Pharmacological modulation of the spatiotemporal disposition of micromotions in the intact resting urinary bladder of the rabbit; their pattern is under both myogenic and autonomic control.

OBJECTIVES: To explore and characterize the disposition and dynamics of micromotions in the wall of the intact resting teradotoxinized urinary bladder of the rabbit before and after the administration of adrenergic and cholinergic pharmaceutical agents. METHODS: Spatiotemporal maps and related intravesical pressure were used to analyse propagating patches of contractions (PPCs) and their component individual myogenic contractions [propagating individual contractions (PICs)] in the wall of the tetradotoxinized urinary bladder. RESULTS: The bladder wall exhibited two contractile states that were of similar frequencies to those of the two types of electrophysiological discharge described in previous studies; the first, in which cyclic PPCs predominated, the second in which small irregular PICs predominated. The addition of carbachol increased the size, frequency, speed and distance of propagation of PPCs, whereas the addition of isoprenaline temporarily halted the incorporation of PICs into PPCs, and reduced patch size and total area undergoing contraction. The RhoA kinase (ROCK) inhibitor Y-27632 reduced both largest patch index and mean patch size. Both carbenoxolone and ROCK inhibition decreased the duration of PPCs. Carbenoxolone also prolonged duration and accelerated PPC propagation velocity. The authors postulate that these differences arise from differing effects of these agents on myocytes and interstitial cells within the stress environment of the bladder, influencing the development, coordination and propagation of PPCs. CONCLUSIONS: The timings and structure of spontaneous micromotions in the wall of the isolated bladder change when it is treated with sympathetic/parasympathetic agonists and with myogenically active agents. Correspondingly, disorders of bladder wall contraction may result from disorders of either neurogenic or myogenic signalling and may be amenable to treatment with combinations of agents that influence both.

Characterisation of the contractile dynamics of the resting ex vivo urinary bladder of the pig.

OBJECTIVES: To characterise the area and movements of ongoing spontaneous localised contractions in the resting porcine urinary bladder and relate these to ambient intravesical pressure (Pves ), to further our understanding of their genesis and role in accommodating incoming urine. MATERIALS AND METHODS: We used image analysis to quantify the areas and movements of discrete propagating patches of contraction (PPCs) on the anterior, anterolateral and posterior surfaces of the urinary bladders of six pigs maintained ex vivo with small incremental increases in volume. We then correlated the magnitude of Pves and cyclic changes in Pves with parameters derived from spatiotemporal maps. RESULTS: Contractile movements in the resting bladder consisted only of PPCs that covered around a fifth of the surface of the bladder, commenced at various sites, and were of ≈6 s in duration. They propagated at around 6 mm/s, mainly across the anterior and lateral surface of the bladder by various, sometimes circular, routes in a quasi-stable rhythm, and did not traverse the trigone. The frequencies of these rhythms were low (3.15 cycles/min) and broadly similar to those of cyclic changes in Pves (3.55 cycles/min). Each PPC was associated with a region of stretching (positive strain rate) and these events occurred in a background of more constant strain. The amplitudes of cycles in Pves and the areas undergoing PPCs increased after a sudden increase in Pves but the frequency of cycles of Pves and of origin of PPCs did not change. Peaks in Pves cycles occurred when PPCs were traversing the upper half of the bladder, which was more compliant. The velocity of propagation of PPCs was similar to that of transverse propagation of action potentials in bladder myocytes and significantly greater than that reported in interstitial cells. The size of PPCs, their frequency and their rate of propagation were not affected by intra-arterial dosage with tetrodotoxin or lidocaine. CONCLUSIONS: The origin and duration of PPCs influence both Pves and cyclic variation in Pves . Hence, propagating rather than stationary areas of contraction may contribute to overall tone and to variation in Pves . Spatiotemporal mapping of PPCs may contribute to our understanding of the generation of tone and the basis of clinical entities such as overactive bladder, painful bladder syndrome and detrusor overactivity.

New Zealand green-lipped mussels (Perna canaliculus) enhance non-haem iron absorption in vitro.

Fe bioavailability can be manipulated by the nutritional composition of a meal. Ascorbic acid and unidentified components of meat, fish and poultry, but particularly beef, all appear to enhance the absorption of non-haem Fe. The aim of the present study is to identify whether extracts of green-lipped mussels (GLM; Perna canaliculus) enhance non-haem Fe absorption in Caco-2 cells and to compare the effect with that of beef. Raw GLM and raw beef homogenates were digested in vitro with pepsin at pH 2, and pancreatin and bile salts at pH 7. Tracer 55Fe was used to measure cellular Fe uptake. Ascorbic acid was used as a positive control and egg albumin, exposed to the same in vitro digestion process, was used as a negative control. Caco-2 cell monolayers were incubated with treatments for 60 min. All values were standardised per µg of GLM, egg albumin, beef or ascorbic acid. The results showed that ascorbic acid enhanced non-haem Fe absorption to the highest degree. Beef and GLM digestates both significantly enhanced Fe absorption compared with egg albumin. In conclusion, GLM digestate significantly enhances non-haem Fe uptake in Caco-2 cells with a similar magnitude to that of beef.

