On the electrical intestine turbulence induced by temperature changes

Gizzi, Alessio; Cherubini, Christian; Migliori, S; Alloni, Rossana; Portuesi, Rosalba; Filippi, Sandra

doi:10.1088/1478-3975/7/1/016011

Cited by 38 publications

(50 citation statements)

References 84 publications

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“…This is demonstrated in the maps of cycles 10 (30 s after the first map) and 18 (54 s) and in the series of electrograms recorded along the revolving wave front in electrodes [1][2][3][4][5][6][7][8][9][10][11][12][13][14] (Fig. 2, bottom).…”

Section: Resultsmentioning

confidence: 99%

“…An anatomical circuit is potentially much more stable than functional reentries as it revolves in a larger circuit then in functional reentry and propagates in tissues that is more or fully recovered from the previous cycle (26). Indeed, a simulated demonstration of such an arrhythmia was shown recently (6), and it is probably only a matter of time before an actual anatomical reentry is demonstrated in the small intestines (2). Another limitation induced by our dissection is that the length of the small intestine was also restricted.…”

Section: Discussionmentioning

confidence: 99%

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Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

Lammers¹,

Stephen²,

Karam

2012

American Journal of Physiology-Gastrointestinal and Liver Physi

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Lammers WJ, Stephen B, Karam SM. Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats. Am J Physiol Gastrointest Liver Physiol 302: G684 -G689, 2012. First published December 29, 2011; doi:10.1152/ajpgi.00332.2011.-In a few recent studies, the presence of arrhythmias based on reentry and circus movement of the slow wave have been shown to occur in normal and diseased stomachs. To date, however, reentry has not been demonstrated before in any other part of the gastrointestinal system. No animals had to be killed for this study. Use was made of materials obtained during the course of another study in which 11 rats were treated with streptozotocin and housed with age-matched controls. After 3 and 7 mo, segments of duodenum, jejunum, and ileum were isolated and positioned in a tissue bath. Slow wave propagation was recorded with 121 extracellular electrodes. After the experiment, the propagation of the slow waves was reconstructed. In 10 of a total of 66 intestinal segments (15%), a circus movement of the slow wave was detected. These reentries were seen in control (n ϭ 2) as well as in 3-mo (n ϭ 2) and 7-mo (n ϭ 6) diabetic rats. Local conduction velocities and beat-to-beat intervals during the reentries were measured (0.42 Ϯ 0.15 and 3.03 Ϯ 0.67 cm/s, respectively) leading to a wavelength of 1.3 Ϯ 0.5 cm and a circuit diameter of 4.1 Ϯ 1.5 mm. This is the first demonstration of a reentrant arrhythmia in the small intestine of control and diabetic rats. Calculations of the size of the circuits indicate that they are small enough to fit inside the intestinal wall. Extrapolation based on measured velocities and rates indicate that reentrant arrhythmias are also possible in the distal small intestine of larger animals including humans. slow wave; diabetes; wavelength THE SMOOTH MUSCLE LAYER OF the gastrointestinal (GI) tract generates spontaneous electrical activities that are referred to as "slow waves." These slow waves are dependent on the interstitial cells of Cajal in the myenteric plexus (ICC-MY) and are important for maintaining normal GI motility (8, 9).In a recent study, we investigated the propagation of slow waves in a streptozotocin (STZ) model of diabetes in rats. The purpose of that study was to correlate the expected decrease in slow wave propagation with the reported decrease in the census of ICC-MY in the small intestine (8,10,20,30). To our initial surprise, we did not measure a significant decrease in slow wave propagation although there was a reduction in the number of ICC-MY by ϳ50% (10). We concluded from that study that the reduction of ICC-MY was not enough to block slow wave propagation.Further analysis of the propagation in both control and in 3-and 7-mo diabetic rats, however, revealed another unexpected result. In ϳ15% of the segments, slow wave propagation did not originate from one or a few foci (10, 11). Instead, the slow wave was seen to propagate in a circular fashion for relatively long periods of time, whereby the impulse could rotate ...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

