Biomedical subjects

C H Malbert

Publications and source records attributed to C H Malbert.

At least 19 recordsLinked to original sources

PubMed2005

Involvement of NO in gastric emptying of semi-solid meal in conscious pigs.

The influence of non-selective nitric oxide synthase (NOS) inhibition on gastric emptying of a semi-solid meal was studied in conscious pigs. Antroduodenal motility and fundic compliance were also assessed to evaluate the mechanisms at the origin of potential alteration in gastric emptying pattern. N(G)-nitro-L-arginine methyl ester (L-NAME; 20 mg kg(-1) i.v.) delayed gastric emptying (half-emptying time of 128.98 +/- 16.86 min vs 73.74 +/- 7.73 min after saline, P < 0.05, n = 6) as a result of decreased proximal gastric emptying. No changes were observed for distal gastric emptying as a result of unchanged antral motility. Similarly, no changes were noted on duodenal motor patterns either in the fasted or in the fed state. L-NAME decreased fundic compliance in fasted state (49 +/- 11 mL mmHg(-1) vs 118 +/- 15 mL mmHg(-1) after saline, P < 0.05, n = 6). As this phenomenon is expected to increase emptying rate, the gastroparesis induced by NOS inhibition is thus likely to originate from distal resistive forces. It is concluded that NO positively modulates gastric emptying.

Animals↗

PubMed2002

Antropyloroduodenal, cholecystokinin and feeding responses to pulsatile and non-pulsatile intraduodenal lipid infusion.

The contribution of the pulsatile nature of gastric emptying to small intestinal feedback mechanisms modulating antropyloroduodenal motility and appetite is unknown. On separate days, eight healthy male volunteers (18-34 years) received randomized, single-blind, intraduodenal (ID) infusions of 10% Intralipid (2 kcal min(-1)), either continuously [CID], or in a pulsatile manner [PID] (5 s on/15 s off) and 0.9% saline (control) administered continuously, each at a rate of 1.8 mL min(-1) for 3 h. During each infusion, subjective ratings of appetite were assessed and antropyloroduodenal pressures recorded with a 16-lumen manometric assembly incorporating a pyloric sleeve sensor. Plasma cholecystokinin was measured from blood collected at regular intervals throughout the infusion. At the end of each infusion the manometric assembly was removed, subjects were offered a buffet meal and the energy and macronutrient content of the meal was measured. Both ID lipid infusions stimulated isolated pyloric pressure waves (IPPWs) (P < 0.001) and basal pyloric pressure (P < 0.01) and suppressed antral (P < 0.05) and duodenal (P < 0.05) pressure waves when compared to controls; there was no difference in the effects of CID and PID lipid on antropyloroduodenal pressures. Infusions of lipid significantly increased plasma CCK concentrations (P < 0.05) compared with saline, but concentrations were not different between the two modes of lipid delivery (P > 0.05, CID vs. PID). Both intraduodenal lipid infusions decreased hunger (P < 0.05), increased fullness (P < 0.05) and reduced energy intake (P < 0.05) when compared with controls; again there was no difference between CID and PID lipid. We conclude that at the infusion rate of similar 2 kcal min(-1), the acute effects of intraduodenal lipid on antropyloroduodenal pressures, plasma CCK concentration and appetite are not modified by a pulsatile mode of lipid delivery into the duodenum.

Adolescent↗

PubMed2002

Human duodenal phase III migrating motor complex activity is predominantly antegrade, as revealed by high-resolution manometry and colour pressure plots.

