| Splenic neurohormonal modulation of mesenteric vascular tone. | |
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MedLine Citation:
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PMID: 22198012 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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In portal hypertension (PH), development of a hyperdynamic circulation is preceded by transient mesenteric vasoconstriction. PH increases splenic venous outflow pressure. We hypothesized that this causes direct reflex activation of mesenteric vasoconstrictor nerves and splenorenal reflex-mediated activation of the renin-angiotensin system. In anaesthetized male rats, we measured mesenteric efferent nerve activity and mesenteric vascular conductance after selectively elevating splenic venous pressure by partial splenic vein occlusion (SVO). Partial SVO raised splenic venous pressure (4.8±0.4 mmHg to 24.1±0.3 mmHg; n=18) and induced a significant increase in mesenteric efferent nerve activity (23.2±3.3 to 31.6±3.5 spikes/sec; n=11); this response was abolished by prior splenic denervation (32.4±2.4 to 31.2±1.6 spikes/sec; n=7). Mesenteric vascular conductance (MVC), the ratio of superior mesenteric artery blood flow to mean arterial pressure, fell upon SVO (ΔMVC= -0.0120±0.0014 mL.min(-1)mmHg(-1), p<0.05, n=10). This was attenuated by splenic denervation (ΔMVC= -0.0044±0.0018 mL.min(-1)mmHg(-1), p<0.05, n=8), but unaffected by mesenteric denervation (ΔMVC= -0.0145±0.0020 mL.min(-1)mmHg(-1), n=6) or bilateral renal denervation (ΔMVC= -0.0106±0.0021 mL.min(-1)mmHg(-1), n=5). Localized blockade of mesenteric vascular angiotensin II type I (AT1) receptors significantly attenuated the response (ΔMVC= -0.0058±0.0017 mL.min(-1)mmHg(-1), p<0.05, n=5), whereas blockade of both AT1 and α1 adrenergic receptors caused a significant increase in mesenteric conductance (ΔMVC= +0.0033±0.0010 mL.min(-1)mmHg(-1), p<0.05, n=6). Our evidence suggests that increased splenic venous outflow pressure reflexly activates adrenergic/angiotensinergic mesenteric nerves, vasodilator mesenteric nerves, and the renin-angiotensin system. We propose that obstruction to splenic venous outflow, such as would normally accompany portal hypertension, induces reflex mesenteric vasoconstriction independently of the increase in portal venous pressure. |
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Authors:
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Shereen M Hamza; Susan Kaufman |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-12-23 |
Journal Detail:
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Title: Experimental physiology Volume: - ISSN: 1469-445X ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2011-12-26 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9002940 Medline TA: Exp Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1 University of Mississippi Medical Center; |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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