Lammers¹,

Stephen²,

Karam

2012

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…The fibers are highly connected within the bundle and with other bundles in order to spread the bio-electrical potentials in the most efficient manner. The resulting structure is a functional syncytium, typical of several electro-active biological tissues, allowing reaction-diffusion processes with associated propagating behaviors 21,22 . Additionally, ML and MC bundles present connecting points enabling correct peristaltic movements.…”

Section: Gi Wall Anatomy and Functionmentioning

confidence: 99%

“…(29) have been calibrated accurately to describe the intestine peristalsis activity 22 . This potential describes an active strain that persists for a certain lapse of time after the electric potential wave crossing, in order to model the duration of the muscle contraction.…”

Section: Active Behavior: Intestine Electrophysiologymentioning

confidence: 99%

Visco-hyperelasticity of Electro-active Soft Tissues

Gizzi¹,

Pandolfi²

2015

Procedia IUTAM

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Elastic-electroactive (EA) media represent a wide range of materials and physical systems sensitive to mechanical forces and electric fields, in which time and temperature dependence are additional recurrent features. The behavior of fiber reinforced active tissues, namely the excitation-contraction coupling, is basically due to the nonlinear interplay between the passive elastic tissue and the active muscular network. The observed macroscopic dynamics derives as the emergent behavior of a complex multiscale architecture spanning several length scales. We present a general theoretical framework for the formulation of constitutive equations for viscous electro-active media. The approach is based on the additive decomposition of the Helmholtz free energy in elastic, viscous and active parts accompanied to the multiplicative decomposition of the deformation gradient in elastic, viscus and active parts. We describe a thermodynamically sound scenario that accounts for geometric and material nonlinearities. We specialize the material model to the behavior of colonic intestine tissue, and simulate the visco-electro-active behavior of the fiber-reinforced wall layers by using the finite element method.

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“…Nevertheless, the basic mechanism governing thermal GIT smooth muscle responses has not been fully investigated in experimental measurements in in vivo and in vitro models. Studies based on physiologically tuned mathematical models have predicted that thermal cooling may induce an electrochemical destabilization of peristaltic activity (29).…”

mentioning

confidence: 99%

Experimental evidence and mathematical modeling of thermal effects on human colonic smooth muscle contractility

Altomare

Gizzi

Guarino

et al. 2014

American Journal of Physiology-Gastrointestinal and Liver Physi

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It has been shown, in animal models, that gastrointestinal tract (GIT) motility is influenced by temperature; nevertheless, the basic mechanism governing thermal GIT smooth muscle responses has not been fully investigated. Studies based on physiologically tuned mathematical models have predicted that thermal inhomogeneity may induce an electrochemical destabilization of peristaltic activity. In the present study, the effect of thermal cooling on human colonic muscle strip (HCMS) contractility was studied. HCMSs were obtained from disease-free margins of resected segments for cancer. After removal of the mucosa and serosa layers, strips were mounted in separate chambers. After 30 min, spontaneous contractions developed, which were measured using force displacement transducers. Temperature was changed every hour (37, 34, and 31°C). The effect of cooling was analyzed on mean contractile activity, oscillation amplitude, frequency, and contraction to ACh (10(-5) M). At 37°C, HCMSs developed a stable phasic contraction (~0.02 Hz) with a significant ACh-elicited mean contractile response (31% and 22% compared with baseline in the circular and longitudinal axis, respectively). At a lower bath temperature, higher mean contractile amplitude was observed, and it increased in the presence of ACh (78% and 43% higher than the basal tone in the circular and longitudinal axis, respectively, at 31°C). A simplified thermochemomechanical model was tuned on experimental data characterizing the stress state coupling the intracellular Ca(2+) concentration to tissue temperature. In conclusion, acute thermal cooling affects colonic muscular function. Further studies are needed to establish the exact mechanisms involved to better understand clinical consequences of hypothermia on intestinal contractile activity.

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On the electrical intestine turbulence induced by temperature changes

Cited by 38 publications

References 84 publications

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

Visco-hyperelasticity of Electro-active Soft Tissues

Experimental evidence and mathematical modeling of thermal effects on human colonic smooth muscle contractility

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