p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor.
The aim of our study was to evaluate the effect of the iv administration of two different beta 2- receptors agonists, salbutamol and broxaterol, on the growth hormone (GH) response to maximal exercise in 11 patients (8 males and 3 females; age range 18-65 yr; mean +/- SE age 56 +/- 13 yr; BMI 26.2 +/- 1.4 kg/m2) with chronic asthmatic bronchitis. All the subjects underwent four cycloergometric exercise tests (incremental workload until maximal predicted heart rate). At baseline, at maximal exercise, at the end of the recovery period and 60 min after the end of each exercise, blood samples were drawn for the assay of GH, glucose, insulin, lactates, norepinephrine and epinephrine. Two exercises were performed without treatment while the remaining two were performed 60 min after the administration of 400 micrograms of either salbutamol or broxaterol (both diluted in 10 ml of saline) according to a randomized double blind cross-over design. Both exercise tests performed without treatment caused a significant (p < 0.05) and similar GH peak with respect to baseline values (from 0.3 +/- 0.1 micrograms/L to 2.8 +/- 1.3 micrograms/L, mean of the two exercise tests). Salbutamol pretreatment blunted the GH response to exercise which caused a no more significant serum GH peak over the baseline levels (from 0.6 +/- 0.2 micrograms/L to 1.4 +/- 0.6 micrograms/L,). Moreover, broxaterol completely abolished the GH response to exercise (baseline level 0.6 +/- 0.2 micrograms/L; peak levels 0.4 +/- 0.1 micrograms/L). The serum GH peak after exercise + broxaterol was significantly (p < 0.05) lower as compared to exercise + salbutamol. In conclusion, we have demonstrated for the first time that beta 2 stimulation blunts the physiological GH response to maximal exercise in adult human subjects. It can be suggested that changes in brain neurotransmitters, possibly an increase in the alpha-adrenergic tone, are likely to be involved in this endocrine effects of exercise.
Beclomethasone was effective in reducing airway hyperresponsiveness and in controlling symptoms of asthma, but it was associated with decreased linear growth. Salmeterol was not as effective as beclomethasone in reducing airway hyperresponsiveness or in controlling symptoms; however, it was an effective bronchodilator and was not associated with rebound airway hyperresponsiveness, masking of symptoms, or adverse effects.
Wheeze is a common symptom in infancy and is a common cause for both primary care consultations and hospital admission. Beta2-adrenoceptor agonists (b2-agonists) are the most frequently used as bronchodilator but their efficacy is questionable.
The standard curve was linear over the range 0.2-20 ng.mL-1. The intra- and interassay RSDs were 7.01% and 2.10% at 0.4 ng.mL-1, 2.18% and 5.25% at 4.0 ng.mL-1 and 4.61% and 4.85% at 15.0 ng.mL-1. The recoveries were between 90% and 110%. The pharmacokinetics of salbutamol aersol was described well with a two-compartment model, and the parameters for salbutamol inhaled and orally administered were assessed as follows: Tmax were (0.22 +/- 0.07) h and (1.8 +/- 0.6) h, Cmax were (3.4 +/- 1.1) ng.mL-1 and (3.9 +/- 1.4) ng.mL-1, T1/2 beta were (4.5 +/- 1.5) h and (4.6 +/- 1.1) h, respectively. The AUC0-20 min (inhal) was 7.94 times as high as the AUC0-20 min (p.o.). There were significant differences between Tmax, AUC, K12, K21, alpha and T1/2 alpha (P < 0.05). The relative bioavailability of salbutamol aerosol was 57.23% compared with its oral solution.
Asthma Control Test (ACT) is a simple tool for assessing the level of asthma control in clinical practice, and it has been validated in comparison with a general clinical assessment of asthma control, including forced expiratory volume in the first second (FEV(1)).
Data were used from 1465 patients with COPD entered into a large 1 year double blind trial with daily measurements of peak expiratory flow (PEF) and symptom scores.
The effects of various doses of salbutamol, d-amphetamine and d-fenfluramine were studied on sucrose intake by freely-fed rats. All the drugs reduced sucrose consumption dose-dependently. Bilateral electrolytic lesions in the ventral noradrenergic bundle, which deplete hypothalamic noradrenaline, antagonized the effect of 1.25 mg/kg d-amphetamine on sucrose intake. A dose of 2.5 mg/kg d, 1-propranolol, a beta adrenergic blocker, prevented the effect of 10 mg/kg salbutamol but the dose of 5 mg/kg did not significantly change the effect of 0.6 or 1.25 mg/kg d-amphetamine. Captopril (35 mg/kg) reduced salbutamol's effect on water intake, but not on sucrose intake. Metergoline, 1 mg/kg, a central serotonin antagonist, but not xylamidine 2 mg/kg, a 5HT antagonist with limited access to the brain, counteracted the effect of 2.5 mg/kg d-fenfluramine on sucrose intake. These findings suggest a role for serotoninergic and adrenergic mechanisms in inhibiting ingestive behaviour maintained mainly by taste.
Endothelin-expression is upregulated in bronchial epithelial cells of asthmatic patients with symptoms and evidence of functional derangement as compared with patients without symptoms and airflow obstruction. Exposure of cells from patients with asymptomatic asthma to factors that are released during acute exacerbation of the disease induces endothelin synthesis and release.