Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, United States.
Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
Am J Physiol Gastrointest Liver Physiol. 2024 Dec 1;327(6):G765-G782. doi: 10.1152/ajpgi.00033.2024. Epub 2024 Aug 27.
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 () 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 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. 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.
胃蠕动受电“慢波”控制，通常假定这些慢波从胃近端向远端（顺行传播）以对称环的形式传播。尽管已经观察到替代的慢波模式与胃疾病相关，但它们的机制以及它们如何改变收缩仍未得到充分研究。光学机电映射是心脏电生理学中的一个新兴领域，可同时成像电生理和机械生理。在这里，我们将这项技术应用于活体猪胃。手术暴露胃后，通过胃网膜右动脉注射一种将膜电位（）转换为荧光的荧光染料（di-4-ANEQ(F)PTEA）。通过 LED 激发荧光，并使用一个或两个 256×256 像素的相机进行成像。使用基于标记的运动跟踪方法和激发比测量法校正运动伪影，该方法消除了共模伪影。跟踪标记的位移还使胃变形得以测量。我们通过与替代非光学技术的对比验证了电激活和形态的检测。在我们的数据中，通常存在非顺行的慢波以及胃前壁和后壁之间的传播方向差异。然而，假手术实验表明这些是动物准备的特征，而不是光学映射的伪影。在证明该方法能力的实验中，我们发现复极化并不总是在激活“波前”之后的固定时间发生，这可能是心律失常的一个因素。顺行和非顺行传播之间的收缩强度和电激活与收缩之间的潜伏期存在差异。总之，同时成像电生理和机械活动的光学机电映射使我们能够探索正常和异常胃生理的新问题。本文介绍了一种在麻醉、开腹猪中同时成像胃电生理和机械功能的新方法。我们通过观察沿收缩强度、空间分布和方向传播的慢波去极化和复极化来证明这一点。此外，我们观察到在这种动物准备中，慢波通常不会从胃近端向远端传播，并且在前壁和后壁之间经常不对称。
