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Altered responsiveness of the kidney to activation of the renal nerves in fat-fed rabbits
journal contribution
posted on 2009-01-01, 00:00 authored by S Michaels, G Eppel, S Burke, G Head, James ArmitageJames Armitage, J Carrol, S Malpas, R EvansWe tested whether mild adiposity alters responsiveness of the kidney to activation of the renal sympathetic nerves. After rabbits were fed a high-fat or control diet for 9 wk, responses to reflex activation of renal sympathetic nerve activity (RSNA) with hypoxia and electrical stimulation of the renal nerves (RNS) were examined under pentobarbital anesthesia. Fat pad mass and body weight were, respectively, 74% and 6% greater in fat-fed rabbits than controls. RNS produced frequency-dependent reductions in renal blood flow, cortical and medullary perfusion, glomerular filtration rate, urine flow, and sodium excretion and increased renal plasma renin activity (PRA) overflow. Responses of sodium excretion and medullary perfusion were significantly enhanced by fat feeding. For example, 1 Hz RNS reduced sodium excretion by 79 ± 4% in fat-fed rabbits and 46 ± 13% in controls. RNS (2 Hz) reduced medullary perfusion by 38 ± 11% in fat-fed rabbits and 9 ± 4% in controls. Hypoxia doubled RSNA, increased renal PRA overflow and medullary perfusion, and reduced urine flow and sodium excretion, without significantly altering mean arterial pressure (MAP) or cortical perfusion. These effects were indistinguishable in fat-fed and control rabbits. Neither MAP nor PRA were significantly greater in conscious fat-fed than control rabbits. These observations suggest that mild excess adiposity can augment the antinatriuretic response to renal nerve activation by RNS, possibly through altered neural control of medullary perfusion. Thus, sodium retention in obesity might be driven not only by increased RSNA, but also by increased responsiveness of the kidney to RSNA.
History
Journal
Renal physiologyVolume
296Pagination
1889 - 1896Publisher
Biomedical Information Project, University of SheffieldLocation
Sheffield, Eng.Publisher DOI
ISSN
0300-3434Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2009, Biomedical Information Project, University of SheffieldUsage metrics
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Science & TechnologyLife Sciences & BiomedicinePhysiologyhypertensionhypoxiakidney circulationobesitykidney medullarenal sympathetic nervesrenin-angiotensin systemsodium excretionINTRARENAL BLOOD-FLOWSYMPATHETIC NEURAL ACTIVATIONOBESITY-INDUCED HYPERTENSIONOXIDATIVE STRESSANGIOTENSIN-IIPRESSURE-NATRIURESISNITRIC-OXIDEDIFFERENTIAL CONTROLNERVOUS-SYSTEMRESPONSES
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