IleumSuperior ColliculiVena Cava, SuperiorMesenteric Artery, SuperiorGuinea PigsSuperior Vena Cava SyndromeMyenteric PlexusIleal DiseasesMuscle, SmoothIleitisSuperior Cervical GanglionIntestine, SmallIntestinal MucosaMuscle ContractionIleal NeoplasmsIntestinesIntestinal AbsorptionColonDuodenumGastrointestinal MotilityDiphenylacetic AcidsAtropineIleocecal ValveElectric StimulationSwineTime FactorsAcetylcholineMagnetic Resonance ImagingTreatment OutcomeMesenteric Vascular OcclusionRabbitsHexamethonium CompoundsLaryngeal NervesSuperior Sagittal SinusGanglia, SympatheticCecumPeristalsisMesenteric VeinsGastrointestinal ContentsIntestinal Diseases