Relaxing effect of a new ruthenium complex nitric oxide donor on airway smooth muscle of an experimental model of asthma in rats.

NO is a potent bronchodilator and NO-donor compounds have demonstrated clinical significance for obstructive airway diseases. This study evaluated the relaxation mechanisms of two NO donors, a ruthenium compound (TERPY), and sodium nitroprusside (SNP), in rat tracheas with ovalbumin-induced asthma (OVA group) and in another control group. The effect of TERPY and SNP was evaluated in tracheal rings in an isolated organ chamber. The contribution of K(+) channels, sGC/cGMP pathway, phosphodiesterases, and extra and intracellular Ca(2+) sources were analyzed. The TERPY and SNP-induced tracheal smooth muscle relaxation in both groups. However, the maximum effect induced by TERPY was higher than that of SNP in both control (110.2 ± 3.2% vs 68.3 ± 3.1%, P < 0.001) and OVA groups (106.1 ± 1.5% vs 49.9 ± 2.7%, P < 0.001). In the control group, TERPY relaxation was induced by the activation of K(+) channels and reduction of the calcium influx, while in the OVA group, these same effects were also brought about by TERPY, but with participation of the sGC/cGMP pathway. In both groups, SNP-induced relaxation occurred through the activation of K(+) channels, sGC/cGMP pathway and reduction of calcium influx. However, the activation of sGC pathway and reticular Ca(2+) -ATPase seemed to be reduced in the OVA group. Furthermore, TERPY is capable of reversing the contraction of carbachol in asthmatic bronchioles. Finally, TERPY and SNP relaxation mechanisms were modified by asthma. SNP presented less relaxation than TERPY, which induced full relaxation with greater participation of K(+) and Ca(2+) fluxes through the membrane, thereby making TERPY a promising drug for reversing the narrowing of airways.

Heterocyclic Compounds: Pharmacology of Pyrazole Analogs From Rational Structural Considerations.

Low quality of life and life-threatening conditions often demand pharmacological screening of lead compounds. A spectrum of pharmacological activities has been attributed to pyrazole analogs. The substitution, replacement, or removal of functional groups on a pyrazole ring appears consistent with diverse molecular interactions, efficacy, and potency of these analogs. This mini-review explores cytotoxic, cytoprotective, antinociceptive, anti-inflammatory, and antidepressant activities of some pyrazole analogs to advance structure-related pharmacological profiles and rational design of new analogs. Numerous interactions of these derivatives at their targets could impact future research considerations and prospects while offering opportunities for optimizing therapeutic activity with fewer adverse effects.

Vasorelaxant and Hypotensive Effects of Jaboticaba Fruit (Myrciaria cauliflora) Extract in Rats.

This study's aim was to determine the effect of hydroalcoholic extract of M. cauliflora (HEMC) on vascular tension and blood pressure in rats. In our in vitro studies using precontracted isolated aortas from rats, HEMC and acetylcholine (positive control) induced relaxation only in vessels with endothelium. Pretreatment with L-NAME (NO synthase inhibitor) or ODQ (soluble guanylyl cyclase (sGC) inhibitor) abolished the HEMC-induced relaxation. The treatment with MDL-12,330A (adenylyl cyclase (AC) inhibitor) or diclofenac (COX inhibitor) reduced HEMC-induced vasorelaxation. The blockade of muscarinic and ß-adrenergic receptors (by atropine and propranolol, resp.) did not promote changes in HEMC-induced vasorelaxation. In our in vivo studies, catheters were inserted into the right femoral vein and artery of anesthetized rats for HEMC infusion and the measurement of blood pressure, heart rate, and aortic blood flow. The intravenous infusion of HEMC produced hypotension and increased aortic blood flow with no changes in heart rate. These findings showed that HEMC induces endothelium-dependent vascular relaxation and hypotension with no alteration in heart rate. The NO/sGC/cGMP pathway seems to be the main cellular route involved in the vascular responsiveness.