Metachrony drives effective mucociliary transport via a calcium-dependent mechanism.

The mucociliary transport apparatus is critical for maintaining lung health via the coordinated movement of cilia to clear mucus and particulates. A metachronal wave propagates across the epithelium when cilia on adjacent multiciliated cells beat slightly out of phase along the proximal-distal axis of the airways in alignment with anatomically directed mucociliary clearance. We hypothesized that metachrony optimizes mucociliary transport (MCT) and that disruptions of calcium signaling would abolish metachrony and decrease MCT. We imaged bronchi from human explants and ferret tracheae using micro-optical coherence tomography (µOCT) to evaluate airway surface liquid depth (ASL), periciliary liquid depth (PCL), cilia beat frequency (CBF), MCT, and metachrony in situ. We developed statistical models that included covariates of MCT. Ferret tracheae were treated with BAPTA-AM (chelator of intracellular Ca2+), lanthanum chloride (nonpermeable Ca2+ channel competitive antagonist), and repaglinide (inhibitor of calaxin) to test calcium dependence of metachrony. We demonstrated that metachrony contributes to mucociliary transport of human and ferret airways. MCT was augmented in regions of metachrony compared with nonmetachronous regions by 48.1%, P = 0.0009 or 47.5%, P < 0.0020 in humans and ferrets, respectively. PCL and metachrony were independent contributors to MCT rate in humans; ASL, CBF, and metachrony contribute to ferret MCT rates. Metachrony can be disrupted by interference with calcium signaling including intracellular, mechanosensitive channels, and calaxin. Our results support that the presence of metachrony augments MCT in a calcium-dependent mechanism.NEW & NOTEWORTHY We developed a novel imaging-based analysis to detect coordination of ciliary motion and optimal coordination, a process called metachrony. We found that metachrony is key to the optimization of ciliary-mediated mucus transport in both ferret and human tracheal tissue. This process appears to be regulated through calcium-dependent mechanisms. This study demonstrates the capacity to measure a key feature of ciliary coordination that may be important in genetic and acquired disorders of ciliary function.

Effects of Thickening Agents on the Mucociliary Transport Function: Comparison by the Type of Thickening Agents and the Viscosity of Thickened Water.

Thickening agents effectively prevent liquid aspiration, but their impact on the ease of discharging aspirated liquids from the trachea remains unclear due to alterations in the physical properties of liquids. This study clarifies the effects of thickening agents, comprising various raw materials, on mucociliary transport function, focusing on the viscosities of thickened waters. The subjects were 23 healthy adults. Five types of saccharin solution were prepared: a solution without a thickening agent, a starch-based nectar-like solution, a starch-based honey-like solution, a xanthan-gum-based nectar-like solution, and a xanthan-gum-based honey-like solution. Using these five types of saccharin solutions randomly, each subject underwent five trials of the saccharine dye test to evaluate the mucociliary transport function of the respiratory tract. The saccharin time was defined as the time from the placement of the saccharin solution on the nasal vestibule of the subject to when the subject reported that they became aware of the sweetness. The saccharin transit times for all samples of thickened water were longer compared to those of water without a thickening agent (p < 0.01). A comparison between thickened water samples with different viscosities showed that the saccharin transit time was longer when thickened water samples with high viscosity were prepared using the same thickening agent (p < 0.01). This suggests that while thickening reduces aspiration, the use of thickening agents may increase the difficulty in discharging aspirated fluids from the trachea.

Postnasal Drip.

Postnasal drip (PND) is a common symptom encountered when evaluating subjects with sinonasal disease; it may be present without sinonasal disease or as a symptom of laryngopharyngeal reflux. It is postulated that PND stems from dysfunction of normal mucus clearance mechanisms; however, there is no definitive evidence elucidating an exact pathophysiology. Compounding the uncertainties surrounding PND is the lack of an objective assessment tool. Instead, treating physicians must rely on subjective complaints and investigators utilize validated patient-reported outcome instruments, such as the Sino-Nasal Outcome Test, to determine treatment efficacy. This review seeks to discuss the current understanding of PND and evidence regarding effective treatment strategies.

Nasal polyps show decreased mucociliary transport despite vigorous ciliary beating.

