THE ROLE OF NITRIC OXIDE (NO) IN ALLERGIC AND CARRAGEENAN-INDUCED PLEURISY IN SPONTANEOUSLY HYPERTENSIVE RATS (SHR)

KWASNIEWSKI F. H.(1), FERREIRA A. A.(2), DELANI T. C. O.(2), CUMAN R. K. N.(2), CAPARROZ-ASSEF S. M.(2), JANCAR S.(3), BERSANI-AMADO C. A.(2)

(1)Integrated Nucleus of Biotechnology, University of Mogi das Cruzes-SP; (2)Lab. of Inflammation, University of Maringá, PR; (3)Dept. of Immunology, ICB/USP, SP, Brazil.

SHR differs from Wistar normotensive (NT) regarding allergic inflammation, and abnormalities in NO production/effect has been shown in SHR. Here we compared both strains response to allergic and carrageenan-induced pleurisy and the contribution of NO. Pleurisy was induced in male rats (250-300g) by carrageenan (CA, 200µg) or anaphylaxis (ANA, 1mg ovalbumin into sensitized rats - 10µg of ovalbumin in 10mg of Al(OH)3). Pleural exudates were collected 30min and 4h and measured as indicative of increased vascular permeability (iVP, as mL). To determine the total (performed in Turk) and differential (Giemsa stained) cell counts (as x103 cells/mm3), the cavity was washed with 2 mL of PBS. The inhibitor of NO synthesis (L-NAME 30mg/kg) was injected iv 30min before pleurisy. In ANA pleurisy iVP after 30 min was lower in SHR compared to NT (0.6±0.02 vs 0.9±0.05, respectively). This difference was no longer observed after 4h. At this time, the cell infiltration was not significantly different between strains (43±2.0 in SHR and 30±2 in NT). In both strains, PMN leukocytes accounted for more than 85% of the exudate cells. Pre-treatment with L-NAME did not modify these responses. The pleurisy to CA was observed only in the 4thh after its injection, and in this case iVP in SHR (0.7±0.03) were similar to NT (0.8±0.03) as well as the number of cells (61±3.1 in SHR and 64±2 in NT). L-NAME inhibited iVP by 55% in both strains and cell influx by 50% in SHR and 35% in NT. Inflammation in SHR differs from NT as a function of the nature of the stimulus. Endogenous NO contributes to CA-induced pleurisy but not to ANA.

KEY WORDS: pleurisy, anaphylaxis, carrageenan, nitric oxide, inflammation, hypertension.

FINANCIAL SUPPORT: CNPq; FAEP (Fundação de Amparo ao Ensino e Pesquisa), UMC.

CORRESPONDENCE TO:

Fábio Henrique Kwasniewski, Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes, Av. Dr. Cândido Xavier de Almeida Souza 200, Centro Cívico, CEP 08780-911 - Mogi das Cruzes, SP. Email: fhkwas@umc.br