Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
3035247 | Autonomic Neuroscience | 2009 | 10 Pages |
Abstract
The interaction of purinergic and nitrergic mechanisms was evaluated in the caudal nucleus tractus solitarii (cNTS) using awake animals and brainstem slices. In awake animals, ATP (1.25 nmol/50 nL) was microinjected into the cNTS before and after the microinjection of a selective neuronal nitric oxide synthase (nNOS) inhibitor N-propyl-l-arginine (NPLA, 3 pmoles/50 nL, n = 8) or vehicle (saline, n = 4), and cardiovascular and ventilatory parameters were recorded. In brainstem slices from a distinct group of rats, the effects of ATP on the NO concentration in the cNTS using the fluorescent dye DAF-2 DA were evaluated. For this purpose brainstem slices (150 µm) containing the cNTS were pre-incubated with ATP (500 µM; n = 8) before and during DAF-2 DA loading. Microinjection of ATP into the cNTS increases the arterial pressure (AP), respiratory frequency (fR) and minute ventilation (VE), which were significantly reduced by pretreatment with N-PLA, a selective nNOS inhibitor (AP: 39 ± 3 vs 16 ± 14 mm Hg; fR: 75 ± 14 vs 4 ± 3 cpm; VE: 909 ± 159 vs 77 ± 39 mL kgâ 1 mâ 1). The effects of ATP in the cNTS were not affected by microinjection of saline. ATP significantly increased the NO fluorescence in the cNTS (62 ± 7 vs 101 ± 10 AU). The data show that in the cNTS: a) the NO production is increased by ATP; b) NO formation by nNOS is involved in the cardiovascular and ventilatory responses to microinjection of ATP. Taken together, these data suggest an interaction of purinergic and nitrergic mechanisms in the cNTS.
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Authors
Ãrica M. Granjeiro, Gisela P. Pajolla, Daniela Accorsi-Mendonça, Benedito H. Machado,