Sympathetic activation and vasoregulation in response to carbohydrate ingestion in patients with congestive heart failure.
BACKGROUND
In normal individuals, carbohydrate ingestion increases sympathetic vasoconstrictor activity but causes net vasodilatation in the same vascular bed. This study quantified the effects of carbohydrate ingestion on muscle sympathetic nerve activity (MSNA) and vasoregulation in patients with congestive heart failure (CHF). We hypothesized that high resting levels of MSNA in patients with CHF would blunt further increases in MSNA following carbohydrate ingestion and that their sympathetic activation would restrain vasodilatation.


METHODS
Eleven patients with treated severe CHF and 11 age- and body mass index-matched normal controls (NCs) were studied for 2 hours after a high-carbohydrate meal. MSNA was measured by peroneal microneurography and calf blood flow by venous occlusion plethysmography.


RESULTS
Patients with CHF had higher (P < 0.03) baseline MSNA (67 ± 4.0 bursts/100 beats) than NCs (51 ± 5.8 bursts/100 beats) and lower (P < 0.001) baroreflex sensitivity (2.1 ± 0.58 ms/mm Hg) than NCs (7.4 ± 1.2 ms/mm Hg). Carbohydrate ingestion was associated with a significant increase in MSNA (P < 0.05) and calf blood flow (P < 0.01) with unchanged blood pressure in CHF patients. The magnitude of responses in CHF patients was not significantly different from that in NCs, but vasodilatation was delayed significantly (by 30 minutes).


CONCLUSIONS
Despite considerable resting sympathoexcitation and reduced baroreflex sensitivity, patients with CHF exhibited further increases in MSNA after carbohydrate ingestion, achieving levels similar to those after myocardial infarction. They also had temporally delayed vasodilatation, which could contribute to cachexia and muscle weakness in CHF patients. These observations suggest that high-carbohydrate meals may adversely affect CHF patients via altered autonomic tone and blood-flow patterns.
Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics Health and Therapeutics, LIGHT Laboratories, Clarendon Way, University of Leeds, Leeds, United Kingdom. e.m.scott@leeds.ac.uk
Eleanor M
EM
Scott
John P
JP
Greenwood
Ida
I
Pernicova
Graham R
GR
Law
Stephen G
SG
Gilbey
Mark T
MT
Kearney
David A S G
DA
Mary
D000328:Adult; D000368:Aged; D004040:Dietary Carbohydrates / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D011311:Pressoreceptors / Q000187:drug effects* / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D004040:Dietary Carbohydrates; D014662:Vasoconstrictor Agents