Abstract Late phase III migrating motor complex activity has been said to be primarily retroperistaltic but has not been assessed with high resolution manometry or three-dimensional colour pressure plots (pressure/time/distance). Duodenal phase III was examined in healthy young volunteers (seven male, two female) with a 20-lumen assembly. With the most proximal sidehole in the distal antrum, after a 4.5-cm interval 18 sideholes at 1.5-cm intervals spanned the duodenum with a final sidehole 3 cm beyond. Fasting pressures were recorded until phase III occurred. Comparisons were made between proximal (P) and distal (D) duodenum during early (E) (first 0.5-1 min) and late (L) (last 0.5-1 min) phase III. With colour pressure analysis, 121 of 180 pressure wave (PW) sequences were purely antegrade, two purely retrograde and 57 bidirectional. Ten of fifty-seven bidirectional PW sequences were complex, branching to become two separate sequences. Bidirectional sequences occurred more frequently in late than early phase III (L 43 vs. E 14 of 57), but their occurrence did not differ between proximal and distal duodenum (P31 vs. D 24 of 57). Antegrade propagation velocity was faster in late compared with early phase III (L 28.50 vs. E 17.05 mm s(-1); P = 0.006), but did not differ between proximal and distal duodenum. Colour pressure analysis also indicated an intermittent segmental pattern to phase III, with each subject exhibiting a change in velocity or direction, or a relative failure of peristalsis somewhere along the duodenum during part of phase III. Duodenal phase III is not homogenous and, in contrast with previous studies, does not primarily constitute a retroperistaltic pump. Colour pressure analysis is useful in interpreting intraluminal pressure profiles and may improve the sensitivity and specificity of clinical studies.

Adult↗

PubMed2001

Role of vagal innervation on intragastric distribution and emptying of liquid and semisolid meals in conscious pigs.

The role of vagal innervation on emptying patterns and intragastric distributions of liquid and semisolid meals is still controversial. We aimed to record these features after dorsal, ventral and truncal vagotomies, using external gamma scintigraphy in conscious pigs in which the dorsal vagus specifically innervates the proximal stomach. Imaging of the stomach was performed for all experimental situations and before surgery using 99mTc-labelled glucose and porridge meals. Emptying of liquids was faster after dorsal vagotomy, whereas it was unchanged after ventral and truncal vagotomies (T1/2 = 57 +/- 8.5, 31 +/- 14.4, 54 +/- 9.1 and 42 +/- 14.9 min for intact, dorsal, ventral and truncal vagotomies, respectively). On the other hand, truncal vagotomy significantly reduced the emptying rate of semisolids whereas dorsal and ventral vagotomies had no significant effect (T1/2 = 96 +/- 7.2, 113 +/- 8.1, 75 +/- 9.9 and 260 +/- 56.6 min for intact, dorsal, ventral and truncal vagotomies). Morphological analysis of the gastric shape confirmed an overdistended proximal stomach after truncal vagotomy only. For semisolids, proximal stomach emptying followed the same emptying pattern as the entire stomach, irrespective of the surgical procedure. We concluded that the proximal stomach is the main control for the emptying of liquids and semisolids. The vagal control of overall gastric emptying for semisolids is probably identical to that modulating the intragastric distribution of the meal.

Animals↗

PubMed2001

Changes in intragastric meal distribution are better predictors of gastric emptying rate in conscious pigs than are meal viscosity or dietary fibre concentration.

The effect of dietary fibre on the gastric emptying rate of solids is controversial. Similarly, the mechanisms by which it modulates food intake are partially unknown. Gastric emptying and proximal v. distal stomach filling were evaluated in triplicate on four conscious pigs using scintigraphic imaging. Each animal received in an isoenergetic manner a concentrate low-fibre diet enriched in starch (S) and two high-fibre diets based on sugar beet pulp (BP) or wheat bran (WB). All meals had the same viscosity before ingestion (100.0-100.5 Pa.s). Viscosity of the gastric contents was measured in four additional animals fitted with a gastric cannula. The gastric emptying rate of BP diet was significantly slower than S and WB diets (t1/2 78.4 (sem 5.68), 62.8 (sem 10.01) and 111.6 (sem 10.82) min for S, WB and BP diets respectively, P<0.05). For BP diet only, rate of distal stomach filling was steady during the first 120 min after the meal whereas that of S and WB diets decreased in an exponential manner. Numerous backflow episodes from the distal into the proximal stomach were observed for BP diet that generated the larger intragastric viscosity (0.26 (sem 0.03), 0.3 (sem 0.02) and 0.52 (sem 0.002) Pa.s for S, WB and BP respectively). In conclusion, viscosity of the meal or the percentage total fibre, unlike viscosity of the gastric contents, are poor predictors for emptying. The reduced emptying rate observed with BP is associated with major changes in intragastric distribution of the meal absent with WB and S diets.

