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Increasing dietary salt intake alone does not affect chronic levels of renal sympathetic activity or the responses to stressful stimuli in the rabbit
Author(s) -
McBryde Fiona D,
Barrett Carolyn J,
Guild SarahJane,
Osborn John W,
Van Vliet Bruce,
Malpas Simon C
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.738.8
Subject(s) - medicine , endocrinology , chronic stress , blood pressure , sympathetic activity , sympathetic nervous system , heart rate , stimulation , cardiology
The importance of dietary salt in the development of hypertension has long been a source of controversy. Recent studies have suggested the combination of high salt and angiotensin II infusion may be increasing sympathetic drive, however, the effect of a change in dietary salt alone is unclear. We have used telemetry to chronically record renal sympathetic nervous activity (RSNA), arterial pressure (MAP) and heart rate (HR) in 7 New Zealand White rabbits for either 10 days of normal salt diet (0.6g/kg/day NaCl; control) or 5 days prior to and following an increase in salt intake (3g/kg/day; SALT). MAP, HR and RSNA in the SALT group were not significantly different from control either during the baseline period (83±7 mmHg; 240±9bpm; 11±2n.u.) or during high salt (87±9mmHg; 228±9bpm; 12±2n.u.). The responses to common stressful stimuli were also recorded in both groups of animals. Compared to at rest in home cage, being contained in a box, being handled and nasopharyngeal stimulation caused graded increases in MAP (81±4mmHg; 103±6mmHg; 110±5mmHg; 133±8mmHg respectively), HR (223±16bpm; 241±22bpm; 240±17bpm; 29±6bpm) and RSNA (6.4±1nu; 9.6±2nu; 26.2±6nu; 100nu). Stress responses in SALT animals were similar to control. We conclude that a high salt diet alone does not impact on chronic sympathetic drive or the acute responsiveness to stress in rabbits. Supported by the New Zealand Health Research Council.