Visceral obesity is characterized by impaired nitric oxide-independent vasodilation.
BACKGROUND
Endothelial dysfunction has been described in obesity. This study examines the impact of visceral obesity on nitric oxide-independent relaxation in the human forearm.


RESULTS
In ten viscerally obese and ten matched controls forearm blood flow (FBF) was measured by venous occlusion plethysmography during intrabrachial infusion of: (1) sodium nitroprusside; (2) bradykinin, before and after inhibition of vasoactive prostaglandins and nitric oxide; (3) potassium; (4) ouabain (Na(+)/K(+)ATPase inhibitor) alone or (5) in combination with BaCl(2)(K(IR)inhibitor). Baseline FBF and endothelium-independent vasodilatation were similar in the two groups. In obese patients, bradykinin-induced increase of FBF was significantly less than in controls (P<0.01). Irrespective of prostaglandins and nitric oxide inhibition, bradykinin response was lower in the viscerally obese. Intrabrachial potassium determined a significantly blunted response (P<0.05). Ouabain caused a similar, moderate decrease in basal FBF in the two groups; the coinfusion of BaCl(2)caused a more intense decline in FBF which was significantly relevant in obese (-24+/-5%, P<0.01).


CONCLUSIONS
In obese patients there is a blunted nitric oxide-independent relaxation determined by a decreased response of inwardly rectifying potassium channels.
Vigili de Kreutzenberg
S
S
Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy.
Kiwanuka
E
E
Tiengo
A
A
Avogaro
A
A
D000328:Adult; D017609:Barium Compounds / Q000494:pharmacology; D001916:Brachial Artery; D001920:Bradykinin / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular; D005542:Forearm / Q000098:blood supply; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology*; D009765:Obesity / Q000503:physiopathology*; D010042:Ouabain / Q000494:pharmacology; D010991:Plethysmography; D011188:Potassium / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D017609:Barium Compounds; D002712:Chlorides; D016861:Cyclooxygenase Inhibitors; D014665:Vasodilator Agents; C024986:barium chloride; D009599:Nitroprusside; D009569:Nitric Oxide; D010042:Ouabain; D019001:Nitric Oxide Synthase; D011188:Potassium; D001920:Bradykinin