Haley N Patton, Hanyu Zhang, Garrett A Wood, Bijay Guragain, Nipuni D Nagahawatte, Linley A Nisbet, Leo K Cheng, Gregory P Walcott, Jack M Rogers
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Fluorescence was excited by LEDs and imaged with one or two 256 × 256 pixel cameras. Motion artifact was corrected using a marker-based motion-tracking method and excitation ratiometry, which cancels common-mode artifact. Tracking marker displacement also enabled gastric deformation to be measured. We validated detection of electrical activation and <i>V</i><sub>m</sub> morphology against alternative nonoptical technologies. Nonantegrade slow waves and propagation direction differences between the anterior and posterior stomach were commonly present in our data. However, sham experiments suggest they were a feature of the animal preparation and not an artifact of optical mapping. In experiments to demonstrate the method's capabilities, we found that repolarization did not always follow at a fixed time behind activation \"wavefronts,\" which could be a factor in dysrhythmia. 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引用次数: 0
摘要
胃蠕动受电 "慢波 "支配,一般假定慢波以对称环形方式从胃近端向远端传播(前向传播)。虽然另类慢波模式与胃部疾病有关,但其机制及其如何改变收缩仍未得到充分研究。光学机电图谱是心脏电生理学的一个新兴领域,可同时对电生理学和机械生理学进行成像。在这里,我们将这一技术应用于体内猪胃。手术暴露胃部,通过右胃外膜动脉注入能转导膜电位(Vm)的荧光染料(di-4-ANEQ(F)PTEA)。荧光由 LED 激发,并用一台或两台 256x256 像素相机成像。运动伪影通过基于标记的运动跟踪方法和激发比率法进行校正,从而消除共模伪影。跟踪标记物位移还能测量胃变形。我们对照其他非光学技术对电激活和 Vm 形态的检测进行了验证。在我们的数据中,前胃和后胃之间普遍存在非后向慢波和传播方向差异。然而,假实验表明它们是动物制备的一个特征,而不是光学绘图的伪影。在证明该方法能力的实验中,我们发现再极化并不总是在激活 "波前 "后的固定时间进行,这可能是导致心律失常的一个因素。收缩强度和电激活与收缩之间的潜伏期在逆行传播和非逆行传播之间存在差异。总之,光学机电绘图可同时对电活动和机械活动进行成像,从而探索有关正常和异常胃生理的新问题。
Simultaneous optical imaging of gastric slow waves and contractions in the in vivo porcine stomach.
Gastric peristalsis is governed by electrical "slow waves" generally assumed to travel from proximal to distal stomach (antegrade propagation) in symmetric rings. Although alternative slow-wave patterns have been correlated with gastric disorders, their mechanisms and how they alter contractions remain understudied. Optical electromechanical mapping, a developing field in cardiac electrophysiology, images electrical and mechanical physiology simultaneously. Here, we translate this technology to the in vivo porcine stomach. Stomachs were surgically exposed and a fluorescent dye (di-4-ANEQ(F)PTEA) that transduces the membrane potential (Vm) was injected through the right gastroepiploic artery. Fluorescence was excited by LEDs and imaged with one or two 256 × 256 pixel cameras. Motion artifact was corrected using a marker-based motion-tracking method and excitation ratiometry, which cancels common-mode artifact. Tracking marker displacement also enabled gastric deformation to be measured. We validated detection of electrical activation and Vm morphology against alternative nonoptical technologies. Nonantegrade slow waves and propagation direction differences between the anterior and posterior stomach were commonly present in our data. However, sham experiments suggest they were a feature of the animal preparation and not an artifact of optical mapping. In experiments to demonstrate the method's capabilities, we found that repolarization did not always follow at a fixed time behind activation "wavefronts," which could be a factor in dysrhythmia. Contraction strength and the latency between electrical activation and contraction differed between antegrade and nonantegrade propagation. In conclusion, optical electromechanical mapping, which simultaneously images electrical and mechanical activity, enables novel questions regarding normal and abnormal gastric physiology to be explored.NEW & NOTEWORTHY This article introduces a novel method for imaging gastric electrophysiology and mechanical function simultaneously in anesthetized, open-abdomen pigs. We demonstrate it by observing propagating slow-wave depolarization and repolarization along with the strength, spatial distribution, and direction of contractions. In addition, we observe that in this animal preparation, slow waves often do not propagate from the proximal to distal stomach and are frequently asymmetric between the anterior and posterior sides of the stomach.
期刊介绍:
The American Journal of Physiology-Gastrointestinal and Liver Physiology publishes original articles pertaining to all aspects of research involving normal or abnormal function of the gastrointestinal tract, hepatobiliary system, and pancreas. Authors are encouraged to submit manuscripts dealing with growth and development, digestion, secretion, absorption, metabolism, and motility relative to these organs, as well as research reports dealing with immune and inflammatory processes and with neural, endocrine, and circulatory control mechanisms that affect these organs.