Biomedical subjects

M A Plaza

Publications and source records attributed to M A Plaza.

At least 19 recordsLinked to original sources

PubMed2006

The role of tyrosine kinase in prostaglandin E2 and vanadate-evoked contractions in rabbit duodenum in vitro.

Prostaglandin E2 (PGE2) can interact with at least four cell surface receptors (EP1-EP4) in smooth muscle, which evokes a variety of intracellular responses depending on the G protein to which the cell surface receptors are coupled. The activation of G protein-coupled receptors and receptor tyrosine kinases can lead to the phosphorylation of tyrosine residues of various cellular proteins. The aim of this study was to examine the role of tyrosine phosphorylation in PGE2, vanadate and carbachol-evoked contractions. PGE2, vanadate, and carbachol induced contractile motor responses in the longitudinal smooth muscle of rabbit duodenum. PGE2-evoked contractions decreased in the presence of genistein or tyrphostin B44. PGE2-evoked contractions increased in the presence of vanadate. Vanadate-evoked contractions decreased in the presence of genistein. In contrast, tyrphostin 47 increased the vanadate-evoked contractions. Vanadate-evoked contractions were reduced in the presence of Ca2+-free solutions, verapamil, or indomethacin. U-73122 decreased PGE2-evoked contractions. Carbachol-evoked contractions decreased in the presence of genistein, tyrphostin B44 or tyrphostin 47. Our results suggest that PGE2, vanadate or carbachol-evoked contractions are mediated by protein tyrosine phosphorylation. Protein tyrosine phosphorylation might cause an increase in calcium influx through voltage-dependent channels and the release of prostaglandins in the longitudinal smooth muscle of the rabbit duodenum.

Animals↗

PubMed2005

The role of NO in the contractility of rabbit small intestine in vitro: effect of K+ channels.

Nitric oxide (NO) is an inhibitory neurotransmitter of intestinal smooth muscle cells. The aim of this study was to determine the role of NO in the contractility of rabbit small intestine smooth muscle in vitro. The amplitude, frequency and tone of spontaneous contractions in longitudinal and circular smooth muscle of duodenum, jejunum and ileum were determined and the sodium nitroprusside (SNP), acetylcholine (ACh) and KCl responses were quantified. L-NAME, L-NNA, L-arginine and D-arginine did not affect the amplitude, frequency and tone of spontaneous contractions. ODQ (10(-6) M) increased the tone of spontaneous contractions of the types of tissues examined, and the amplitude in ileum, without modifying the frequency. SNP (10(-4) M) evoked relaxations that were not influenced by atropine (10(-6) M) plus guanethidine (10(-6) M), apamin (10(-8) M) or glybenclamide (10(-6) M), but were increased by TTX (10(-6) M) and verapamil (10(-7) M). SNP-induced relaxations were reduced by charybdotoxin (10(-8) M) and ODQ (10(-6) M). ODQ (10(-5) M) reduced ACh-induced contractions, but it did not influence KCl-evoked contractions. Those results suggest that NO modulates the spontaneous contractions of small intestine in rabbits. This effect is mediated by cGMP and Ca2+-dependent K+ channels of large conductance.

Acetylcholine↗

PubMed2004

The role of Ca2+ in the contractility of rabbit small intestine in vitro.

This study evaluated the role of Ca2+ in spontaneous and ACh- and KCl-induced contractions in longitudinal and circular smooth muscle from rabbit small intestine in vitro. In the first experiment, the amplitude, frequency and tone of spontaneous contractions in longitudinal and circular smooth muscle of small intestine were determined and, in the second experiment, the ACh- and KCl-induced responses of longitudinal and circular smooth muscle were measured. Atropine and guanethidine reduced the amplitude and tone of contractions in longitudinal and circular muscle, but reduced the frequency of contractions in circular muscle, only. TTX attenuated the amplitude of contractions and decreased the tone of contractions in longitudinal muscle, but increased the tone in circular muscle. Ca2+-free solutions, verapamil, nifedipine and caffeine diminished the three parameters of spontaneous contractions. Thapsigargin and cyclopiazonic acid increased the amplitude and tone of contractions in ileum longitudinal muscle, only, and cyclopiazonic acid increased the amplitude of contractions in circular muscle. Ca2+-free solutions, verapamil, nifedipine, thapsigargin, cyclopiazonic acid, and caffeine diminished ACh- and KCl-induced contractions. Those results suggest that extracellular Ca2+ plays a role in spontaneous contractions, and extracellular and intracellular Ca2+ participate in the ACh- and KCl-induced contractions of rabbit small intestine.

