NITRIC-OXIDE ACTIVITY IN CHILDHOOD HYPERTENSION

Objectives-To investigate nitric oxide (NO) activity in childhood hype rtension using nitrite and nitrate (NOx) concentrations in plasma as a n index of nitric oxide generation. Design-Cross sectional study. Sett ing-Tertiary care paediatric centre and district general hospitals in the UK. Patients-Children attending the above centre for treatment of hypertension. The control subjects were normotensive healthy children attending district general hospitals for minor medical and surgical di sorders. Interventions-None, Main outcome measures-Plasma (P) and urin ary (U) NOx concentrations, blood pressure, and glomerular filtration rate. Results-Sixteen normal children (mean age 6.9 years), 13 childre n with renovascular hypertension (mean age 7.8 years), and 25 children with hypertension associated with renal parenchymal disease (mean age 10.7 years) were studied. Mean (SD) P-NOx values of children with hyp ertension with renovascular disease (15.3 (11.4) mu mol/l) and renal p arenchymal disease (18.3 (11.4) mu mol/l) were significantly above tha t of normal children (11.9 (5.9) mu mol/l) after accounting for age an d glomerular filtration rate influences. Higher concentrations of P-NO x in normal children were associated with younger age, but not in the children with hypertension. Higher P-NOx concentrations were also asso ciated with a lower glomerular filtration rate in normal children and children with hypertension with renal parenchymal disease, but not in the children with hypertension with renovascular disease. U-NOx excret ion expressed as a ratio against urine creatinine (U-creat) excretion was not statistically different among the study groups. Conclusions-P- NOx is increased in children with hypertension even after statistical elimination of the glomerular filtration rate and age influences. This suggests a normal or increased NO synthase activity in childhood hype rtension in contrast with adults with hypertension in whom it is descr ibed as reduced.