OBJECTIVE: Mucociliary transport function in the airway mucosa is essential for maintaining a clean mucosal surface. This function is impaired in upper and lower airway diseases. Nasal polyps are a noticeable pathological feature that develop in some of the patients with chronic rhinosinusitis. Like ordinary nasal mucosae, nasal polyps have a ciliated pseudostratified epithelium with vigorous ciliary beating. We measured ex vivo Mucociliary Transport Velocity (MCTV) and Ciliary Beat Frequency (CBF) and explored the expressions of Planar Cell Polarity (PCP) proteins in nasal polyps in comparison with turbinate mucosae. METHODS: Inferior turbinates and nasal polyps were surgically collected from patients with chronic rhinosinusitis. Ex vivo MCTV and CBF were measured using a high-speed digital imaging system. Expressions of PCP proteins were explored by fluorescence immunohistochemistry and quantitative RT-PCR. RESULTS: The MCTV of nasal polyps was significantly lower than that of the turbinates (7.43 ±â€¯2.01 vs. 14.56 ±â€¯2.09 µm/s; p = 0.0361), whereas CBF did not differ between the two tissues. The MCTV vector was pointed to the posteroinferior direction in all turbinates with an average inclination angle of 41.0 degrees. Immunohistochemical expressions of Dishevelled-1, Dishevelled-3, Frizzled3, Frizzled6, Prickle2 and Vangl2 were lower in the nasal polyps than in the turbinates. Confocal laser scanning microscopy showed that Frizzled3 was localized along the cell junction on the apical surface. The expression levels of mRNAs for Dishevelled-1, Dishevelled-3 and Frizzled3 in the nasal polyps were also decreased in comparison with the turbinates. CONCLUSION: These results indicate that muco ciliary transport in nasal polyps is impaired although vigorous ciliary beating is maintained, and that the impairment may be caused by a decrease in Dishevelled/Frizzled proteins and resultant PCP disarrangement. LEVEL OF EVIDENCE: Level 3.

Nasal polyps show decreased mucociliary transport despite vigorous ciliary beating

Abstract Objective Mucociliary transport function in the airway mucosa is essential for maintaining a clean mucosal surface. This function is impaired in upper and lower airway diseases. Nasal polyps are a noticeable pathological feature that develop in some of the patients with chronic rhinosinusitis. Like ordinary nasal mucosae, nasal polyps have a ciliated pseudostratified epithelium with vigorous ciliary beating. We measured ex vivo Mucociliary Transport Velocity (MCTV) and Ciliary Beat Frequency (CBF) and explored the expressions of Planar Cell Polarity (PCP) proteins in nasal polyps in comparison with turbinate mucosae. Methods Inferior turbinates and nasal polyps were surgically collected from patients with chronic rhinosinusitis. Ex vivo MCTV and CBF were measured using a high-speed digital imaging system. Expressions of PCP proteins were explored by fluorescence immunohistochemistry and quantitative RT-PCR. Results The MCTV of nasal polyps was significantly lower than that of the turbinates (7.43 ± 2.01 vs. 14.56 ± 2.09 μm/s; p= 0.0361), whereas CBF did not differ between the two tissues. The MCTV vector was pointed to the posteroinferior direction in all turbinates with an average inclination angle of 41.0 degrees. Immunohistochemical expressions of Dishevelled-1, Dishevelled-3, Frizzled3, Frizzled6, Prickle2 and Vangl2 were lower in the nasal polyps than in the turbinates. Confocal laser scanning microscopy showed that Frizzled3 was localized along the cell junction on the apical surface. The expression levels of mRNAs for Dishevelled-1, Dishevelled-3 and Frizzled3 in the nasal polyps were also decreased in comparison with the turbinates. Conclusion These results indicate that muco ciliary transport in nasal polyps is impaired although vigorous ciliary beating is maintained, and that the impairment may be caused by a decrease in Dishevelled/Frizzled proteins and resultant PCP disarrangement. Level of evidence: Level 3.

Nasal mucociliary transportability of male and female smokers / Transportabilidade mucociliar nasal de homens e mulheres tabagistas

