Airway Responsiveness to Beta‐Adrenergic Agonist (Salbutamol) in Asthma

Abstract

Despite the controversy of airway responsiveness to beta2-agonist drugs in asthma, in a previous study we showed increased responsiveness of asthmatic airways to isoprenaline. Therefore, in the present study of airway sensitivity to other beta2-agonists, salbutamol and its relationship to histamine responsiveness was reexamined. The threshold bronchodilator concentrations of inhaled salbutamol required for a 20% increase in forced expiratory flow in 1 sec (FEV1), (PC20) was measured in 20 normal and 19 asthmatic adults. Airway responsiveness to histamine, as the concentration that caused a 20% decrease in FEV1, was also measured in 11 normal and 12 asthmatic subjects; and the correlation between PC20 salbutamol and PC20 histamine was evaluated. Sensitivity to salbutamol was greater in asthmatics (PC20 = 7.24 mg/L) than in non-asthmatics (PC20 = 124.25 mg/L, p< 0.001). Airway responsiveness to histamine in asthmatics (PC20 = 0.18 g/L) was also significantly greater than in normal subjects (PC20 = 19.46 g/L, p < 0.001). There was a significant correlation between PC20 salbutamol and histamine (Rs = 0.6052, p < 0.005). Maximum response to both salbutamol and histamine and slope of concentration-response curves of both agents were significantly greater in patients with asthma than in normal subjects (p < 0.001 and p < 0.005 for maximum response and slope, respectively). The increased sensitivity of asthmatics to inhaled salbutamol suggests that they also may be more sensitive to their endogenous adrenaline, which may thus dilate and stabilize their airways.

The effect of Nigella sativa alone, and in combination with dexamethasone, on tracheal muscle responsiveness and lung inflammation in sulfur mustard exposed guinea pigs

“…Sixteen to twenty years after exposure, main respiratory complications were diagnosed as COPD (35%), bronchiectasis (32.5%), asthma (25%), large airway narrowing (15%), pulmonary fibrosis (7.5%), and simple chronic bronchitis (5%) (Hefazi et al, 2005). The concentration-response curves to salbutamol in chemical war victims of our previous study (Boskabady et al, 2008a) compared to normal subjects were different from those of smokers (Boskabady and Farhadi, 2005) but were similar to the asthmatic patients with similar FEV 1 level (Boskabady and Saadatinejad, 2003). There is no exact treatment for respiratory disorders induced by SM exposure.…”

Airway Hyperresponsiveness to Methacholine in Chemical Warfare Victims

“…Eosinophils in BAL may demonstrate the importance of asthma as one of the main pulmonary complications of chemical warfare [7]. The cause of reversibility in airway obstruction may be due to development of sulfur mustard gas-induced AHR, as AHR to brochodilators (isoprenaline and salbutamol) in asthmatic patients and its relationship to responsiveness to bronchoconstrictors (methacholine and histamine) were demonstrated previously [23, 24]. …”

“…The maximum response to methacholine and histamine was significantly greater in asthmatic than in normal subjects [24, 33]. In most control subjects, a plateau in concentration-response curves to methacholine and histamine was achieved; while in asthmatic patients, a plateau in the curves was not obtained, which is a characteristic feature of concentration response of asthmatic patients [34].…”

Feasibility of Percutaneous Vagus Nerve Stimulation for the Treatment of Acute Asthma Exacerbations

“…[39][40][41][42] In animal studies, propranolol has been shown to inhibit the benefit of VNS in reducing bronchoconstriction. 20 Asthma patients have also been reported to be more sensitive to endogenous epinephrine, 43 and at physiologic concentrations treatment with an epinephrine infusion can induce bronchodilation in a dose-dependent manner and at a dose below that which affects blood pressure and heart rates. 44,45 Furthermore, b-adrenoceptors have a higher affinity for epinephrine (K d = 0.8 lmol ⁄ L) than for the sympathetic neurotransmitter norepinephrine (K d = 10 lmol ⁄ L).…”