Angiotensin II‐induced contractions in human jejunal wall musculature <i>in vitro</i>

Casselbrant, Anna; Olbers, Torsten; Lönroth, Hans; Fändriks, Lars

doi:10.1111/j.1748-1716.2007.01826.x

Cited by 28 publications

(31 citation statements)

References 38 publications

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“…We have recently analysed the pharmacological characteristics of Ang II-induced contractions in isolated rat and human small intestinal muscle preparations. 36,37 It was generally noted that consecutive increases of Ang II concentrations were associated with contractions, usually with maximal response at approximately 10 -7 M. At higher concentrations, the responses tended to fade, which is well known to occur in association with Ang II-induced smooth muscle contractions also in the intestine. 38 The presence of the AT 1 receptor antagonist losartan shifted the dose-response curve to the right, whereas an AT 2 receptor antagonist was without effect.…”

Section: Gi Wall Musculaturementioning

confidence: 99%

“…Interestingly, the muscular activities of the distal oesophagus and the lower oesophageal sphincter are influenced by Ang II via the AT 1 receptor but, as in the small intestine, the AT 2 receptor has no obvious impact on contractile activities. 7,37 Furthermore, in the healthy oesophageal mucosa, both AT 1 and AT 2 receptors are present on the surface squamous epithelium as well as, not that surprisingly, in close relation to blood vessels in deeper parts. 42 The epithelial location of Ang II receptors is intriguing.…”

Section: Potential Clinical Applicationsmentioning

confidence: 99%

“…On the other hand, we found that both AT 1 and AT 2 receptors were located on the myenteric nerves in human tissue, which contrasts with the situation in the guinea pig where only AT 1 receptors have been found to be present. 37,39 A generally proposed viewpoint is that AT 2 receptors counteract effects mediated by AT 1 receptors in various tissues. 40 Such an arrangement has been demonstrated with regard to the rat internal anal sphincter.…”

Section: Gi Wall Musculaturementioning

confidence: 99%

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The angiotensin II type 2 receptor and the gastrointestinal tract

Fändriks

2009

J Renin Angiotensin Aldosterone Syst

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The renin-angiotensin system (RAS) is well known for its vital involvement in body fluid homeostasis and circulation. However, very little research has been devoted to the impact of this regulatory system on the gastrointestinal (GI) system. This is surprising because the GI tract is fundamental for the intake and excretion of fluid and electrolytes (and nutrients), and it accommodates a large proportion of bodily haemodynamics and host defence systems. The RAS is well expressed and active in the GI tract, although the exact roles for the key mediator angiotensin II (Ang II) and its receptors in general, and the type 2 (AT 2 ) receptor in particular, are not completely settled. There are several reports showing Ang II regulation of intestinal fluid and electrolyte transport. For example, mucosaprotective duodenal bicarbonate-rich secretion is inhibited by Ang II via type 1 (AT 1 ) receptor-mediated facilitation of sympathoadrenergic activity, but this secretory process can also be stimulated by Ang II via AT 2 receptors. Novel data from human oesophagus and jejunum suggest that the AT 1 receptor mediates muscular contractions and that the AT 2 receptor regulates epithelial functions. Data are accumulating suggesting involvement of AT 1 and AT 2 receptors in GI inflammation and carcinogenesis. The picture of the RAS and AT 2 receptor in the GI tract is, however, far from complete. Much more basic research is needed with regard to GI pathophysiology before concluding clinical significance and potential applicability of pharmacological interferences with the RAS.

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Section: Gi Wall Musculaturementioning

confidence: 99%

Section: Potential Clinical Applicationsmentioning

confidence: 99%

Section: Gi Wall Musculaturementioning

confidence: 99%

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The angiotensin II type 2 receptor and the gastrointestinal tract

Fändriks

2009

J Renin Angiotensin Aldosterone Syst

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“…The gastrointestinal (GI) tract is also essential for the uptake and excretion of fluids and electrolytes. Specifically, fluid and buffer transport are regulated in the GI system by angiotensin II (AngII) (Jin, Wang, Siragy, Guerrant, & Carey, 1998;Johansson et al, 2001;Levens, 1985) and the AngII receptors (type 1 and 2) that are distributed in the GI tract are important in regulating smooth muscle contraction (Fandriks, 2011;Patten et al, 2005;Spak, Casselbrant, Olbers, Lonroth, & Fandriks, 2008). The presence of AngII in the GI tract has also been linked with Crohn's Disease via NF-kB pathway-mediated inflammation and epithelial fibrosis (Hume & RadfordSmith, 2008) and to GI carcinogenesis (Fandriks, 2011).…”

Section: Significance Of In Vitro Results For In Vivo Efficacymentioning

confidence: 96%

Processed dietary plants demonstrate broad capacity for angiotensin converting enzyme and angiotensin II receptor binding inhibition in vitro

Patten

Abeywardena

Head

et al. 2012

Journal of Functional Foods

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“…Nevertheless, the low ANG II level observed in the present study is consistent with ACF-induced GE delay. In fact, ANG II is considered to have predominantly stimulatory actions on small intestine motility (35).…”

Section: Discussionmentioning

confidence: 99%

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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Angiotensin II‐induced contractions in human jejunal wall musculature in vitro

Abstract: This pharmacological analysis indicates that the contractile action elicited by angiotensin II on jejunal wall musculature is primarily mediated through the angiotensin II type 1 receptor located on the musculature.

Cited by 28 publications

References 38 publications

The angiotensin II type 2 receptor and the gastrointestinal tract

The angiotensin II type 2 receptor and the gastrointestinal tract

Processed dietary plants demonstrate broad capacity for angiotensin converting enzyme and angiotensin II receptor binding inhibition in vitro

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

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