Acetylcholine↗

PubMed2003

Role of prostaglandins in lipopolysaccharide effects on K+-induced contractions in rabbit small intestine.

AIM: The mediators of the pathophysiologcal symptoms of septic shock are not completely understood. The aim of this work was to investigate the effect of lipopolysaccharide (LPS) on the K+-induced response of longitudinal segments of rabbit small intestine in vitro and the possible role of prostaglandins. METHODS AND RESULTS: Rabbits were treated with intravenously injected LPS. After 90 min animals were killed and intestinal segments were mounted in an organ bath. Lipopolysaccharide (0.2 microg kg-1) inhibited K+-induced contractions (60 mm) by 68% in duodenum, 58% in jejunum and 52% in ileum. Indomethacin antagonized LPS actions when injected 15 min before LPS. PGE2 reduced K+-induced contractions, imitating LPS effects. In contrast, contractions induced by K+ increased when intestinal segments were incubated in vitro with LPS for 90 min. The LPS (0.3 microg mL-1) increased K+-induced contractions (60 mm) by 46% in duodenum, 63% in jejunum and 85% in ileum. The LPS effect was antagonized by indomethacin at 10-6 m in duodenum and jejunum and at 10-8 m in ileum. PGE2 evoked dose-dependent contractions when added to the bath in duodenum, jejunum and ileum. CONCLUSION: These results suggest that effect of LPS on K+-induced contractions in the rabbit small bowel may be mediated by prostaglandin E2.

Animals↗

PubMed2003

Central tumour necrosis factor-alpha mediates the early gastrointestinal motor disturbances induced by lipopolysaccharide in sheep.

Cytokines are involved in fever and other symptoms of the acute phase response induced by endotoxins. The aim of this work was to study the involvement of central tumour necrosis factor-alpha (TNF-alpha) in the changes induced by lipopolysaccharide (LPS) on gastrointestinal (GI) motility in sheep. Body temperature and myoelectric activity of the antrum, duodenum and jejunum was recorded continuously. Intravenous (i.v.) administration of LPS (0.1 micro g kg-1)-induced hyperthermia, decreased gastrointestinal myoelectric activity and increased the frequency of the migrating motor complex (MMC). These effects started 40-50 min after LPS and lasted for 6-7 h. TNF-alpha (50 and 100 ng kg-1) mimicked these effects when injected intracerebroventricularly (i.c.v.) but not i.v. Pretreatment with soluble recombinant TNF receptor (TNFR:Fc, 10 micro g kg-1, i.c.v.) abolished the TNF-induced actions and reduced those evoked by LPS. Furthermore, the effects induced by either LPS or TNF were suppressed by prior i.c.v. injection of indomethacin (100 micro g kg-1). In contrast, the i.v. injections of TNFR:Fc or indomethacin were ineffective. Our data suggest that LPS disturbs GI motility in sheep through a central pathway that involves TNF-alpha and prostaglandins sequentially.

Animals↗

PubMed2002

Effect of lipopolysaccharide on rabbit small intestine muscle contractility in vitro: role of prostaglandins.

The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) on spontaneous contractions and acetylcholine (ACh) induced contractions of rabbit intestinal segments in vitro, with two different protocols: intestinal segments isolated from LPS-treated rabbits and intestinal segments incubated with LPS. The frequency of spontaneous movements decreased significantly in LPS-treated rabbits at 2 microg kg-1 in the duodenum and 20 microg kg-1 in the duodenum, jejunum and ileum. LPS (0.2 microg kg-1) reduced significantly the ACh contractions (10-6 mol L-1) in the duodenum (61%), jejunum (48%) and ileum (21%). Indomethacin (1, 5 and 10 mg kg-1) administered 15 min before LPS (0.2 microg kg-1) antagonized the LPS effects on the ACh-induced contractions. Prostaglandin (PG)E2 (8 microg kg-1) inhibited significantly the frequency of spontaneous contractions in the ileum and reduced the ACh-induced contractions in the three segments, mimicking the LPS effects. The amplitude and frequency of contractions in rabbit intestinal segments previously incubated with LPS (0.03, 0.3, 3 and 30 microg mL-1) were not modified with respect to the control. The ACh-induced contractions (10-4 mol L-1) were significantly reduced after 90 min of incubation with LPS. The inhibition of LPS (0.3 microg mL-1) was 43% in the duodenum, 35% in the jejunum and 17% in the ileum. Indomethacin added before LPS blocked the effect of LPS on the ACh-induced contractions in the duodenum, jejunum and ileum. These results show that LPS decreases intestinal contractility in rabbits and suggest that PGs are implicated in these actions.

