Outlet about Sympathoadrenal Reactivity in Exercise-induced Asthma

At the time of the two exercise tests the relative humidity was 22 to 45 percent and the ambient temperature 22 to 24.5°C, as determined in 24 of the 48 experiments.

Pretrial Examination

Basal preexercise values for FEVi and VC were similar in the three groups, and all were within 75 percent of the predicted values. All patients with a history of EIA had decreases in FEVi of more than 15 percent following the pretrial exercise test, FEV10(per cent of control) whereas none in the NEIA group or the С group did (Fig 1A). In the EIA group there was no tendency toward recovery during the first 20 minutes after this maximal exercise test. Isoprenaline inhalation reestablished basal FEVi values in all individuals (Fig 1A). There was no significant difference between the basal preexercise FEVi and the value recorded after inhalation of Isoprenaline in any patient or control subject, indicating absence of bron-choconstriction in the basal state.

There was no significant difference between the three groups with regard to maximal V02 (Fig 2). Ve at the end of the exercise was greatest in the EIA group (118.9 ±: 13.2 L/min) and smallest in the NEIA group (104.2 dh 14.9 L/min). However, this difference was not statistically significant. There was no correlation between the degree of postexercise bronchoconstriction and the maximal Ve in the asthmatic patients (learn how to treat asthma).

Exercise

Trial Examination

The basal preexercise FEVi and VC did not differ from the basal values in the pretrial examination in any of the three groups (teia = 0.99, tneia = 0.93, rc = 0.99 for FEVi), indicating that the patients were also in a free interval at the time of the trial examination. No subject had a basal FEVi of less than 75 percent of the predicted value. Following the submaximal treadmill exercise test, FEVi decreased to less than 85 percent of preexercise values in six of the EIA patients but in none of the others. The postexercise recovery of the EIA patients was faster than after the pretrial testing, but was not complete within 25 minutes after exercise (Fig IB). All subjects completed the eight minute exercise test, with the exception of two patients in the EIA group who discontinued exercise after a shorter time than eight minutes (3’15 and 6′) due to dyspnea. Of  all patients in the EIA group, one of these patients had the highest noradrenaline level (27.02 nM), and the other patient had the highest adrenaline level (1.40 nM) immediately following exercise.  To see the results of other studies for Exercise-Induced Asthma, click on the link.

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There was no significant difference in basal preexercise Sgaw or FRC between the groups or between the two basal measurements in die same subject. Basal Raw at FRC exceeded 100 percent of the predicted value in three patients, all of whom belonged to the NEIA group, but did not exceed 125 percent of the predicted value in any patient. The postexercise Sgaw decreased to less than 65 percent of basal preexercise values in all EIA patients and in three of the NEIA patients, but in none of the control subjects (Fig 1C). Two patients in the NEIA group had a slight postexercise fall in FRC of less than 5 percent compared with basal preexercise values. All other subjects in this study had a postexercise increase in FRC (Fig 3).

One patient in each asthma group and two subjects in the C group could not complete the orthostatic test due to vasovagal reactions. Two of these individuals fainted. There were no statistically significant differences in mean arterial pressure at rest in the supine position or during standing when comparisons were made between the three groups. The mean increases in heart rate during standing were 10 to 20 beats/min in all three groups. The C group had slightly lower heart rates than the two patient groups. The basal plasma catecholamine levels were: noradrenaline, 1.36 ± 0.26 nM; adrenaline, 0.07 ±. 0.01 nM; and dopamine, 0.12 dr 0.04 nM in the С group. The basal catecholamine levels did not differ between the groups and there were no differences between the two resting samples. Noradrenaline and adrenaline levels were approximately doubled during the orthostatic test, while dopamine levels were unchanged (Fig 4). There was no difference between the groups with regard to plasma catecholamine reactivity in connection with the orthostatic test.