Animal Feed↗

PubMed2001

The vagus is inhibitory of insulin secretion under fasting conditions.

The involvement of the vagus in the insulin response during the early phase of absorption of a meal has been demonstrated recently. The extent of this vagal influence was investigated during fasting in an anesthetized porcine model. Portal and systemic insulin were evaluated together with glycemia during cooling and sectioning of both cervical vagal trunks in 12 splanchnicotomized or sham-operated pigs. In sham-operated animals, portal and systemic insulin were significantly and reversibly increased by cooling (173 and 123%, respectively). Portal insulin peaked 20 min after the onset of cooling but declined slowly while cooling was still activated. In contrast, systemic insulin was increased evenly along cooling. Section of the vagus was also associated with a portal and systemic insulin increase (144 and 117%) but to a lesser extent than cooling. In both treatments, portal and systemic insulin increases were either reduced (vagal cooling) or eliminated (vagal section) in splanchnicotomized animals. We conclude that the vagus exerts an inhibitory activity on interdigestive insulin secretion that is partly mediated by the splanchnic nerves.

Analysis of Variance↗

PubMed2001

Nutrient-induced spatial patterning of human duodenal motor function.

The spatiotemporal patterning of duodenal motor function has been evaluated comprehensively for the first time in humans, with a novel 21-lumen manometric assembly. In nine young, healthy volunteers (6 male, 3 female), duodenal motility was recorded during fasting and three 45-min intraduodenal (ID) nutrient infusion periods (Intralipid at 0.25, 0.5, and 1.5 kcal/min). Pressures were recorded along the length of the duodenum with an array of 18 sideholes at 1.5-cm intervals. Pressure patterns were compared for the final 20 min of each of the four periods. Compared with fasting, ID lipid was associated with regional variation in pressure wave (PW) sequences, with fewer proximally and more distally; this was not observed during fasting (P < 0.001). During fasting and all rates of lipid infusion, most (87-90%) PW sequences were short (1.5-4.5 cm), with a small number (2-4%) of 10.5 cm or longer. At all times, antegrade PW sequences occurred more frequently than retrograde sequences over all distances examined (3, 4.5, and >6 cm), and the proportion of antegrade sequences increased with greater PW sequence length (P = 0.0001). Increasing ID lipid rates appeared to produce dose-related suppression of PW sequences (P < 0.001). The frequency and spatial patterning of human duodenal motor function show substantial variability in response to different nutrient delivery rates. These complex patterns are likely to be involved in duodenal modulation of flow and gastric emptying rate.

Adult↗

PubMed2001

Desensitization of ileal vagal receptors by short-chain fatty acids in pigs.

Coloileal reflux episodes trigger specialized ileal motor activities and inhibit gastric motility in pigs. The initiation of these events requires the detection by the distal ileum of the invading colonic contents that differ from the ileal chyme primarily in short-chain fatty acid (SCFA) concentrations. In addition to the already described humoral pathway, this detection might also involve ileal vagal afferents. Sensitivity to SCFA of 12 ileal vagal units was investigated in anesthetized pigs with single-unit recording at the left cervical vagus. SCFA mixtures (0.35, 0.7, and 1.4 mol/l) containing acetic, propionic, and butyric acids in proportions identical to that in the porcine cecocolon were compared with isotonic and hypertonic saline. All units behaved as slowly adapting mechanoreceptors (half-adaptation time = 35.4 +/- 15.89 s), and their sensitivity to local mechanical probing was suppressed by local anesthesia; 7 units significantly decreased their spontaneous firing with 0.7 and 1.4 but not 0.35 mol/l SCFA infusion compared with hypertonic or isotonic saline. Similarly, the response induced by distension in the same seven units was reduced (5 neurons) or abolished (2 neurons) after infusion of 0.7 (22.8 +/- 2.39 impulses/s) and 1.4 (30.3 +/- 2.12 impulses/s) mol/l SCFA solutions compared with isotonic saline (38.6 +/- 4.09 impulses/s). These differences in discharge were not the result of changes in ileal compliance, which remained constant after SCFA. In conclusion, SCFA, at concentrations near those found during coloileal reflux episodes, reduced or abolished mechanical sensitivity of ileal vagal afferents.