Post-weaning effects of milk and milk components on the intestinal mucosa in inflammation.

Many milk-derived components have immunomodulatory and anti-inflammatory properties, and some of these reduce intestinal inflammation when orally administered to animal models of colitis. However, the potential for ruminant milk or milk components to benefit people with intestinal inflammatory disorders (such as Inflammatory Bowel Disease) has not been well-researched. This review describes published research into mechanisms by which ruminant milk and its components may have beneficial effects when consumed by people who have intestinal inflammation.

Spatiotemporal Mapping Techniques Show Clozapine Impairs Neurogenic and Myogenic Patterns of Activity in the Colon of the Rabbit in a Dose-Dependent Manner.

Background: Clozapine, an antipsychotic used in treatment-resistant schizophrenia, has adverse gastrointestinal effects with significant associated morbidity and mortality. However, its effects on defined patterns of colonic contractile activity have not been assessed. Method: We used novel radial and longitudinal spatiotemporal mapping techniques, combined with and monitoring of ambient lumen pressure, in ex vivo preparations of triply and of singly haustrated portions of rabbit colon. We identified the contractile patterns of mass peristalses, fast phasic, and ripple contractions and directly qualified the effects of clozapine, at concentrations of 10 µmol/L, 20 µmol/L, and 30 µmol/L, and of norclozapine, the main metabolite of clozapine, on contractile patterns. The effects of carbachol, serotonin and naloxone on clozapine-exposed preparations were also determined. Tetradotoxin was used to distinguish neurogenic from myogenic contractions. Results: At 10 µmol/L, clozapine temporarily abolished the longitudinal contractile components of mass peristalsis, which on return were significantly reduced in number and amplitude, as was maximal mass peristaltic pressure. These effects were reversed by carbachol (1 µmol/L) and to some extent by serotonin (15 µmol/L). At 10 µmol/L, myogenic ripple contractions were not affected. At 20 µmol/L, clozapine had a similar but more marked effect on mass peristalses with both longitudinal and radial components and corresponding maximal pressure greatly reduced. At 30 µmol/L, clozapine suppressed the radial and longitudinal components of mass peristalses for over 30 min, as well as ripple contractions. Similar dose-related effects were observed on addition of clozapine to the mid colon. At 20 µmol/L, norclozapine had opposite effects to those of clozapine, causing an increase in the frequency of mass peristalsis with slight increases in basal tone. These slightly augmented contractions were abolished on addition of clozapine. Concentrations of norclozapine below 20 µmol/L had no discernible effects. Conclusion: Clozapine, but not norclozapine, has potent effects on the motility of the rabbit colon, inhibiting neurogenic contractions at lower concentrations and myogenic contractions at higher concentrations. This is the likely mechanism for the serious and life-threatening gastrointestinal complications seen in human clozapine-users. These effects appear to be mediated by cholinergic and serotonergic mechanisms. Spatiotemporal mapping is useful in directly assessing the effects of pharmaceuticals on particular patterns of gastrointestinal motility.

The jejunum is the main site of absorption for anthocyanins in mice.

Intestinal absorption of anthocyanins (ACNs) was studied in vitro by comparing ACN disappearance from the mucosal solution of Ussing chambers not containing any tissue (controls) and that of Ussing chambers containing segments of mouse duodenum, jejunum, ileum or colon. The tissues were mounted in the chambers and bathed with Ringer's solution (RS) adjusted to a pH representative of the respective segments in vivo. The chambers were kept at 37 degrees C and RS was perfused continuously with carbogen (95% O(2)/5% CO(2)). After the addition of an ACN extract to the mucosal solution, samples from both the mucosal side and the serosal side were withdrawn at 10, 40, 80 and 120 min and analyzed for ACN concentration using reversed-phase HPLC with photodiode array detection. The highest absorption of ACNs occurred in chambers mounted with jejunal tissue (max absorption rate, 55.3+/-7.6%). Minor absorption occurred with duodenal tissue (10.4+/-7.6%), with no absorption recorded when tissues from the ileum or colon were used. This study demonstrates for the first time that ACN absorption in mice occurs predominantly in the jejunum.

The flavonol quercetin-3-glucoside inhibits cyanidin-3-glucoside absorption in vitro.

