title: Aortocaval fistula delays gastric emptying of liquid test meal in awake rats.
abstract: Arteriovenous anastomoses disrupt cardiovascular and renal homeostasis, eliciting hemodynamic adjustments, resetting the humoral pattern, and inducing cardiac hypertrophy. Because acute circulatory imbalance alters gut motor behavior, we studied the effects of arteriovenous fistula placement on the gastric emptying (GE) of a liquid meal in awake rats. After laparotomy, we created an aortocaval fistula (ACF) by aorta and cava wall puncture with a 21-, 23-, or 26-gauge needle. The ACF was not created in the control group, which underwent sham operation. After 12, 24, or 48 h, mean arterial pressure, heart rate, and central venous pressure were continuously recorded, and cardiac output was estimated by thermal dilution. The rats were then gavage fed a test meal (i.e., phenol red in glucose solution), and fractional dye retention was determined 10, 20, or 30 min later. The effect of prior bleeding on ACF-induced GE delay, the role of neuroautonomic pathways, and changes in plasma hormone levels (i.e., angiotensin II, arginine vasopressin, atrial natriuretic peptide, corticosterone, and oxytocin) were evaluated. When compared with the sham-operated group, ACF rats exhibited arterial hypotension, higher (P < 0.05) heart rate, central venous pressure, and cardiac output values and increased (P < 0.05) gastric dye retention, a phenomenon prevented by bilateral subdiaphragmatic vagotomy and hexamethonium treatment. Pirenzepine also impaired the occurrence of gastric delay in subjects with ACF. In addition to causing hyperkinetic circulation, ACF placement delayed the GE of liquid in awake rats, an effect that likely involves a parasympathetic pathway.
authors.affiliation: Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil.
authors.forename: Moisés T B
authors.initials: MT
authors.lastname: Silva
authors.forename: Raimundo C
authors.initials: RC
authors.lastname: Palheta
authors.forename: Francisca G V
authors.initials: FG
authors.lastname: Oliveira
authors.forename: Juliana B M
authors.initials: JB
authors.lastname: de Lima
authors.forename: José
authors.initials: J
authors.lastname: Antunes-Rodrigues
authors.forename: Ricardo B
authors.initials: RB
authors.lastname: Oliveira
authors.forename: Pedro J C
authors.initials: PJ
authors.lastname: Magalhães
authors.forename: Armênio A
authors.initials: AA
authors.lastname: Santos
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal; D001164:Arteriovenous Fistula / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000502:physiology; D001784:Blood Gas Analysis; D002302:Cardiac Output; D004567:Electrodes, Implanted; D015171:Ganglionectomy; D005746:Gastric Emptying / Q000502:physiology*; D005772:Gastrointestinal Transit / Q000502:physiology; D006728:Hormones / Q000097:blood; D007813:Laparotomy; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000502:physiology; D014628:Vagotomy; D014682:Vena Cava, Inferior
chemical_list: D006728:Hormones; D011978:Receptors, Nicotinic
keywords: arteriovenous fistula; gastrointestinal motility; hyperkinetic circulation; intestinal transit; natriuretic hormone