Assessment of In Vitro Airway Smooth Muscle Relaxant Activity of Rhus coriaria L. Fruit Ethanolic Extract and Its Possible Mechanisms

Rhus coriaria L. (Anacardiaceae), also known as Sumac, is commonly used as a spice, flavoring agent, and as a traditional medicinal herb. This includes also the traditional use for treating asthma, catarrh, and common colds. The accumulating evidence supports its cardioprotective, antidiabetic, neuroprotective, anticancer, gastroprotective, antibacterial, anti-inflammatory, antiviral, antioxidant, and respiratory effects. However, there are no previous studies that have shown its effects and mechanism in the airway smooth muscle tone, and therefore, the aim of our study was to investigate the in vitro pharmacological action of R. coriaria L. extract (RCE) on the rat isolated tracheal and bronchial preparations by exploring its relaxant activity and mechanism of action. The direct relaxant effect of RCE (0.1-0.7 mg/mL) was tested in the rat bronchi and trachea rings precontracted by carbachol (CCh). In addition, the pretreatment with RCE (1 mg/mL) was tested on the bronchial and tracheal reactivity induced by CCh, potassium chloride (KCl), or CaCl2. In addition, the cyclooxygenase inhibitor indomethacin and the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME), respectively, were used for exploring the mechanisms of RCE-induced relaxation and reduction of reactivity. Our findings demonstrated that RCE induced a concentration-dependent relaxation and a significant reduction of reactivity, significantly reduced with either indomethacin or L-NAME. In addition, RCE decreased the responsiveness to KCl and affected the extracellular Ca2+-induced contraction in the tissues with added CCh or KCl in Ca2+-free Krebs-Henseleit solution. In summary, we have shown that RCE displayed relaxant activities in the in vitro airway smooth muscles, and the possible mechanisms seems to involve the prostaglandin, nitric oxide, and Ca2+ pathways. Taken together, our findings indicate the potential role of RCE in the treatment of respiratory diseases with limited airflow, or obstructive respiratory diseases, and could justify its traditional use in the respiratory diseases.

Spirometric maneuvers and inhaled salbutamol do not affect exhaled nitric oxide measurements among patients with allergic asthma

BACKGROUND

Exhaled nitric oxide (ENO) is used as a marker of airway inflammation. Factors such as spirometric maneuvers (SPM), β(2)-agonists, or tobacco smoking have been postulated to affect ENO measurements. Guidelines on measurement techniques have been published based on expert opinions. Nevertheless, there is no strong clinical evidence of many aspects because they have not been supported by research data.

OBJECTIVES

The aim of this study was to evaluate the influence of performing a spirometry or receiving inhaled salbutamol on ENO readings.

METHODS

One hundred forty-five adults and 62 children with allergic asthma were included with a mean age of 36 ± 13 years for adults and 13 ± 2 years for children. A control group comprised 30 healthy adults and 30 children with a mean age of 37 ± 14 years and 13 ± 2 years, respectively. ENO measurements were performed with a NIOX-MINO® electrochemical device. In 179 patients ENO was measured before and after performing SPM and in 88 patients before and 15 min after SPM plus 2 puffs of salbutamol (100 μg/puff).

RESULTS

There were no significant differences in mean ENO levels before and after SPM or before and after SPM plus 2 puffs of inhaled salbutamol in adults or children (asthmatic or healthy).

CONCLUSIONS

Levels of ENO are not significantly affected by SPM or salbutamol inhalation.