At present, little is known about the mechanisms responsible for intestinal absorption of anthocyanins (ACNs). For example, it has not yet been established if ACNs are absorbed through an active transport mechanism, such as the sodium-dependent glucose transporter (SGLT1), or by passive diffusion. Previously, we found that the absorption of ACNs differs between regions of the digestive tract and is maximal in the jejunum, suggesting that an active transport mechanism is involved. In the present study, we examined the effect of d-glucose (main substrate of SGLT1), phloridzin (inhibitor of SGLT1), and quercetin-3-glucose (Q3G, a flavonol) on the absorption of cyanidin-3-glucoside (C3G; approximately 5 micromol/L) by mouse jejunum mounted in Ussing chambers. We found that the presence of either D-glucose (10, 20, and 40 mmol/L) or phloridzin (50, 100, and 200 micromol/L) resulted in a small but insignificant inhibition of C3G disappearance from the mucosal solution (decrease of disappearance with glucose, 33%; with phloridzin, 18%; NS). However, when the flavonol Q3G (50 micromol/L) was added to the mucosal solution together with the C3G, the disappearance of C3G was significantly decreased (74%; p < 0.001), and Q3G disappeared instead. In addition, we found phloretin and quercetin, the aglycones of phloridzin and Q3G, respectively, present in the mucosal solution and tissue extracts, indicating hydrolysis of these compounds by the enterocytes of the jejunum. In contrast, the aglycone cyanidin was not detected at all. Our results show that in the mouse small intestine, ACN absorption is not solely dependent on the activity of the SGLT1 transporter, as d-glucose and phloridzin had only a slight effect on uptake. Q3G, however, clearly inhibited C3G disappearance. These results suggest that there might be a competitive inhibition between C3G and Q3G absorption. It is possible that an absorption mechanism other than the SGLT1 is involved, which has a structural preference toward flavonols.

Anthocyanin absorption and antioxidant status in pigs.

The effect of a simultaneous intake of food or flavonoids on anthocyanins absorption and antioxidant status in pigs was investigated. Twelve male pigs at 27.1 +/- 0.7 kg BW fitted with jugular venous cannulae were maintained in individual metabolic crates. The animals were each given one of three dietary treatments in random order: blackcurrant powder (BC) to give a dose of 100 mg total ACNs/kg BW mixed either with water and sugar (Diet A), cereal (Weet-Bix), milk, and sugar (Diet B), or cereal, milk, sugar, and an additional flavonol (rutin, approximately 100 mg/kg BW) (Diet C). The four major anthocyanins of BC, delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, and cyanidin-3-rutinoside, were identified and quantified by HPLC-PDA in all three diets. In the pig plasma, four peaks with a reversed pattern to those of anthocyanins in the BC extract were detected. The total amount of anthocyanins absorbed was not significantly different between the three diets, but the rate of absorption and subsequent decline was slower following administration of diet B and C than diet A. All three diets increased antioxidant capacity when measured by the FRAP assay but not when measured by the ORAC and non-protein ORAC assay. However, the increase was delayed and did not appear until 4 h after ingestion, at a time when plasma anthocyanin levels had returned to baseline. The present study demonstrates that the simultaneous intake of food or other flavonoids delays the absorption profile for anthocyanins. Our results also suggest that the increase in antioxidant capacity is not due to dietary anthocyanins but may be due to metabolites that result from anthocyanin consumption.

Ex vivo motility in the base of the rabbit caecum and its associated structures: an electrophysiological and spatiotemporal analysis.

We examined the coordination between contractile events at different sites in the basal portion of the rabbit caecum and its associated structures that were identified by electrophysiological recordings with simultaneous one-dimensional, and a novel two-dimensional, spatiotemporal mapping technique. The findings of this work provide evidence that the caecum and proximal colon/ampulla coli act reflexly to augment colonic outflow when the caecum is distended and mass peristalsis instituted, the action of the latter overriding the inherent rhythm and direction of haustral propagation in the adjacent portion of the proximal colon but not in the terminal ileum. Further, the findings suggest that the action of the sacculus rotundus may result from its distension with chyme by ileal peristalsis and that the subsequent propagation of contraction along the basal wall of the caecum towards the colon may be augmented by this local distension.

Cardiovascular, respiratory, and body temperature responses of sheep to the ergopeptides ergotamine and ergovaline.