Abstract Introduction: Female smoker's present increased susceptibility to several diseases when compared to the opposite gender. However, there are no studies showing differences in nasal mucociliary transport behavior between male and female smokers. Objective: To compare the nasal mucociliary transportability in male and female smokers and non-smokers, taking into consideration age, anthropometric data, smoking load and pulmonary function. Methods: The analysis included 139 individuals (33 men and 37 women smokers and 32 men and 37 women non-smokers). All participants answered an initial interview to obtain personal data and smoking load. Anthropometric data and carbon monoxide in the exhaled air were assessed. Individuals also performed pulmonary function test and Saccharin Transit Time test. To compare saccharin transit time values between men and women, smokers and non-smokers, stratification of all independent variables was performed (sociodemographic, smoking and respiratory variables) into two categories: below and above the median values. Results: There was no difference between men and women, smokers and non-smokers, regarding nasal mucociliary transportability. Significant differences were only observed between non-smokers. Among those with less forced vital capacity values (<97.37% of predicted), women presented mucociliary transport faster than men. Moreover, it was observed influence of BMI and COex (women smokers), FCV and FEV1 (men non-smokers) and FEF25-75% (women non-smokers) on saccharin transit time values. Conclusion: Based on the findings of this study, nasal mucociliary transport in male and female adult smokers, apparently healthy, are similar.

Resumo Introdução: Mulheres tabagistas apresentam maior susceptibilidade à diversas doenças quando comparadas ao sexo masculino. No entanto, não há estudos mostrando diferenças no comportamento do transporte mucociliar nasal entre tabagistas do sexo masculino e feminino. Objetivo: Comparar a transportabilidade mucociliar nasal em homens e mulheres fumantes e não fumantes, levando em consideração idade, dados antropométricos, carga tabágica e função pulmonar. Método: A análise incluiu 139 indivíduos (33 homens e 37 mulheres fumantes e 32 homens e 37 mulheres não fumantes). Todos os participantes responderam a uma entrevista inicial para a obtenção de dados pessoais e a carga tabágica. Dados antropométricos e monóxido de carbono no ar expirado foram avaliados. Os indivíduos também fizeram teste de função pulmonar e o teste de trânsito de sacarina. Para comparar os valores do teste de trânsito de sacarina entre homens e mulheres, fumantes e não fumantes, foi feita a estratificação de todas as variáveis independentes (variáveis sociodemográficas, tabágicas e respiratórias) em duas categorias: abaixo e acima dos valores médios. Resultados: Não houve diferenças entre homens e mulheres, fumantes e não fumantes, em relação à transportabilidade mucociliar nasal. Diferenças significativas foram observadas apenas entre não fumantes. Entre os que apresentaram valores menores de capacidade vital forçada (< 97,37% do previsto), as mulheres apresentaram transporte mucociliar mais rápido do que os homens. Além disso, observou-se influência do IMC e COex (mulheres fumantes), CVF e VEF1 (homens não fumantes) e FEF25%-75% (mulheres não fumantes) sobre os valores do teste de trânsito de sacarina. Conclusão: Com base nos achados deste estudo, o transporte mucociliar nasal em tabagistas masculinos e femininos adultos, aparentemente saudáveis, são semelhantes.

Isotonic saline nasal irrigation in clinical practice: a literature review / O uso da ducha nasal com solução salina na prática clínica: uma revisão da literatura

Abstract Introduction: Nasal instillation of saline solution has been used as part of the treatment of patients with upper respiratory tract diseases. Despite its use for a number of years, factors such as the amount of saline solution to be used, degree of salinity, method and frequency of application have yet to be fully explained. Objective: Review the reported outcomes of saline nasal irrigation in adults with allergic rhinitis, acute or chronic sinusitis and after functional endoscopic sinus surgery (FESS), and provide evidence to assist physiotherapists in decision making in clinical practice. Methods: A search was conducted of the Pubmed and Cochrane Library databases between 2007 and 2014. A combination of the following descriptors was used as a search strategy: nasal irrigation, nasal lavage, rhinitis, sinusitis, saline, saline solution. Results: Eight clinical trials were included, analyzed according to participant diagnosis. Conclusion: The evidence found was heterogeneous, but contributed to elucidating uncertainties regarding the use of nasal lavage in the clinical practice of physical therapy, such as the protocols used.

Resumo Introdução: A instilação nasal de solução salina tem sido utilizada como parte do tratamento de pacientes com doenças do trato respiratório superior. Apesar de ser utilizada há vários anos, fatores como: quantidade da solução a ser instilada, grau de salinidade, modo e frequência de aplicação ainda não foram totalmente elucidados. Objetivo: Revisar os desfechos evidenciados no uso da irrigação nasal salina em adultos com rinite alérgica, sinusite aguda ou crônica e em pós-operatório de cirurgia endoscópica dos seios da face (CES) além de fornecer evidências para a tomada de decisões do fisioterapeuta na sua prática clínica. Métodos: Realizou--se uma busca nas bases de dados Pubmed e Cochrane Library no período compreendido entre 2007 e 2014. Foi utilizada como estratégia a combinação dos seguintes descritores: nasal irrigation, nasal lavage, rhinits, sinusitis, saline, saline solution. Resultados: Foram incluídos oito ensaios clínicos, analisados de acordo com o diagnóstico dos participantes. Conclusão: As evidências encontradas mostraram-se heterogêneas, mas contribuíram para elucidar alguns pontos obscuros na prática clínica da fisioterapia com relação ao uso da ducha nasal, como por exemplo, os protocolos utilizados.

