We wanted to study the effects of a 600 micrograms inhaled salbutamol dose on the cardiovascular and respiratory autonomic nervous regulation in eight children suffering from bronchial asthma.
In this randomized, double-blind, placebo-controlled, crossover study we continuously measured electrocardiogram, finger systolic arterial pressure (SAP) and flow-volume spirometry at baseline as well as 20 min and 2 h after the drug inhalation. The R-R interval (the time between successive heart beats) and SAP variabilities were assessed by using spectral analysis. Baroreflex sensitivity was assessed by using cross-spectral analysis.
Salbutamol significantly decreased the total and low frequency (LF) variability of R-R intervals as well as the high frequency (HF) variability of R-R intervals and of SAP. Salbutamol significantly increased the LF/HF ratio of R-R intervals and of SAP, minute ventilation, heart rate and forced pulmonary function in comparison with placebo. The weight of the subjects significantly correlated positively with baroreflex sensitivity and negatively with heart rate after the salbutamol inhalation.
We conclude that the acute salbutamol inhalation decreases cardiovagal nervous responsiveness, increases sympathetic dominance in the cardiovascular autonomic balance, and has a tendency to decrease baroreflex sensitivity in addition to improved pulmonary function.
Spontaneously hypertensive rats (SHR) are generally considered as genetic model both for essential hypertension and attention-deficit hyperactivity syndrome. Neuroanatomical substrates and mechanisms of neural disorders in the SHR have not been elucidated. This study aimed to determine if the background impulse activity of Nucleus accumbens, core (NAc) neurons and their reactions evoked by amigdala stimulation in the SHR differ from those of normotensive Wistar rats (WR). Besides that we investigated the influence of microiontophoretic beta-adrenergic receptors agonist isoproterenol administration (5 mM solution; pH 5.0; 10-30 nA) on the NAc neuronal activity. Single unit extracellular recordings were performed under urethane anesthesia. These results showed that percentage of the NAc neurons with bursting discharge pattern of the background impulse activity is significantly (P
The effects of whole-body exposure to ambient temperatures of -15 degrees C and 23 degrees C on selected performance-related physiological variables were investigated in elite nonasthmatic cross-country skiers. At an ambient temperature of -15 degrees C we also studied the effects of the selective beta2-adrenergic agonist Salbutamol (0.4 mg x 3) which was administered 10 min before the exercise test. Eight male cross-country skiers with known maximal oxygen uptakes (VO2max) of more than 70 ml x kg(-1) x min(-1) participated in the study. Oxygen uptake (VO2), heart rate (fc), blood lactate concentration ([La-]b) and time to exhaustion were measured during controlled submaximal and maximal running on a treadmill in a climatic chamber. Lung function measured as forced expiratory volume in 1 s (FEV1) was recorded immediately before the warm-up period and at the conclusion of the exercise protocol. Submaximal VO2 and [La-]b at the two highest submaximal exercise intensities were significantly higher at -15 degrees C than at 23 degrees C. Time to exhaustion was significantly shorter in the cold environment. However, no differences in VO2max or fc were observed. Our results would suggest that exercise stress is higher at submaximal exercise intensities in a cold environment and support the contention that aerobic capacity is not altered by cold exposure. Furthermore, we found that after Salbutamol inhalation FEV1 was significantly higher than after placebo administration. However, the inhaled beta2-agonist Salbutamol did not influence submaximal and maximal VO2, fc, [La-]b or time to exhaustion in the elite, nonasthmatic cross-country skiers we studied. Thus, these results did not demonstrate any ergogenic effect of the beta2-agonist used.
The use of inhaled beta2-agonists is restricted in sports. No benefit of inhaled formoterol upon performance was found in healthy athletes under normal climatic conditions, but it has not been investigated whether formoterol improves performance in athletes during exposure to cold. To investigate the effect of inhaled formoterol vs placebo upon performance and lung function at -20 degrees C in 20 healthy male athletes. We used a randomized double-blind, placebo-controlled, cross-over design. The subjects performed a run until exhaustion after inhaled study drug. The speed was 95% of the predetermined maximal oxygen uptake (VO2 max) the first minute and increased to 107% of VO2 max for the remaining part of the test. Time until exhaustion, ventilation (VE), VO2, respiratory rate (RR), tidal volume (VT), heart rate (HR) and arterial oxyhemoglobin saturation (SPO2) were recorded during exercise. Lung function was measured before inhaling, after inhaling the study drug and after the treadmill run. Inhaled formoterol did not improve endurance performance in cold environments compared with placebo, although formoterol significantly improved lung function (FEV1, FEF50 and PEF) and HR 4 min after the start of the exercise. Inhaled formoterol did not improve endurance performance in healthy, well-trained athletes exposed to cold.
The mechanism by which 2(3H)-benzothiazolone, 4-hydroxy-7-[2-[[2-[[3-(2-phenylethoxy)propyl]-sulphonyl]ethyl]amino]ethyl]-monohydrochloride (AR-C68397AA; viozan), a dual dopamine D2/beta2-adrenoceptor agonist which has shown promise in the treatment of chronic obstructive pulmonary disease (COPD), inhibits the extravasation of plasma protein induced by capsaicin in the tracheas of Brown Norway rats has been re-evaluated. Viozan (10-30 microg/kg given intratracheally; i.t.) inhibited dose-dependently the extravasation of plasma protein tagged with Evans Blue into rat trachea induced by capsaicin (10 microg/kg i.t.). Similar effects were seen with the selective beta2-adrenoceptor agonist, salbutamol (3-10 microg/kg i.t.), but the selective dopamine D2 receptor agonist, quinagolide (10-30 microg/kg i.t.), was inactive. The effects of viozan and salbutamol were abolished by propranolol (3 mg/kg) given intraperitoneally (i.p.) but unaffected by sulpiride (3 mg/kg i.p.). Thus, in c,ontrast to claims in the literature, a functional response to dopamine D2 receptor activation in a preclinical model of oedema arising from sensory nerve fibre activation in the rat lung could not be demonstrated. Moreover, no qualitative difference could be demonstrated between the response to a dual D2/beta2-adrenoceptor agonist and a selective beta2-adrenoceptor agonist. The observations call into question whether a dual D2/beta2-adrenoceptor agonist such as viozan would bring added benefit over established selective beta2-adrenoceptor agonists in the therapy
In the experiments with white rats injected with atropin the condition of three types of physiological adrenergic reactions was studied (intravenous infusion of isopropylnoradrenaline at a rate of 2.0 micrograms/kg/min): chronotropic reaction of the heart, calorigenic and thermogenic reactions. Experimental hyperthyroidism was caused by subcutaneous injections of thriiodothyronine at a dose of 100 micrograms/kg a day. The results of experiments showed that the changes on the side of chronotropic, calorigenic and thermogenic reactions of catecholamine (isopropylnoradrenaline) are defined by two parabolic functions-one following another with the minimum point (crossing) in the region of 6-7 injections of the hormone. A conclusion is made that the condition of adrenergic physiological reactions during experimental hyperthyroidism at its different stages are different and have a complex character.