Acetic Acid↗

PubMed2000

Metabolic acidosis and respiratory acidosis impair gastro-pyloric motility in anesthetized pigs.

UNLABELLED: Acidosis impairs smooth muscle function in various organs. However, the effects of acidosis on the gastroduodenal tract are unknown while its dysfunction has potential perioperative harmful consequences. We investigated the effects of metabolic (MA) and respiratory acidosis (RA) on upper gut motility in tracheally ventilated pigs whose anesthesia was induced with halothane and maintained with alpha-chloralose-urethane administration (IV). Increased dead space and perfusion of hydrochloric acid 1 N (150 mL over 30 min) were used to induce RA and MA, respectively. Measurements of fundic tone using an electronic barostat, antro-pyloroduodenal phasic motility with perfused manometry and antro-duodenal electric control activity by electromyography were used to evaluate gastroduodenal function. Acidosis increased the fundic tone as reflected by a decrease in barostat volumes from 275+/-83 to 194+/-88 mL for MA and from 278+/-93 to 236+/-106 mL for RA. Pyloric and duodenal basal tones were not affected by either acidosis. A decrease in pyloric contraction amplitude from 95+/-24 to 62+/-26 mm Hg during MA and from 94+/-26 to 64+/-20 mm Hg during RA was observed. Both acidosis altered antral control activity that became dysrhythmic. Acidosis could be implicated in perioperative complications, such as gastroparesis, emesis, and regurgitation of gastric contents. IMPLICATIONS: Metabolic and respiratory acidosis mainly affects gastric antral rhythms and has a major effect on fundic tone. Acidosis could be implicated in perioperative complications, such as gastroparesis, emesis, and regurgitation of gastric contents.

Acidosis↗

PubMed2000

The stimulation of antral motility by erythromycin is attenuated by hyperglycemia.

OBJECTIVE: Diabetic gastroparesis is usually treated with prokinetic drugs, of which the most potent, when given intravenously during euglycemia, is erythromycin. Recent studies have demonstrated that the gastrokinetic effects of erythromycin are attenuated by hyperglycemia. The aim of this study was to determine whether the effects of erythromycin on antropyloroduodenal motility, including the organization of antral pressure waves, are modified by hyperglycemia. METHODS: A total of eight healthy male volunteers (median age 24 yr) were studied on 2 days each in randomized order. A manometric assembly, incorporating six antral, two pyloric, and seven duodenal sideholes and a pyloric sleeve sensor, was positioned with the sleeve spanning the pylorus. The blood glucose concentration was stabilized at about 5 mmol/L (euglycemia) or 15 mmol/L (hyperglycemia). After 30 min (T = 0), an intraduodenal lipid infusion (1.5 kcal/min) was commenced and continued until the end of the study. At T = 20 minutes, erythromycin (200 mg) as the lactobionate was infused intravenously over 20 min, followed by 100 mg over the next 40 min. RESULTS: Intravenous erythromycin increased the amplitude of antral waves during intraduodenal lipid infusion at both blood glucose concentrations (p < 0.01 for euglycemia and p < 0.05 for hyperglycemia). After erythromycin (T = 20 to T = 80), the frequency (p < 0.05) and amplitude (p < 0.01) of antral waves were less during hyperglycemia than euglycemia. Both propagated (p < 0.0005) and nonpropagated (p < 0.01) antral waves were decreased by hyperglycemia, but the suppression of propagated waves was greater (p < 0.05). Erythromycin reduced the frequency (p = 0.09) but increased the amplitude (p < 0.05) of phasic pyloric pressures, and decreased basal pyloric pressure (p < 0.0005). The frequency (p = 0.06) and amplitude (p < 0.05) of phasic pyloric waves during erythromycin infusion were slightly less during hyperglycemia than euglycemia, whereas there was no effect of the blood glucose concentration on basal pyloric pressure. Erythromycin increased the amplitude (p < 0.001) but not the frequency of duodenal waves; the frequency and amplitude of duodenal waves did not differ between the two blood glucose concentrations. CONCLUSIONS: Hyperglycemia attenuates the stimulation of antral pressures and propagated antral sequences by erythromycin, but not the effects of erythromycin on pyloric or duodenal motility.