Relações entre atividade física, tabagismo, transportabilidade mucociliar nasal e função pulmonar / Relationships between physical activity, smoking, nasal mucociliary transportability and pulmonary function

OBJETIVOS: Comparar indivíduos tabagistas e não tabagistas, ativos e insuficientemente ativos fisicamente, quanto à transportabilidade mucociliar nasal e à função pulmonar. MÉTODOS: Estudo de delineamento transversal. Os voluntários responderam a uma entrevista para obtenção de dados pessoais, informação sobre hábitos tabagísticos e nível de atividade física. Após, eles foram avaliados quanto aos dados antropométricos, transporte mucociliar nasal (pelo teste do tempo de trânsito da sacarina) e função pulmonar (pela mensuração do volume expiratório forçado no primeiro segundo e da capacidade vital forçada). Foram utilizados a análise de variância para investigação entre os grupos e a análise de covariância (ajustada por fatores de confusão) para investigação de cofatores sobre o tempo de trânsito de sacarina. Foram adotados o nível de significância de 5% e o intervalo de confiança de 95%. RESULTADOS: Foram selecionados 139 indivíduos, alocados em quatro grupos, de acordo com o hábito tabagístico e o nível de atividade física: 45 tabagistas insuficientemente ativos fisicamente; 25 tabagistas ativos fisicamente; 31 não tabagistas insuficientemente ativos; e 38 não tabagistas ativos fisicamente. As médias de idade e os índices de massa corporal não apresentaram diferenças estatisticamente significativas entre os quatro grupos. No teste do tempo de trânsito da sacarina os indivíduos não fumantes fisicamente ativos apresentaram um tempo de 8,73 minutos, enquanto nos insuficientemente ativos o tempo foi de 13,0 minutos (p=0,0409). Os fumantes fisicamente ativos apresentaram menores valores de volume expiratório forçado no primeiro segundo em comparação aos insuficientemente ativos (escore z em relação aos valores preditos -1,01 e -0,55, respectivamente; p=0,0207). CONCLUSÕES: Nesta amostra de indivíduos adultos, sadios, de ambos os sexos, a prática de atividade física foi benéfica para a transportabilidade mucociliar nasal, porém somente nos indivíduos que nunca fumaram. Por outro lado, os tabagistas fisicamente ativos apresentaram menores valores de função pulmonar quando comparados aos tabagistas insuficientemente ativos, sugerindo que os exercícios ísicos possam provocar prejuízos adicionais à função pulmonar se o indivíduo não modificar o hábito de fumar.

AIMS: To compare smokers and non-smokers, physically active and insufficiently active, on mucociliary transportability and lung function. METHODS: Cross-sectional study. The volunteers were interviewed to obtain personal data, information on smoking habits and level of physical activity. Then, they were evaluated for anthropometric data, nasal mucociliary transport (by saccharin transit time test) and lung function (by measuring forced expiratory volume in the first second and forced vital capacity). Analysis of variance was used for investigation between the groups and analysis of covariance (adjusted for confounding factors) to investigate cofactors on the transit time of saccharin. The significance level of 5% and the 95% confidence interval were adopted. RESULTS: A total of 139 individuals were selected and assigned to four groups, according to the smoking habits and the level of physical activity: 45 smokers who were not physically active; 25 physically active smokers; 31 non-smokers who were not physically active; and 38 physically active non-smokers. The mean age and body mass index did not present statistically significant differences between the four roups. In the saccharin transit time test, physically active non-smokers presented a time of 8.73 minutes, while in the insufficiently active, the time was 13.0 minutes (p=0.0409). Physically active smokers presented lower values of forced expiratory volume in the first second compared to those who were not physically active (z score in relation to predicted values -1.01 and -0.55, respectively; p=0.0207). CONCLUSIONS: In this sample of healthy adults of both sexes, the practice of physical activity was beneficial for nasal mucociliary transportability, but only in individuals who never smoked. On the other hand, physically active smokers presented lower values of lung function when compared to insufficiently active smokers, suggesting that physical exercises may cause additional lung function impairment if the individual does not change the smoking habit.

