N, tetraacetic acid aminoethoxy (50 microM) or perfusion with nominally Ca(2+)-free medium eliminated facilitation of the NMDA depolarization induced by 30 microM 5-hydroxytryptamine and 100 nM thapsigargin. 8. The facilitation induced by both 30 microM 5-hydroxytryptamine and 1 microM calcimycin was reduced in a concentration-dependent manner by nifedipine (1 to 10 microM). 9. Calcimycin, cyclopiazonic acid and thapsigargin facilitate the NMDA depolarization in a manner which closely mimics the facilitation induced by 5-hydroxytryptamine. It is concluded that enhancement of the NMDA depolarization at cortical projection neurones results from an elevation of Ca2+ in the cytosol and that several sources of Ca2+ contribute to the facilitation.

Blood-endothelial cell and blood-brain transport of L-proline, alpha-aminoisobutyric acid, and L-alanine.

We report the application of multiple time regression analysis with the in situ brain perfusion technique to measure the rates of passage between blood and brain for [14C] L-proline, [14C] L-alanine, and [14C] alpha-aminoisobutyric acid (AIB) and their rapidly reversible volumes following perfusion of these amino acids from 10 to 60 seconds. We also report on their mechanism of transport. Proline diffused through the blood-brain barrier with a transfer coefficient (Kin) of 0.55 +/- 0.15 x 10(-4) ml/s/g and had no reversible compartment. AIB had a low Kin of 0.68 +/- 0.14 x 10(-4) ml/s/g and a significant reversible volume of 4.34 +/- 0.51 x 10(-3) ml/g in parietal cortex. L-alanine had the highest transfer coefficient, 3.11 +/- 0.26 x 10(-4) ml/s/g, and a reversible volume of 10.03 +/- 0.93 x 10(-3) ml/g in the same cerebral region. Postwash procedures which remove any radiotracer in the vasculature and capillary depletion were performed for alanine and AIB, as they had significant reversible compartments, to test the possibility of rapid efflux from the endothelial cells. Results obtained from wash and capillary depletion procedures suggest that a rapid efflux could occur from endothelial cells after entry of alanine and AIB. Mechanisms of transport for L-alanine and AIB were investigated using amino acids (5 mM) as substrates and inhibitors of different amino acid transport systems. AIB transport was reduced by plasma and L-leucine and unchanged by sodium-free buffer, confirming its passage by the L1 system. L-alanine uptake was sodium-independent and not reduced by plasma. L-serine, L-cysteine, L-leucine and L-phenylalanine produced similar inhibition (66%) while L-alanine produced a lower inhibition (41%). L-arginine increased alanine uptake in cortex and thalamus. Adding L-serine to L-phenylalanine reduced the uptake only in cortex and hippocampus. These data suggest that L-alanine is transported by another L transport system different from the L1 system at the luminal membrane.

Kainic Acid-Induced Focal Cortical Seizure Is Associated with an Increase of Synaptophysin Immunoreactivity in the Cortex

Aberrant neural sprouting of mossy fiber terminals in the supragranular layer of dentate gyrus is consistently observed following seizures in an animal model of epilepsy. It is also observed in hippocampi taken from epileptic patients with hippocampal sclerosis. The aberrant neural sprouting with synaptic reorganization is one of the proposed cellular mechanisms underlying epileptogenesis. It is not known whether aberrant synaptogenesis can be induced in the cortex, as in hippocampus, by seizure activity. In this study, synaptic terminals in the cortex were measured after focal cortical seizures by a semiquantitative image analysis of synaptophysin immunoreactivity. Brief intracortical perfusion of kainic acid induced focal status epilepticus and destructive cortical lesions. Synaptophysin immunoreactivity was significantly increased in the area where kainic acid was perfused. The increase of synaptophysin immunoreactivity, indicating an increase of synaptogenesis, was observed at 2 and 4 weeks after focal cortical seizures. This result suggests that kainic acid-induced seizure activity is associated with long-lasting synaptogenesis in the cortex. Studies centering on the physiological consequences of aberrant synaptogenesis may lead to additional understanding of the mechanisms underlying cortical epileptogenesis.