Acetylcholine↗

PubMed2001

5-hydroxytryptamine and the gastrointestinal migrating motor complex.

The migrating motor complex (MMC) is the basic cyclic pattern of gastrointestinal motility that is observed in the interdigestive periods in humans as well as in monogastric animals. Among the mediators involved in its regulation, an increasing number of reports point out that 5-hydroxytryptamine (5-HT) has a pivotal role. Taking into account that this pattern is disturbed in patients suffering from several gastrointestinal disorders, studies leading to a better understanding of 5-HT actions have special relevance. This article reviews the current knowledge on the role of 5-HT receptors in the control of the MMC.

Animals↗

PubMed1999

Effects of recombinant human erythropoietin on functional and injury endothelial markers in peritoneal dialysis patients.

Clinical effects of recombinant human erythropoietin (rHuEPO) such as thrombosis, convulsions, hyperviscosity, hypertension, and angiogenic effect in culture cells have been described. We studied the rHuEPO effect on endothelial damage markers and endothelial function markers: tissue-type plasminogen activator (t-PA), nitrate (NO3), thrombomodulin (TM), and von Willebrand factor (vWF). Twenty-six peritoneal dialysis patients treated with rHuEPO and 19 controls were included. The study design for rHuEPO patients consisted of four periods: long-term treatment (rHuEPO-1); 2 months of withdrawal (rHuEPO-2); and 4 months on 5000 IU/week rHuEPO subcutaneously, with markers being measured after 2 months (rHuEPO-3) and after 4 months (rHuEPO-4). After 2 months of rHuEPO withdrawal, a decrease in hemoglobin level appeared (11+/-1.8 g/dL to 9.2+/-1.5 g/dL, p < 0.01). After rHuEPO reintroduction, this value reached 10.6+/-1.5 g/dL at two months, and 11.1+/-1.4 g/dL at four months. A significant increase in t-PA ratio was observed from two months without rHuEPO to two months on rHuEPO, returning to previous values after four months. Similarly, TM increased for patients with creatinine clearances (CrC) < 5 mL/min. No changes in the higher-than-normal plasma vWF levels were found during the various periods. A statistically significant lower value was found in controls compared with rHuEPO-4 patients. A statistically significant increase in NO3 levels was observed in the pre-venous occlusion (VO) test immediately after the re-introduction of rHuEPO. This increment returned to prior values four months after rHuEPO was reintroduced. Our results show that rHuEPO treatment causes an increase in some endothelial damage markers (TM, t-PA) and modifies endothelial function markers (t-PA ratio, NO3). These changes might favor thrombosis and atherosclerosis.

Adult↗

PubMed1997

Altered concentrations of appetite regulators may contribute to the development and maintenance of HIV-associated wasting.

OBJECTIVE: To examine the relation of circulating appetite neuropeptides, CCK-8 sulphate (CCK-8s) and beta-endorphin, and the tumour necrosis factor-alpha (TNF-alpha) and soluble TNF receptors (sTNFR) to the anorexia and wasting associated with HIV-infection. DESIGN: Cross-sectional analysis. SETTING: A university-based HIV/AIDS ambulatory clinic in Madrid, Spain. PARTICIPANTS: Thirty-six randomly selected AIDS patients without concomitant diseases or secondary infections were classified into two groups: 19 patients with wasting and 17 with normal body weight, and 18 healthy controls. MEASUREMENTS: Nutritional status was evaluated by anthropometry, laboratory parameters and self-report of appetite. Plasma levels of TNF-alpha and sTNFR proteins p55 (sTNFR-p55) and p75 (sTNFR-p75) were determined by enzyme immunoassay, whereas CCK-8s and beta-endorphin levels were measured by radioimmunoassay. RESULTS: AIDS patients with wasting had significantly higher plasma concentrations of CCK-8s, but lower levels of beta-endorphin when compared to well-nourished AIDS patients (P < 0.01) or controls (P < 0.001). Mean levels of TNF-alpha, and sTNFR-p55 and sTNFR-p75 were greater in AIDS patients with wasting than in asymptomatic AIDS patients or in controls. No significant association was observed between any of these circulating peptides and the parameters of malnutrition. CONCLUSIONS: An activation of the TNF system, together with reciprocal changes in plasma concentrations of two neuropeptides with opposing appetite regulation, that is increased concentrations of CCK-8s but lower levels of beta-endorphin, are associated with the presence of HIV wasting. We hypothesize that these changes may contribute to the development of HIV wasting by producing a pathological inhibition of appetite.