Adolescent↗

PubMed2000

Ileal short-chain fatty acids inhibit gastric motility by a humoral pathway.

The aim of this study was to evaluate the nervous and humoral pathways involved in short-chain fatty acid (SCFA)-induced ileal brake in conscious pigs. The role of extrinsic ileal innervation was evaluated after SCFA infusion in innervated and denervated Babkin's ileal loops, and gastric motility was measured with strain gauges. Peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) concentrations were evaluated in both situations. The possible involvement of absorbed SCFA was tested by using intravenous infusion of acetate. Ileal SCFA infusion in the intact terminal ileum decreased the amplitude of distal and terminal antral contractions (33 +/- 1.2 vs. 49 +/- 1.2% of the maximal amplitude recorded before infusion) and increased their frequency (1.5 +/- 0.11 vs. 1.3 +/- 0.10/min). Similar effects were observed during SCFA infusion in ileal innervated and denervated loops (amplitude, 35 +/- 1.0 and 34 +/- 0. 8 vs. 47 +/- 1.3 and 43 +/- 1.2%; frequency, 1.4 +/- 0.07 and 1.6 +/- 0.06 vs. 1.1 +/- 0.14 and 1.0 +/- 0.12/min). Intravenous acetate did not modify the amplitude and frequency of antral contractions. PYY but not GLP-1 concentrations were increased during SCFA infusion in innervated and denervated loops. In conclusion, ileal SCFA inhibit distal gastric motility by a humoral pathway involving the release of an inhibiting factor, which is likely PYY.

Acetates↗

PubMed1999

Short-chain fatty acids present in the ileum inhibit fasting gastrointestinal motility in conscious pigs.

Colonic compounds, primarily short-chain fatty acids (SCFAs), inhibit gastric tone in humans. However, since colonic compounds reflux into the ileum, SCFAs might act also at the ileal level. This study evaluates the effects of the contact of SCFAs with the ileum alone towards gastrointestinal motility in fasted conscious pigs. Gastrointestinal motility was recorded during ileal infusion of a mixture containing acetate, propionate and butyrate in intact vs ileostomized animals (n = 10). Ileal infusions of isomolar (500 mmol L-1) vs isocaloric (600 kJ L-1) SCFAs were also performed. SCFA mixture reduced significantly the amplitude and increased the frequency of antral contractions in intact (motility index: 2624 +/- 503.4 vs 4077 +/- 388.2) and ileostomized pigs (motility index: 2428 +/- 678.1 vs 4709 +/- 773.4) compared with iso-osmotic saline. SCFAs at isomolar concentrations inhibited equally gastric motor pattern irrespective of their chemical structure. On the contrary, isocaloric concentrations of SCFAs induced graded effects: acetic acid being the most potent to reduce gastric motility. In conclusion, SCFAs inhibit gastrointestinal motility by a direct contact with the ileum. This inhibition was concentration dependent.

Animals↗

PubMed1999

Ileal short-chain fatty acids inhibit transpyloric flow in pigs.