OBJECTIVE: To compare the effects of the ergot alkaloid ergovaline with effects of ergotamine on blood pressure, heart rate, respiratory rate, and body temperature in conscious sheep. ANIMALS: 3 sheep with indwelling arterial catheters. PROCEDURE: Ergotamine and ergovaline were injected IV (20 nmol/kg), and their effects on arterial blood pressure, heart rate, respiratory rate and pattern, body temperature, and skeletal muscle electromyographic activity were compared with control values obtained following injections of saline (0.9% NaCI) solution or acetone. RESULTS: Both ergopeptides caused immediate and significant increases in blood pressure (50 to 75 mm Hg) without concomitant increases in heart rate. Ergovaline but not ergotamine significantly increased pulse pressure (35 mm Hg). Both ergopeptides resulted in decreased respiratory rate and increased respiratory depth within the first hour of administration. Body temperature was decreased slightly upon ergopeptide administration but continued to increase thereafter, with greater increases developing with ergovaline than with ergotamine. Increased body temperatures of 3.0 to 3.5 C were maintained for at least 10 hours. Respiratory rate was increased to rates as high as 210 to 220 breaths/min in association with hyperthermia. Ergopeptides had no effect on skeletal muscle electromyographic activity. CONCLUSIONS AND CLINICAL RELEVANCE: In sheep, ergovaline has similar effects to ergotamine on cardiovascular and pulmonary function and body temperature but is more potent. These effects are consistent with clinical signs observed in the toxicoses developed when ruminants ingest grass with high concentrations of ergopeptides.

Gene expression changes in the colon epithelium are similar to those of intact colon during late inflammation in interleukin-10 gene deficient mice.

In addition to their role in absorption and secretion, epithelial cells play an important role in the protection of the colon mucosa from the resident microbiota and are important for the maintenance of homeostasis. Microarray analysis of intact colon samples is widely used to gain an overview of the cellular pathways and processes that are active in the colon during inflammation. Laser microdissection of colon epithelial cells allows a more targeted analysis of molecular pathways in the mucosa, preceding and during inflammation, with potentially increased sensitivity to changes in specific cell populations. The aim of this study was to investigate the molecular changes that occur in early and late inflammation stages in colon epithelium of a mouse model of inflammatory bowel diseases. Microarray analysis of intact colon samples and microdissected colon epithelial cell samples from interleukin-10 gene deficient and control mice at 6 and 12 weeks of age was undertaken. Results of gene set enrichment analysis showed that more immune-related pathways were identified between interleukin-10 gene deficient and control mice at 6 weeks of age in epithelial cells than intact colon. This suggests that targeting epithelial cells could increase sensitivity for detecting immune changes that occur early in the inflammatory process. However, in the later stages of inflammation, microarray analyses of intact colon and epithelium both provide a similar overview of gene expression changes in the colon mucosa at the pathway level.

Lycopene bioaccessibility and starch digestibility for extruded snacks enriched with tomato derivatives.

To improve the nutritional value of energy-dense extruded snacks, corn grits were replaced with tomato paste and/or tomato skin powder at ratios of 5, 10, and 20% and extruded to make expanded snack foodlike products. Using a model digestion system, lycopene bioaccessibility and uptake from the snacks into Caco-2 cells were determined. The digestibility of the starch, the main nutrient component of the snacks, was also investigated. While extrusion cooking reduced the lycopene content of the snacks, the proportion of bioaccessible lycopene increased. Lycopene uptake by the Caco-2 cells from the extruded snacks exceeded that of the control in which the lycopene was not extruded, by 5% (p < 0.05). The digestibility of starch in the snacks varied depending on the type of tomato derivative and its concentration. Optimization of the extrusion cooking process and the ingredients can yield functional extruded snack products that contain bioavailable lycopene.

An acute ileal amino acid digestibility assay is a valid procedure for use in human ileostomates.

An acute (24-h) feeding/digesta sampling procedure was evaluated in a preliminary study using growing pigs. The validated acute procedure was then applied using human ileostomates to determine apparent and true ileal amino acid digestibilities of 4 dietary protein sources. The acute method involved feeding ileostomized pigs a single meal containing the test protein as part of a purified diet, with no previous dietary adaptation, followed by an 8-h collection of digesta. Apparent ileal N digestibility did not differ between the acute and conventional (14-d study) procedures. Eight adult human ileostomates each received a single meal of protein-free biscuits and a drink containing sodium caseinate, whey protein concentrate, soy protein isolate, or soy protein concentrate; this meal was followed by a 9-h total digesta collection period. Acid insoluble ash was used as an indigestible marker. True ileal amino acid digestibilities (means +/- SE) ranged from 90.5 +/- 2.74% for cysteine in soy protein concentrate to 105.3 +/- 5.66% for cysteine in sodium caseinate and were markedly higher than their apparent counterparts. True ileal digestibilities for total nitrogen were 101.9 +/- 0.70, 98.3 +/- 0.80, 99.5 +/- 0.80, and 98.5 +/- 1.20% for sodium caseinate, whey protein concentrate, soy protein isolate, and soy protein concentrate, respectively. The 4 protein sources were virtually completely digested in humans by the end of the small intestine.