Acquired Immunodeficiency Syndrome↗

PubMed1997

The effect of Mn2+, Zn2+, Ba2+ and Ca2+ on spontaneous motility in sheep duodenum in vitro.

1. The effects of several ions, Mn2+, Zn2+, Ba2+ and Ca2+, on spontaneous motility were investigated in longitudinal smooth muscle strips from sheep duodenum, in vitro. 2. Mn2+ (0.5-1.5 mM) and Zn2+ (0.5-5 mM) inhibited both the amplitude and frequency of motility in Krebs solution and in Ca(2+)-free medium. 3. Ba2+ (0.5-5 mM) evoked three types of contractile responses: (i) an increase in the frequency and a reduction of the amplitude of spontaneous contractions; (ii) a slight increase in muscle tone of the phasic contractions; and (iii) a rapid initial phasic contraction followed by slowly fading contraction. Ca2+ induced two kinds of responses in spontaneous motility: (i) a fast phasic contraction, followed by an increase in the amplitude and frequency of phasic contractions with no changes in its tone; and (ii) an increase in the amplitude of contractions. 4. The Ba(2+)-induced contractions were inhibited by EDTA, verapamil and diltiazem, but were not modified by sodium nitroprusside. The Ca(2+)-induced contractions were reduced by verapamil and diltiazem. 5. Our results show that Mn2+ and Zn2+ behave as inhibitors of sheep duodenum motility. In contrast, Ba2+ and Ca2+ stimulate motility. It is suggested that Ba2+ can penetrate the cells through voltage-dependent Ca2+ channels and behave as a partial substitute for Ca2+.

Animals↗

PubMed1997

Role of central interleukin-1 beta in gastrointestinal motor disturbances induced by lipopolysaccharide in sheep.

Cytokines are involved in the symptoms of the acute phase response induced by infectious diseases in humans as well as in animals, and interleukin-1 beta (IL-1 beta) has a pivotal role in these changes. The role of central IL-1 beta in the gastrointestinal hypomotility and fever evoked by intravenous administration of lipopolysaccharide (LPS) and the mechanisms involved, were investigated in sheep as an experimental model. LPS (0.1 microgram/kg, intravenously) induced gastrointestinal hypomotility and fever that were significantly reduced by prior intracerebroventricular administration of IL-1 receptor antagonist protein (IL-1ra, 2 micrograms/kg). The effects of LPS were mimicked by intracerebroventricular IL-1 beta (50 ng/kg), whereas IL-1 beta injected intravenously at the same dose only caused a slight and transient fever without modifying the gastrointestinal motility. Prior intracerebroventricular administration of the cyclooxygenase inhibitor indomethacin (100 micrograms/kg) but not the corticotropin-releasing factor (CRF) receptor antagonist alpha-helical CRF9-41 (5 micrograms/kg) blocked all effects by both LPS and IL-1 beta. These results suggest that in sheep, LPS induces digestive motor disturbances through a central release of IL-1 beta and prostaglandins.

Animals↗

PubMed1997

Evidence for the involvement of 5-HT4 receptors in the 5-hydroxytryptamine-induced pattern of migrating myoelectric complex in sheep.

