Basal nitric oxide production is impaired in offspring of patients with essential hypertension.
There is considerable evidence that endothelium-dependent nitric oxide (NO)-mediated vasodilatation in response to acetylcholine is impaired in essential hypertension, whereas the endothelium-independent response to sodium nitroprusside is normal. More limited data have suggested that there is also reduced vasoconstriction in response to N(G)-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of basal NO release. As it is not known whether endothelial dysfunction in hypertension, if indeed present, is a cause or consequence of the condition, we have studied the normotensive offspring of parents with essential hypertension. Both basal and stimulated vascular responses were examined in 12 normotensive offspring [mean age (+/-S.E.M.) 26.1+/-1.4 years] of parents with essential hypertension and compared with those in 12 age-matched offspring (mean age 25.6+/-1.1 years) of normotensive subjects. Forearm blood flow was measured simultaneously in both arms by venous occlusion plethysmography, both at baseline and during intra-arterial brachial infusion of increasing doses of acetylcholine, sodium nitroprusside, noradrenaline and L-NMMA. There were no significant differences between the groups in the responses to acetylcholine, sodium nitroprusside or noradrenaline. In contrast, the vasoconstrictor response to L-NMMA was significantly blunted in the offspring of hypertensive parents compared with that in the offspring of normotensive parents (P=0.005). Thus endothelial dysfunction, as demonstrated by impaired basal production of NO, is present in subjects at high risk of essential hypertension, and does not occur simply as a consequence of the condition.
Sir George E. Clark Metabolic Unit, Royal Victoria Hospital, Belfast BT12 6BA, Northern Ireland, U.K.
A S
AS
McAllister
A B
AB
Atkinson
G D
GD
Johnston
D R
DR
Hadden
P M
PM
Bell
D R
DR
McCance
D000109:Acetylcholine / Q000494:pharmacology; D000328:Adult; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010991:Plethysmography; D012039:Regional Blood Flow / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000109:Acetylcholine; D009638:Norepinephrine