Chemical composition modulates the adverse effects of particles on the mucociliary epithelium

OBJECTIVE:We compared the adverse effects of two types of real ambient particles; i.e., total suspended particles from an electrostatic precipitator of a steel mill and fine air particles from an urban ambient particulate matter of 2.5 µm, on mucociliary clearance.METHOD:Mucociliary function was quantified by mucociliary transport, ciliary beating frequency and the amount of acid and neutral mucous in epithelial cells through morphometry of frog palate preparations. The palates were immersed in one of the following solutions: total suspended particles (0.1 mg/mL), particulate matter 2.5 µm 0.1 mg/mL (PM0.1) or 3.0 mg/mL (PM3.0) and amphibian Ringer’s solution (control). Particle chemical compositions were determined by X-ray fluorescence and gas chromatography/mass spectrometry.RESULTS:Exposure to total suspended particles and PM3.0 decreased mucociliary transport. Ciliary beating frequency was diminished by total suspended particles at all times during exposure, while particulate matter of 2.5 µm did not elicit changes. Particulate matter of 2.5 µm reduced epithelial mucous and epithelium thickness, while total suspended particles behaved similarly to the control group. Total suspended particles exhibited a predominance of Fe and no organic compounds, while the particulate matter 2.5 µm contained predominant amounts of S, Fe, Si and, to a lesser extent, Cu, Ni, V, Zn and organic compounds.CONCLUSION:Our results showed that different compositions of particles induced different airway epithelial responses, emphasizing that knowledge of their individual characteristics may help to establish policies aimed at controlling air pollution.

Efeitos da desobstrução rinofaríngea retrógada isolada e associada à instilação de soro fisiológico (0,9NACL), sobre as propriedades do muco nasal, a celularidade e as citocinas em lavado nasal e sintomas nasais de motociclistas profissionais expostos à poluição da cidade de Belo Horizonte / Effects of isolated clearance rhinopharyngeal retrograde and clearance rhinopharyngeal retrograde associated with the irrigation of isotonic saline solution (0.9NaCl) on the nasal mucus properties, celularity, and in nasal lavage and the nasal symptoms in professional motorcyclists exposed to air pollutions in the city of Belo Horizonte, Brazil

Introdução: A desobstrução rinofaríngea retrógrada (DRR) é uma técnica de fisioterapia respiratória aplicada em lactentes para desobstrução de vias aéreas superiores, podendo, inclusive, ser associada à irrigação nasal com salina isotônica para remoção de muco viscoso aderido às paredes das vias aéreas. Objetivo: Caracterizar o perfil de motociclistas profissionais expostos à poluição urbana no que se refere a transporte mucociliar nasal (TMCN), inflamação das vias aéreas superiores e sintomas nasais, e comparar o efeito da DRR isolada e associada à instilação de salina isotônica (DRR+S) nesta população. Métodos: Vinte e quatro voluntários divididos aleatoriamente em dois grupos (DRR e DRR+S) submeteram-se a 15 dias consecutivos de tratamento. A avaliação basal e a pós-intervenção constituíram-se da análise do teste de trânsito da sacarina, da celularidade total e diferencial do lavado nasal e dos sintomas de vias aéreas superiores por meio do questionário SNOT-20, bem como do estudo da exposição pessoal à poluição do ar, por meio da análise da concentração do NO2 de amostradores passivos. O TMCN foi avaliado pelo teste ANOVA não paramétrico com medidas repetidas e o SNOT-20 pelo teste Mann-Whitney. As correlações entre a concentração de NO2 e os desfechos das vias aéreas superiores foram testadas por meio do coeficiente de correlação de Spearman. Resultados: Os grupos apresentaram dados clínicos e demográficos semelhantes. O TMCN apresentou-se alterado em 25% dos voluntários e 100% deles apresentavam sintomas de vias aéreas superiores. Após os tratamentos, os sintomas de vias aéreas e o TMCN evidenciaram melhora significativa, apesar do aumento no número de macrófagos e células ciliadas do lavado nasal. Não houve correlação entre o NO2 e o TMCN, tampouco em relação aos sintomas de vias aéreas superiores. CONCLUSÃO: Técnicas não farmacológicas, simples e de baixo custo são efetivas para recuperar o TMCN alterado e melhorar os sintomas de vias aéreas...

