Variations in gastric emptying of liquid elicited by acute blood volume changes in awake rats

Gondim, Francisco de Assis Aquino; Oliveira, G. R. De; Graça, José Ronaldo Vasconcelos da; Cavalcante, Diane Isabelle Magno; Souza, Miguel Angelo N.; Santos, Armênio Aguiar dos; Rola, Francisco H.

doi:10.1590/s0100-879x1998000700013

Cited by 11 publications

(12 citation statements)

References 16 publications

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“…This BV overload protocol has been extensively utilized in our previous studies, both in anaesthetized rats and in awake rats 6 . 8 –10 For investigating neural mechanisms, separate groups of rats were previously submitted to a drug pretreatment or a surgical procedure. In all protocols, the animals were killed at a fixed time interval (10 min) after liquid meal gavage.…”

Section: Methodsmentioning

confidence: 99%

“…The gut seems to react to acute blood volume (BV) imbalances by adjusting the gastrointestinal (GI) motility 1 –10 as well as its permeability to fluid and electrolytes 11…”

Section: Introductionmentioning

confidence: 99%

“…Since these variations on the gastroduodenal flow were verified in anaesthetized animals after invasive surgical procedures, we decided to study the effect of acute BV changes on the GI motility of awake rats: BV expansion delays the gastric emptying (GE) and GI transit of liquid meals while BV retraction accelerates GE rates 9 . 10 …”

Section: Introductionmentioning

confidence: 99%

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Neural mechanisms involved in the delay of gastric emptying of liquid elicited by acute blood volume expansion in awake rats

Gondim

Oliveira

Graça

et al. 1999

Neurogastroenterology Motil

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We have previously reported that acute blood volume expansion in awake rats delays the gastric emptying of a liquid meal, using the phenol red method. In this study we attempted to investigate the neural mechanisms involved in this phenomenon. Blood volume expansion, due to Ringer-bicarbonate infusion up to a volume equivalent to 5% of body weight, decreased the gastric emptying of a liquid meal by half (38.2 +/- 1.8 vs 18.7 +/- 3.2%, P < 0.05). The blood volume expansion effect on gastric emptying of liquid was prevented by separate pretreatments, consisting of subdiaphragmatic vagotomy or i.v. injection of hexamethonium (20 mg kg-1) or yohimbine (3 mg kg-1). Intravenous injection of atropine (0.5 mg kg-1), guanethidine (10 mg kg-1), L-NAME (3 mg kg-1), prazosin (1 mg kg-1) or propranolol (2 mg kg-1) did not prevent the blood volume expansion effect on gastric emptying. Bilateral adrenalectomy or coeliac ganglionectomy were also ineffective. The results indicate that blood volume expansion decreases gastric emptying of liquid through vagal-dependent pathways, sensitive to hexamethonium and yohimbine. Evidence for the participation of the peripheral sympathetic nervous system was not found.

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Section: Methodsmentioning

confidence: 99%

“…The gut seems to react to acute blood volume (BV) imbalances by adjusting the gastrointestinal (GI) motility 1 –10 as well as its permeability to fluid and electrolytes 11…”

Section: Introductionmentioning

confidence: 99%

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Neural mechanisms involved in the delay of gastric emptying of liquid elicited by acute blood volume expansion in awake rats

Gondim

Oliveira

Graça

et al. 1999

Neurogastroenterology Motil

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“…Moreover, we have shown that blood volume redistribution modifies gastrointestinal motor behavior (14,40). Taken together, our hypothesis is that the opening of an AV fistula impels the circulation to a hyperkinetic status, which affects the gut motor behavior in virtue of hemodynamic adjustments and multiple neurohumoral changes.…”