1. The effects induced by 5-hydroxytryptamine (5-HT) on gastrointestinal myoelectric activity in conscious sheep were recorded through electrodes chronically implanted and analysed by computer. The 5-HT receptors and the cholinergic neuronal pathways involved in these actions were investigated. 2. The intravenous (i.v.) administration of 5-HT (2, 4 and 8 micrograms kg-1 min-1, 5 min) induced an antral inhibition concomitant with a duodenal activity front that migrated to the jejunum, followed by a period of intestinal inactivity. This myoelectric pattern closely resembled that observed in the phases III and I of the migrating myoelectric complex (MMC) in sheep. The 0.5 microgram kg-1 min-1 dose evoked the same pattern in only two out of the six animals used. Likewise, the 1 microgram kg-1 min-1 dose similarly affected four of the six animals. In addition, a transient stimulation was observed in the antrum and jejunum when the two highest doses were used. 3. The 5-HT1 antagonist, methiothepin (0.1 mg kg-1), the 5-HT2 antagonists, ritanserin (0.1 mg kg-1) and ketanserin (0.3 mg kg-1), the 5-HT3 antagonists, granisetron (0.2 mg kg-1) and ondansetron (0.5 mg kg-1), as well as the 5-HT4 antagonist, GR113808 (0.2 mg kg-1), did not modify the spontaneous gastrointestinal myoelectric activity. However, the cholinoceptor antagonists, atropine (0.2 mg kg-1) and hexamethonium (2 mg kg-1), inhibited gastrointestinal activity. 4. When these antagonists were injected i.v. 10 min before 5-HT (2 or 4 micrograms kg-1 min-1, 5 min), only GR113808, atropine and hexamethonium were able to modify the 5-HT-induced actions, all of them being completely blocked by the three antagonists. 5. Our data show that 5-HT initiates a MMC-like pattern in the gastrointestinal area in sheep through 5-HT4 receptors. Furthermore, these actions are mediated by cholinergic neural pathways involving muscarinic and nicotinic receptors. However, our results do not indicate a role for either 5-HT1, 5-HT2 or 5-HT3 receptors in the 5-HT-induced effects.

Animals↗

PubMed1997

Pamidronate and biochemical markers of bone turnover.

We have examined the response of different biochemical bone turnover markers to intravenous pamidronate administration (15 mg for 5 days) in 14 patients with Paget's disease, on days 8, 15 and 30 after pamidronate treatment. Urinary parameters of bone resorption, free pyridinolines (Pyr) and hydroxyproline (OHP), as well as serum tartrate-resistant acid phosphatase (TRAP) were measured. Two serum biochemical osteoblastic markers, alkaline phosphatase (AP) and osteocalcin (OC), were also analysed. In addition, ionic calcium (Ca2+) was measured in blood, and parathyroid hormone and calcitriol were measured in serum. All the biochemical markers of bone resorption tested decreased throughout the study. TRAP levels decreased slowly, meanwhile Pyr decreased maximally, below OHP values on day 8. However, the latter were lowest and were lower than those of Pyr on days 15 and 30. AP serum values also decreased during the study. Conversely, OC serum levels increased on days 8 and 15, decreasing to baseline levels on day 30. Ca2+ blood levels decreased while PTH plasma levels increased at all times during the period studied. Calcitriol serum levels increased on day 15. In conclusion, intravenous pamidronate administration was found to modify several biochemical parameters of bone turnover, including Pyr. Moreover, the changes in these parameters were different in intensity and "time course" during the study.

Acid Phosphatase↗

PubMed1996

CYP2D6 genotypes in Spanish women with breast cancer.

Wild type and three mutated alleles of the polymorphic CYP2D6 gene were studied in genomic DNA samples from 187 women with breast carcinoma and 151 healthy women by a mutation-specific polymerase chain reaction. The prevalence of the enzyme-inactivating CYP2D6(B) allele was higher among patients (18.2%) than in controls (11.6%; OR = 1.7; 95% c.i. = 1.14-3.13; P = 0.018). This excess was more marked in postmenopausal patients (19.8%, P = 0.0086) and in patients with non-ductal infiltrating carcinomas (25.8%, P = 0.003). The percentage of carriers of only one active gene (heterozygote extensive metabolizers) was higher in patients (31% vs. 19.9%; OR = 1.81; 95% c.i. = 1.06-3.11; P = 0.02). The CYP2D6(B)-carrier state may be related to a greater risk of breast cancer in women.

Adult↗

PubMed1996

Effect of motilin, somatostatin and bombesin on gastroduodenal myoelectric activity in sheep.

The effects of motilin, erythromycin, somatostatin and bombesin on antroduodenal myoelectric activity were investigated in conscious sheep. Myoelectric recordings were obtained from electrodes chronically implanted on the antrum and duodenal bulb. Peptides or erythromycin were infused intravenously (i.v.) during 5 min. Antagonists were injected i.v. as a bolus. Neither motilin (2.5-80 ng/kg/min) nor erythromycin (2-16 micrograms/kg/min) modified the antroduodenal myoelectric activity, although a single bolus of these compounds (250 ng/kg and 50 micrograms/kg respectively) increased the antral activity. Somatostatin at 5 ng/kg/min induced a decrease in the myoelectric activity of antrum and duodenum. However, doses of 10 to 40 ng/kg/min evoked a duodenal phase III-like activity with a subsequent quiescence period and a concomitant inhibition of the antral activity. These effects were reproduced by bombesin (2.5 to 40 ng/kg/min). Furthermore, an initial increase in the myoelectric activity and in the frequency of slow waves were recorded in the antrum when the highest doses were used. On the other hand, atropine (0.2 mg/kg) or hexamethonium (2 mg/kg) caused a long-lasting inhibition of antroduodenal myoelectric activity. These cholinergic antagonists abolished the effects induced by somatostatin (20 ng/kg/min) but not those evoked by bombesin but not motilin are putative modulators of the migrating myoelectric complex (MMC) in sheep. Moreover, a cholinergic neural pathway is involved in the somatostatin but not in the bombesin-induced effects.