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The trial exercise test increased plasma noradrenaline by a factor of 11.9 (range 10.8 to 13.5) and plasma adrenaline by a factor of 10.2 (6.1 to 12.7), when calculated on all subjects participating in the study. Maximal catecholamine levels were obtained immediately after exercise. These were: noradrenaline, 14.72 ± 1.35 nM; and adrenaline, 0.83 =b 0.24 nM in the С group. There were no statistically significant differences between the groups with regard to maximal concentrations or maximal increases of noradrenaline and adrenaline obtained after exercise (Fig 4). There was no significant difference in dopamine levels at rest or following exercise. The increase in dopamine tended to be greatest in the NEIA group and smallest in the C group, in which the maximal concentration was 0.21 ± 0.05 nM. The difference, however, was not statistically significant. The catecholamine levels were normalized 25 minutes after exercise, as there was no significant difference compared with preexercise basal values. Heart rates during the last minute of the trial exercise test were 179 =t 6, 171 ± 3, and 172 it 3 beats/min in the EIA, NEIA, and С groups, respectively.

The basal preexercise plasma level of cAMP was 16.7 11 0.9 nM and of glycerol was 60 ± 5 /xM in the C group. There was no difference between the groups regarding these levels. Cyclic AMP levels were unchanged after the orthostatic test and were doubled following exercise (Fig 5). The glycerol concentrations rose slightly during standing and were about doubled to a maximal value five minutes after exercise. There was no significant difference between the groups with regard to plasma levels of cAMP and glycerol at rest or increases in connection with the orthostatic test or the exercise test.

When plasma levels of catecholamines, cAMP, and glycerol were correlated with V02 or Sgaw, no correlation was found, with the exception of a negative correlation between the postexercise increase in cAMP and decrease in Sgaw in the EIA group (r = 0.77). Thus, the more pronounced the postexercise bronchoconstriction, the less plasma cAMP increased following exercise (The Role of Beta Adrenergic Bronchodilators in the Treatment of Asthma – https://onlineasthmainhalers.com/beta-adrenergic-agonists-the-role-of-beta-adrenergic-bronchodilators-in-the-treatment-of-asthma-5.html). There was a positive correlation between the increase in plasma levels of cAMP and adrenaline in the С group (r = 0.81, p < 0.05) and in the whole population (r = 0.48, p < 0.05). Apart from this, no correlation was found between the exercise-induced changes in plasma levels of the substances analyzed.
Figure-1Figure 1. Percent change from basal level in: FEVj after pretrial maximal exercise test, including effect of Isoprenaline inhalation 20 min after exercise. Basal preexercise values (1): 4.28 ± 0.26 (C), 4.18 ± 0.38 (EIA), 4.08 ± 0.40 (NEIA). (B) FEV* after trial submaximal exercise test. Basal preexercise values (1): 4.27 ± 0.26 (C), 4.10 ± 0.37 (EIA), 4.29 ± 0.32 (NEIA). (C) Sgaw after the trial submaximal exercise test. Basal preexercise values (x s_1 x cm HoO1): 0.171 ± 0.019 (C), 0.136 ± 0.016 (EIA), 0.129 ± 0.013 (NEIA). Each point represents mean values from eight subjects (± SEM).

Figure-2Figure2. Maximal ventilation (Ve), maximal oxygen uptake (Vo2), and maximal heart rate in pretrial maximal exercise test. Mean values (±SEM) from eight subjects in each group.

Figure-3Figure3. Percent change in functional residual capacity (FRC)after submaximal exercise test. Each point represents mean values (± SEM) from eight subjects.

Figure-4Figure 4. Venous plasma levels of the catecholamines, noradrenaline, adrenaline, and dopamine. Mean values ( ± SEM) from eight subjects in each group. No significant differences were found between groups in catecholamine levels as evaluated by three-way analysis of variance.

Figure-5Figure 5. Plasma levels of cAMP and glycerol; no significant differences between groups. Mean values ( ± SEM) from eight subjects in each group.

Figure-6Figure6. Relationship between increases in plasma cyclic AMP during exercise test and postexercise decreases in airways conductance (Sgaw) in the EIA group (n=8).