Aim: To develop and validate a system that can wirelessly acquire gastric slow waves and deliver electrical pulses to the stomach. Materials & methods: The system is composed of a front-end and a back-end unit connected to a computer, which runs a custom-made graphical user interface. The system was validated on benchtop and in vivo studies. Results: Benchtop validation showed an appropriate frequency response to acquire slow waves. Moreover, the system was able to deliver electrical pulses at amplitudes up to ±10 mA. Slow wave activity recorded from the stomach of rats was in the range of approximately five cycles per minute (cpm). Pulses delivered to the stomach of a rat every 15 s and reduced the activity to 4 cpm during the stimulation period. Conclusion: This study reports the first wireless system and methodology that can be used to acquire slow waves and deliver electrical stimulation to the stomach of small freely behaving animals.

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Background: Gastrointestinal (GI) symptoms in heart failure (HF) patients are associated with increased morbidity and mortality. We hypothesized that HF reduces bioelectrical activity underlying peristalsis. In this study, we aimed to establish a method to capture and analyze slow waves (SW) in the small intestine in mice with HF. Methods: We established a model of HF secondary to coronary artery disease in mice overexpressing tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells. The myoelectric activity was recorded from the small intestine in live animals under anesthesia. The low-and high-frequency components of SW were isolated in MATLAB and compared between the control (n = 12) and eTNAP groups (n = 8). Ckit-positive interstitial cells of Cajal (ICC) and Pgp9.5-positive myenteric neurons were detected by immunofluorescence. Myenteric ganglia were assessed by hematoxylin and eosin (H&E) staining. Results: SW activity was successfully captured in vivo, with both high-and lowfrequency components. Low-frequency component of SW was not different between endothelial TNAP (eTNAP) and control mice (mean[95%

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