Animals↗

PubMed1996

Involvement of somatostatin, bombesin and serotonin in the origin of the migrating myoelectric complex in sheep.

Antroduodenal myoelectric activity was recorded in conscious sheep by electrodes chronically implanted in the muscular wall. Furthermore, plasma immunoreactive (i.r.) motilin, somatostatin and bombesin concentrations were determined by RIA. The intravenous infusion of somatostatin (20 ng/kg/min), bombesin (10 ng/kg/min) or serotonin (5-HT, 4 micrograms/kg/min) for 5 min, induced a duodenal myoelectric activity front followed by a period of quiescence. These duodenal events were concomitant with an antral inhibition. This pattern resembled that observed in a spontaneous migrating myoelectric complex (MMC) in sheep. Bombesin and 5-HT evoked an additional and transient increase in antral activity simultaneously with the duodenal activity front. On the other hand, plasma i.r. motilin levels did not show any fluctuations during spontaneous MMC cycles or after somatostatin, bombesin or 5-HT infusions. Likewise, plasma i.r. bombesin levels remained unchanged during spontaneous MMC or after administration of somatostatin. However, 5-HT -induced duodenal activity fronts were closely associated with a sharp peak in plasma i.r. bombesin. Finally, plasma i.r. somatostatin concentrations rose at the end of spontaneous phase III and peaked in phase I. A similar pattern of somatostatin release in plasma was found while the duodenal activity front and quiescence period developed after either 5-HT or bombesin infusions. These results do not indicate a role for motilin in the control of MMCs in sheep, although a definitive conclusion cannot be drawn until synthetic sheep motilin is available. However, our data suggest that somatostatin and bombesin-like peptides as well as 5-HT, acting in a coordinated manner, could be involved in the regulation of cyclical antroduodenal motor events in sheep.

Animals↗

PubMed1996

Effect of motilin on gastrointestinal myoelectric activity in conscious rabbits.

Gastrointestinal myoelectric activity was investigated in conscious rabbits with chronically implanted electrodes. As rabbit stomach is never empty, food was removed 1 h before the beginning of recordings. Propagated activity fronts spontaneously started in the jejunum without associated changes in the antroduodenal area. Intravenous administration of either motilin (600-1500 ng/kg) or erythromycin (5-50 micrograms/kg) did not modify antral activity, but simultaneously increased duodenal and jejunal activity in a dose-dependent manner. Spontaneous and induced jejunal activity fronts showed some similarities. However, those induced did not propagate and were not followed by a quiescence period. The effects of motilin (900 ng/kg) and erythromycin (25 micrograms/kg) were resistant to atropine (0.5 mg/kg), hexamethonium (2 mg/kg), or ondansetron (0.5 mg/kg). These results suggest that motilin is not a physiological modulator of the migrating myoelectric complex (MMC) in rabbits. Moreover, neither cholinergic nor 5-HT3 receptors are involved in either motilin or erythromycin-induced actions.

Animals↗

PubMed1996

Myoelectrical activity of the gastrointestinal tract of sheep analysed by computer.

The myoelectrical activity of several sections of the digestive tract of sheep has been studied as an estimation of the gastrointestinal motility. Nickel/chromium electrodes were implanted chronically in the reticulum, rumen, omasum, antrum and duodenum. The myoelectrical signals were then recorded simultaneously and stored in a computer which calculated the integrated activity, duration and period (interval) of each separate reticuloruminal spike burst and the integrated activity (over one minute intervals) in the omasum, abomasum and duodenum. The different electromyographic parameters were standardised in sheep during a period of non-ingestion (resting period), and the physiological changes in these parameters associated with rumination and feeding were measured. The main effect induced by rumination was an increase in the myoelectrical parameters in the reticulum. Feeding enhanced the total activity in all regions studied. In the reticulorumen this increase was due to a rise in the frequency of the spike bursts, although there was a decrease in the integrated activity and duration of each individual spike burst.

Animals↗