HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 565/1/269    most recent jphysiol.2005.083147v2 jphysiol.2005.083147v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Brookes, Z. L. S. Articles by Kaufman, S. Search for Related Content PubMed PubMed Citation Articles by Brookes, Z. L. S. Articles by Kaufman, S.

¹ Department of Physiology, University of Alberta, Edmonton, Alberta, Canada, T6G 2S2

We developed a novel model using fluorescent intravital microscopy to study the effect of atrial natriuretic peptide (ANP) on the extrasplenic microcirculation. Continuous infusion of ANP into the splenic artery (10 ng min^–1 for 60 min) of male Long–Evans rats (220–250 g, n= 24) induced constriction of the splenic arterioles after 15 min (–7.2 ± 6.6% from baseline diameter of 96 ± 18.3 µm, mean ±S.E.M.) and venules (–14.4 ± 4.0% from 249 ± 25.8 µm; P < 0.05). At the same time flow did not change in the arterioles (from 1.58 ± 0.34 to 1.27 ± 0.27 ml min^–1), although it decreased in venules (from 1.67 ± 0.23 to 1.15 ± 0.20 ml min^–1) and increased in the lymphatics (from 0.007 ± 0.001 to 0.034 ± 0.008 ml min^–1; P < 0.05). There was no significant change in mean arterial pressure (from 118 ± 5 to 112 ± 5 mmHg). After continuous ANP infusion for 60 min, the arterioles were dilated (108 ± 16 µm, P < 0.05) but the venules remained constricted (223 ± 24 µm). Blood flow decreased in both arterioles (0.76 ± 0.12 ml min^–1) and venules (1.03 ± 0.18 ml min^–1; P < 0.05), but was now unchanged from baseline in the lymphatics (0.01 ± 0.001 ml min^–1). This was accompanied by a significant decrease in MAP (104 ± 5 mmHg; P < 0.05). At 60 min, there was macromolecular leak from the lymphatics, as indicated by increased interstitial fluorescein isothiocyanate–bovine serum albumin fluorescence (grey level: 0 = black; 255 = white; from 55.8 ± 7.6 to 71.8 ± 5.9, P < 0.05). This study confirms our previous proposition that, in the extrasplenic microcirculation, ANP causes greater increases in post- than precapillary resistance, thus increasing intrasplenic capillary hydrostatic pressure (P_c) and fluid efflux into the lymphatic system. Longer-term infusion of ANP also increases Pc, but this is accompanied by increased ‘permeability’ of the extrasplenic lymphatics, such that fluid is lost to perivascular third spaces.

(Received 13 January 2005; accepted after revision 15 February 2005; first published online 17 February 2005)
Corresponding author Z. L. S. Brookes: University of Sheffield, Academic Unit of Anaesthesia, K Floor, Royal Hallamshire Hospital, Sheffield S10 2JF, UK. Email: zoe.brookes{at}sheffield.ac.uk

This article has been cited by other articles:

				K. Moncrief and S. Kaufman Splenic baroreceptors control splenic afferent nerve activity Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2006; 290(2): R352 - R356. [Abstract] [Full Text] [PDF]