BACKGROUND: Short-chain fatty acids (SCFA) found in the ileum after caecoileal reflux might trigger a physiologic ileal brake similar that induced by ileal nutrient infusion. This study evaluates gastric emptying and motility after ileal administration of SCFA. METHODS: In eight conscious pigs gastric emptying was evaluated by double dilution (liquids) and direct measurement of duodenal effluent (liquids and solids) during ileal infusions of SCFA and isotonic and hypertonic saline. Antropyloroduodenal manometry and flow were recorded concurrently. RESULTS: Ileal SCFA significantly delayed gastric emptying of liquids and solids. During SCFA infusion the emptying pattern of liquids was less pulsatile, and flow pulses had a smaller stroke volume than during isotonic saline. The antroduodenal pressure gradient was decreased, whereas pyloric tone was increased. A reduced number of antral pressure waves occurred together with an increased frequency of isolated pyloric pressure waves. CONCLUSIONS: Ileal SCFA infusion delays gastric emptying of liquid and solid as a consequence of a decreased antral and increased pyloric motility.

Animals↗

PubMed1999

Validation of a novel luminal flow velocimeter with video fluoroscopy and manometry in the human esophagus.

There is currently no ideal method for concurrently assessing intraluminal pressures and flows in humans with high temporal resolution. We have developed and assessed the performance of a novel fiber-optic laser-Doppler velocimeter, mounted in a multichannel manometric assembly. Velocimeter recordings were compared with concurrent fluoroscopy and manometry following 50 barium swallows in healthy subjects. During these swallows, the velocimeter sensor was situated in either the proximal (24 swallows) or the distal (26 swallows) esophagus. It signaled intraluminal flow following 46 of 50 swallows. A greater mean number of deflections were recorded in the distal compared with the proximal esophagus (4. 3 vs. 2.4, P = 0.001). The maximal flow velocity recorded did not differ between the proximal and distal esophagus (76.7 vs. 73.8 mm/s). No velocimeter signals commenced after fluoroscopic lumen occlusion. The velocimeter signals were closely temporally related to fluoroscopic barium flow. Upward catheter movement on swallowing sometimes appeared to cause a velocimeter signal. Manometrically "normal" swallows were no different from "abnormal" swallows in the number and velocity of deflections recorded by the velocimeter. This novel instrument measures intraluminal flow velocity and pressures concurrently, thus enabling direct study of pressure-flow relationships. Flow patterns differed between the proximal and distal esophagus.

Adult↗

PubMed1998

Mechanisms of gastro-oesophageal reflux in the ferret.

Transient lower oesophageal sphincter (LOS) relaxation is the major mechanism of gastro-oesophageal reflux in humans--an event unassociated with swallowing. Mechanisms involved in triggering transient LOS relaxation are poorly understood, and their further study requires a small animal model. In this study we aimed to establish methods for prolonged ambulant oesophageal manometry in ferrets, and to determine motor events associated with reflux episodes and their triggering by different gastric nutrient loads. Forty-two studies were performed on nine ferrets with chronic cervical oesophagostomies, through which a manometric assembly was introduced and secured to a collar, which incorporated a microphone for detection of swallows. The assembly included a gastric feeding channel, one gastric and four oesophageal manometric sideholes, a 2.5-cm-long LOS sleeve sensor, and an oesophageal pH electrode. Intragastric infusions were given over 2 min, the first after a 30-min control recording period, and in 29/42 studies, a second infusion was given 60 min later. Infusions were either 25 mL 10% dextrose solution, pH 3.5 (22 studies), 25 mL triglyceride emulsion (Intralipid) pH 3.5 (11 studies), or 25 mL air (nine studies). Episodes of oesophageal acidification were absent before gastric infusions. After infusion, 2.1 +/- 0.2 episodes occurred over the first 30 min. After glucose infusion, 15/18 acidification episodes (83%) occurred during transient LOS relaxation, and 3/18 (17%) occurred after gradual (< 1 mmHg sec-1) downward drifts in basal LOSP to < 2 mmHg. After lipid infusion two acidification episodes occurred, both during transient LOS relaxation. Mean duration of transient LOS relaxation was 8.0 +/- 0.4 sec. All infusions increased occurrence of transient LOS relaxation to a similar extent, each of which ended with primary peristalsis. We conclude that gastric infusion of glucose, lipid and gas are all effective in provoking gastro-oesophageal reflux in ferrets. Reflux occurs through similar mechanisms to those seen in humans, i.e. increased triggering of transient LOS relaxation. The conscious ferret is therefore an appropriate model for future studies of manipulation of mechanisms giving rise to gastro-oesophageal reflux.