mentioning

confidence: 66%

Aortocaval fistula delays gastric emptying of liquid test meal in awake rats

Silva

Palheta

Oliveira

et al. 2013

American Journal of Physiology-Heart and Circulatory Physiology

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Silva MT, Palheta RC Jr, Oliveira FG, de Lima JB, AntunesRodrigues J, Oliveira RB, Magalhães PJ, Santos AA. Aortocaval fistula delays gastric emptying of liquid test meal in awake rats. Am J Physiol Heart Circ Physiol 304: H1397-H1405, 2013. First published March 15, 2013 doi:10.1152/ajpheart.00827.2012.-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 Ͻ 0.05) heart rate, central venous pressure, and cardiac output values and increased (P Ͻ 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. arteriovenous fistula; gastrointestinal motility; hyperkinetic circulation; intestinal transit; natriuretic hormone HYPERKINETIC CIRCULATION IS a systemic condition that may originate from an arteriovenous (AV) fistula, either as a congenital malformation or acquired after invasive procedures (e.g., percutaneous renal biopsy), surgeries (e.g., nephrectomy), or trauma (e.g., stab or gunshot wounds) (11,24). Large AV fistulas are considered a simple and reliable model to elicit congestive heart failure (13). Laboratory animals with an aortocaval fistula (ACF) present hemodynamic and neurohumoral changes that resemble those seen in patients with heart failure, including cardiac hypertrophy (22). These animals have high levels of cardiac output (CO) and mean circulatory filling pressure, in addition to tachycardia, low resistance to blood flow in circulatory vessels, and decreased mean arterial pressure (MAP) (17).As a consequence of inducing such changes, the placement of an AV fistula activates complex neurohumoral mechanisms that may restore hemodynamic homeostasis. During ...

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“…However, this effect was short-lived compared to the delay of intestinal transit, which persisted for at least 50 min after drug administration. Thus, it seems that the sildenafil-induced delay of the intestinal transit results from a direct action of the drug on the gastrointestinal smooth muscle cells, instead of a secondary hemodynamic effect (19). Interestingly, there was almost no retention of the isotope marker in the gastroduodenal stumps of the sildenafil-treated rats.…”

mentioning

confidence: 90%

Sildenafil delays the intestinal transit of a liquid meal in awake rats

Graça¹,

Macedo²,

Palheta³

et al. 2008

Braz J Med Biol Res

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Sildenafil slows down the gastric emptying of a liquid test meal in awake rats and inhibits the contractility of intestinal tissue strips. We studied the acute effects of sildenafil on in vivo intestinal transit in rats. Fasted, male albino rats (180-220 g, N = 44) were treated (0.2 mL, iv) with sildenafil (4 mg/kg) or vehicle (0.01 N HCl). Ten minutes later they were fed a liquid test meal ( 99m 99m 99m 99m 99m technetium-labeled saline) injected directly into the duodenum. Twenty, 30 or 40 min after feeding, the rats were killed and transit throughout the gastrointestinal tract was evaluated by progression of the radiotracer using the geometric center method. The effect of sildenafil on mean arterial pressure (MAP) was monitored in a separate group of rats (N = 14). Data (medians within interquartile ranges) were compared by the Mann-Whitney U-test. The location of the geometric center was significantly more distal in vehicle-treated than in sildenafil-treated rats at 20, 30, and 40 min after test meal instillation (3.3 (3.0-3.6) vs 2.9 (2.7-3.1); 3.8 (3.4-4.0) vs 2.9 (2.5-3.1), and 4.3 (3.9-4.5) vs 3.4 (3.2-3.7), respectively; P < 0.05). MAP was unchanged in vehicletreated rats but decreased by 25% (P < 0.05) within 10 min after sildenafil injection. In conclusion, besides transiently decreasing MAP, sildenafil delays the intestinal transit of a liquid test meal in awake rats. Sildenafil citrate belongs to a class of compounds called phosphodiesterase (PDE) inhibitors. PDEs constitute a family of enzymes that hydrolyze cyclic nucleotides (cyclic adenosine monophosphate and cyclic guanosine monophosphate, cGMP) and play a critical role in the modulation of the second messenger pathway (1). Sildenafil citrate is a selective PDE type 5 inhibitor widely used due to its therapeutic efficacy in human erectile dysfunction and pulmonary hypertension. It effectively blocks the PDE 5-mediated hydrolysis of cGMP inside vascular smooth muscle cells, relaxing the arterioles that supply the corpus cavernosum (2) and the lung parenchyma (3).Sildenafil increases the gastric resistance to injury by non-steroidal anti-inflammatory drugs (4), decreases the distal esophageal peristalsis (5), and inhibits the gastric emptying of test meals both in humans and rats (6,7), and decreases the contractility of isolated duodenal strips (8).Since the gastrointestinal transit rate results from a complex interplay between gastric tonus, distal stomach phasic activity and resistance and propulsion offered by the small intestine (9), we measured the effect of sildenafil on the small bowel intestinal transit of a liquid test meal in awake rats.

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Variations in gastric emptying of liquid elicited by acute blood volume changes in awake rats

Cited by 11 publications

References 16 publications

Neural mechanisms involved in the delay of gastric emptying of liquid elicited by acute blood volume expansion in awake rats

Neural mechanisms involved in the delay of gastric emptying of liquid elicited by acute blood volume expansion in awake rats

Aortocaval fistula delays gastric emptying of liquid test meal in awake rats

Sildenafil delays the intestinal transit of a liquid meal in awake rats

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