Introduction: Rhinopharyngeal Retrograde Clearance (RRC) is a respiratory therapy technique applied to infants with upper airway obstruction that may also be associated with nasal irrigation with isotonic saline for removal of viscous mucus adhered to the walls of the airways. OBJECTIVE: Characterize the profile of professional motorcycles exposed to urban pollution in relation to the nasal mucociliary transport (NMCT), inflammation of the upper airways and nasal symptoms and compare the effect of DRR alone and associated with instillation of isotonic saline (RCC + S). Methods: Twenty-four volunteers were randomly divided into two groups (RCC and RCC + S) and were submitted to 15 consecutive days of treatment. The baseline and post-intervention consisted of analysis of the transit saccharin test, the total and differential cellularity nasal lavage, and symptoms of upper airway through the SNOT-20, as well as the study of personal exposure to air pollution, by analyzing the concentration of diffuse nitrogen dioxide monitoring system. The NMCT was evaluated with ANOVA for repeated measures and the SNOT-20 with the Mann-Whitney test. The correlations between the concentration of NO2 and the upper airway outcomes were tested using the Spearman correlation coefficient. Results: The groups showed similar demographic and clinical data. The NMCT was abnormal in 25% of the volunteers and 100% of the volunteers had symptoms of upper airways. After treatment the upper airway symptoms and the NMCT showed significant improvement despite the increase in the number of macrophages and ciliated cells on the nasal lavage. No correlation was observed between dioxide nitrogen and TMCN and with the symptoms of the upper airways. Conclusion: Nonpharmacological, simple and inexpensive techniques are effective to treat abnormal NMCT and improve symptoms of upper airway in nonsmoking adults...

Métodos de estudo do transporte mucociliar: [revisão] / Methods for studying mucociliary transport: [review]

Disfunções no transporte mucociliar trazem desde queda na qualidade de vida dos pacientes, como nas rinites e rinossinusites crônicas, até graves conseqüências com risco de seqüelas irreversíveis e mesmo letais, como nos casos de fibrose cística e das discinesias ciliares primárias. Desta forma, torna-se fundamental o conhecimento do funcionamento normal do aparelho mucociliar e de como alterações em seus componentes (cílio, muco-fluido periciliar e interação dinâmica entre ambos) afetam o transporte das secreções respiratórias. OBJETIVOS: Este artigo visa a revisar e discutir as diferentes técnicas de avaliação do transporte mucociliar descrevendo suas peculiaridades e aplicabilidades clínicas e experimentais. CONCLUSÕES: Os métodos citados nesta revisão nos fornecem informações importantes sobre os diferentes aspectos do transporte mucociliar. Alguns apresentam uma maior facilidade de realização e resultados reprodutíveis, já outros apenas mostraram-se com aplicabilidade em protocolos de pesquisa em virtude de dificuldades técnicas e limitações financeiras. Há que se considerar a inexistência de métodos que avaliem ambulatorialmente a freqüência de batimento ciliar (FBC) "in vivo" e "in situ", o que se tornaria uma ferramenta importante, tanto no âmbito científico, quanto na prática clínica, auxiliando no diagnóstico das discinesias ciliares e evitando a realização de procedimentos mais invasivos para a sua confirmação diagnóstica.

Mucociliary transport dysfunctions can impair the quality of life of patients suffering from chronic rhinossinusitis and lead to severe consequences such as alterations in respiratory physiology or even death as in cases of cystic fibrosis and primary ciliary dyskinesia. Therefore, it is crucial to understand the physiology of the mucociliary apparatus and how its components (cilia, mucus-periciliary layer and its interaction) affect the clearance of respiratory secretions. AIMS: This paper aims to review and to discuss different techniques for studying mucociliary transport and their clinical and experimental applicability. CONCLUSIONS: The methods listed in this revision provide us with valuable information about different aspects of the mucociliary transport. Some of the methods listed are more suitable for clinical practice and present reproducible results. Others, show only applicability in experimental settings due to technical difficulties or financial limitations. However, it is important to emphasize that up to now there is no method that can evaluate ciliary beating frequency (CBF) in vivo and in situ. Such a method would become a valuable tool in the scientific scenario and in the clinical practice, supporting the diagnosis of ciliary dyskinesias and avoiding the use of invasive procedures to corroborate the clinical suspicion.