Animals↗

PubMed1998

Changes in pyloric resistance induced by erythromycin.

Erythromycin increases gastric emptying but the characteristics of transpyloric flow and the contribution of pyloric resistance to the mechanisms of increased flow are unknown. Transpyloric outflow and gastroduodenal pressures were studied in eight anaesthetized pigs during intravenous infusion of erythromycin (10 mg kg-1). Erythromycin increased emptying of saline through an increased stroke volume of individual flow pulses (13.7 +/- 1.24 vs. 3.6 +/- 1.30 mL) rather than by decreasing the interval between flow pulses (3.9 +/- 0.55 vs. 3.2 +/- 0.30 pulse.min-1). This flow pattern was associated with more frequent antral contractions of larger amplitude originating from the upper part of the gastric antrum, suppression of isolated pyloric pressure waves and significant reduction of the pyloric resistance to flow (2.3 +/- 0.21 vs. 4.6 +/- 0.46 mmHg mL-1 s-1). The decreased resistance originated from a different temporal relationship between antropyloric pressure event and flow pulses that occurred almost simultaneously during erythromycin.

Animals↗

PubMed1998

Relationships between cecoileal reflux and ileal motor patterns in conscious pigs.

Ileal infusion of cecocolonic contents, used to mimick reflux, enhanced terminal ileal motility, increasing the frequencies of prolonged propagated contractions (PPC) and discrete clustered contractions (DCC). Because the reflux rate in dogs and humans is marginal, the relationship of these motor patterns to reflux remained putative. In six conscious pigs, the ileal pH, used to indicate reflux event, was measured 10 and 5 cm proximal to the ileocecal sphincter (ICS). Ileal motility was evaluated with three strain gauges 15, 10, and 5 cm proximal to the ICS. Ileal pH dips were observed about eight times per hour in the fasting or fed state, and 46% of the pH dips were preceded by a retrograde contraction. During pH dips, frequency of ileal contractions not classified as PPC or DCC was significantly increased. Of the PPC 52% occurred immediately after the start of the dip and might act as a clearance mechanism because dips associated with PPC were of smaller amplitude and duration than those not associated with PPC. Most DCC also occurred during pH dips but their delay to the onset of the dip was longer. The pig presents frequent cecoileal reflux events associated with ileal motor patterns, some of them might facilitate reflux, whereas others act as a clearance mechanism.

Animals↗

PubMed1998

Erythromycin gastrokinetic activity is partially vagally mediated.

Erythromycin overcomes postvagotomy gastroparesia in patients without a distal stomach and functional pylorus. We investigate the role of the vagus in gastric emptying increased by erythromycin, using a model that preserves the physiology of the distal stomach and pylorus. The effects of erythromycin lactobionate (10 mg/kg) on transpyloric flow pattern and pyloric resistance were evaluated during repetitive bilateral vagal cooling in anesthetized pigs. Vagal cooling during erythromycin infusion produced a marked decreased of pyloric outflow (23 +/- 1.1 vs 50 +/- 2.6 ml/min) related to a reduced stroke volume of the flow pulses (7.8 +/- 3.31 vs. 14.1 +/- 2.44 ml). The amplitude and frequency of gastric and duodenal pressure events were unchanged or slightly reduced during vagal cooling. The smaller stroke volume of flow pulse was the consequence of increased pyloric resistance (6.2 +/- 1.98 vs. 2.3 +/- 0.21 mmHg.ml-1.s), which is associated with changes in the temporal relationship between a pyloric pressure event and flow pulse. In conclusion, erythromycin activity on the pylorus requires the integrity of vagal pathways. Enhancement of gastric outflow by erythromycin is also modulated by the vagus, since pyloric resistance was able to overcome increased gastric motility.

Animals↗