New knowledge about the neural aspects of cough has revealed
a complex network of pathways that initiate cough. The effect of
inflammation on cough neural processing occurs at multiple
peripheral and central sites within the nervous system. Evidence
exists that direct or indirect neuroimmune interaction induces
a complex response, which can be altered by mediators released
by the sensory or parasympathetic neurons and vice versa. The
aim of this study was to clarify changes of cough reflex sensitivity
– the activity of airway afferent nerve endings - in asthmatic
children. 25 children with asthma and 15 controls were submitted
to cough reflex sensitivity measurement - capsaicin aerosol in
doubling concentrations (from 0.61 to 1250 µmol/l) was inhaled
by a single breath method. Concentrations of capsaicin causing
two (C2) and five coughs (C5) were reported. Asthmatic children'
(11 boys and 14 girls, mean age 9 ± 1 yrs) cough reflex sensitivity
(geometric mean, with the 95 % CI) for C2 was 4.25 (2.25-8.03)
µmol/l vs. control C2 (6 boys and 9 girls, mean age 8 ± 1 yrs) was
10.61 (5.28-21.32) µmol/l (p=0.024). Asthmatic children' C5 was
100.27 (49.30-203.93) µmol/l vs. control C5 56.53 (19.69-162.35)
µmol/l (p=0.348). There was a statistically significant decrease of
C2 (cough threshold) in the asthmatic patients relative to controls
(p-value for the two-sample t-test of log(C2) for the one-sided
alternative, p-value = 0.024). The 95 % confidence interval for the
difference of the mean C2 in asthma vs. control, [1.004, 6.207].
For C5, the difference was not statistically significant (p-value =
0.348). There was a statistically significant decrease of cough
reflex sensitivity (the activity of airway afferent nerve endings) -
C2 value in the asthmatic children relative to controls.
Laboratory research of cough reflex utilizes almost exclusively
male guinea pigs – a practice that represents a significant obstacle
in the successful translation of results into clinical practice. Chronic
hypersensitivity cough syndrome affects mostly postmenopausal
women and it represents significant decrease in patient’s quality
of life. No cause for such exaggerated cough can be found,
therefore this condition cannot be treated appropriately. One of
the reasons leading to the lack of relevant data about mechanisms
responsible for hypersensitivity of cough related pathways is
nowadays widely discussed gender bias, which is present in nearly
all branches of biomedical research. Since gender differences in
cough reflex physiology do exist in humans, it would be reasonable
to study cough-related phenomena on both sexes of laboratory
animals. In this study, we focused on detailed characterization of
cough response of female guinea pigs to aerosols of commonly
used tussive agents (capsaicin, distilled water, allyl isothiocyanate,
cinnamaldehyde, citric acid). In pooled data from multiple
challenges we found no statistical difference in number of cough
and cough latency between sexes. Based on our results we
conclude that the utilization of female guinea pigs model does not
lead to messy data and can be used in basic cough research.
Respiratory sinus arrhythmia (RSA), i.e. heart rate (HR) variations
during inspiration and expiration, is considered as a noninvasive
index of cardiac vagal control. Mitral valve prolapse (MVP) could
be associated with increased cardiovascular risk; however, the
studies are rare particularly at adolescent age. Therefore, we
aimed to study cardiac vagal control indexed by RSA in adolescent
patients suffering from MVP using short-term heart rate variability
(HRV) analysis. We examined 12 adolescents (girls) with MVP (age
15.9±0.5 years) and 12 age and gender matched controls. Resting
ECG was continuously recorded during 5 minutes. Evaluated HRV
indices were RR interval (ms), rMSSD (ms), pNN50 (%), log HF
(ms2
), peak HF (Hz) and respiratory rate (breaths/min). RR interval
was significantly shortened in MVP group compared to controls
(p=0.004). HRV parameters-rMSSD, pNN50 and log HF were
significantly lower in MVP compared to controls (p=0.017,
p=0.014, p= 0.015 respectively). Our study revealed reduced RSA
magnitude indicating impaired cardiac vagal control in MVP already
at adolescent age that could be crucial for early diagnosis of
cardiovascular risk in MVP.