Increased plasma and salivary nitrite and decreased bronchial contribution to exhaled NO in pulmonary arterial hypertension

• Background Conflicting results on exhaled NO in pulmonary hypertension (PH) exist. Therefore, we analysedexhaled NO, as well as systemic and local nitrite, a possible alternative source of NO, in PH with regard to PHaetiology.Methods Exhaled NO at multiple flow-rates, as well as plasma and salivary nitrite and nitrate, was measured in22 patients with PH and 21 healthy controls. Alveolar NO (CalvNO) and bronchial flux (J’awNO) were calculatedusing the slope–intercept model. Patients with PH were subdivided into pulmonary arterial hypertension (PAH)and PH WHO Groups II–IV, according to the WHO clinical classification of PH.Results Exhaled NO was reduced at flow-rates in the range of 20)200 mL s)1 in patients with PAH (n = 13) vs.PH WHO Group II–IV (n = 9) (P < 0Æ05 all). Patients with PAH had higher CalvNO than healthy controls [2Æ61(2Æ23, 3Æ36) vs. 1.97 ppb (1Æ22, 2Æ49), P = 0Æ03] and similar to PH WHO Group II–IV (P = 0Æ51). Patients with PAHhad lower J’awNO than patients with PH WHO Group II–IV or healthy controls [430 (371, 702) vs. 807 (557, 993)or 731 pL s)1 (580, 818), P < 0Æ05 both]. Subjects with PAH were characterized by higher levels of salivary andplasma nitrite than healthy controls (P < 0Æ05 both).Conclusions Patients with PAH have lower bronchial NO flux compared to healthy controls and patients withPH WHO Group II–IV along with elevated salivary and plasma nitrite compared to controls. This implies reducedbronchial NO synthase-derived NO formation in PAH. Increased alveolar NO levels were found in subjects withPH compared to controls, especially in subjects with PAH. This may reflect NO diffusion disturbances in thealveoli.

Keyword

Exhaled nitric oxide

nitrate

nitrite

NO flow-independent exchange parameters

pulmonary hypertension

MEDICINE

MEDICIN

Publication and Content Type

ref (subject category)

art (subject category)