Bronchoconstriction and endogenous nitric oxide in isolated lungs of spontaneously hypertensive rats

Role of nitric oxide, bradykinin B2 receptor, and TRPV1 in the airway alterations caused by simvastatin in rats

Dry cough has been reported in patients receiving statin therapy. However, the underlying mechanism or other possible alterations in the airways induced by statins remain unknown. Thus, the aim of this study was to evaluate whether simvastatin promotes alterations in airways, such as bronchoconstriction and plasma extravasation, as well as the mechanism involved in these events. Using methods to detect alterations in airway resistance and plasma extravasation, we demonstrated that simvastatin [20 mg/kg, intravenous (i.v.)] caused plasma extravasation in the trachea (79.8 + 14.8 μg/g/tissue) and bronchi (73.3 + 8.8 μg/g/tissue) of rats, compared to the vehicle (34.2 + 3.6 μg/g/tissue and 29.3 + 5.3 μg/g/tissue, respectively). NG-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg, intraperitoneal), a nitric oxide (NO) synthase inhibitor, Icatibant [HOE 140, 10 nmol/50 μl, intratracheal (i.t.)], a bradykinin B2 antagonist, and capsazepine (100 nmol/50 μl, i.t.), a TRPV1 antagonist, attenuated simvastatin-induced plasma extravasation. Simvastatin (5, 10 and 20 mg/kg) did not cause bronchoconstriction per se, but exacerbated the bronchoconstrictive response to bradykinin (30 nmol/kg, i.v.), a B2 agonist (0.7 + 0.1 ml/H2O), or capsaicin (30 nmol/kg, i.v.), a TRPV1 agonist (0.8 + 0.1 ml/H2O), compared to the vehicle (0.1 + 0.04 ml/H2O and 0.04 + 0.01 ml/H2O, respectively). The bronchoconstriction elicited by bradykinin (100 nmol/kg, i.v.) in simvastatin non-treated rats was inhibited by L-NAME. The exacerbation of bronchoconstriction induced by bradykinin or capsaicin in simvastatin-treated rats was inhibited by L-NAME, HOE 140 or capsazepine. These results suggest that treatment with simvastatin promotes the release of bradykinin, which, via B2 receptors, releases NO that can then activate the TRPV1 to promote plasma extravasation and bronchoconstriction.

Arthritis induced by adjuvant in spontaneously hypertensive and normotensive rats: endogenous glucocorticoid effects on inflammatory response

The present study investigated arthritis induced by complete Freund adjuvant (AIA) in spontaneously hypertensive and normotensive rats (respectively, SHR and NTR rats). The inflammatory reaction was studied for 28 days by evaluating paw edema and secondary lesions found 10 days after complete Freund adjuvant (CFA) administration. The body weight of the animals and macroscopic alterations of several organs, including spleen, thymus, adrenal glands, and lymph nodes, were also analyzed. The results showed that the AIA manifestations were decreased in SHRs compared with NTRs. Moreover, this altered inflammatory response was not modified by surgical adrenalectomy.

Acute immune and non-immune inflammatory response in spontaneously hypertensive rats and normotensive rats. Role of endogenous nitric oxide

The present study investigated the acute inflammatory response (increase in vascular permeability and leukocytes migration) in the pleura of spontaneously hypertensive rats (SHR) and normotensive rats (NTR), using two different stimulus: carrageenan and active anaphylaxis. In addition, the role of endogenous nitric oxide in these responses was investigated.

RESULTS

The inflammatory response induced by intrapleural carrageenan injection in SHR developed similarly to that in NTR. Treatment with L-NAME, reduced the intensity of this response in both groups of rats. The inflammatory response induced by active anaphylaxis in SHR and NTR was different. The increase in vascular permeability occurred later in the SHR compared to NTR. The number of leukocyte present in inflammatory exudates was increased at 4 h in both groups of rats. L-NAME treatment did not inhibit exudation at the intervals under analysis, however, reduced the number of mononuclear cells in the inflammatory exudate of SHR.

CONCLUSION

The development of the inflammatory response in SHR differs from that in NTR, depending on the nature of the inflammatory stimulus. Endogenous NO plays a clear role in carrageenan-induced inflamma-tion, but not in immunologically mediated inflammation in the analyzed period.