Phosphodiesterases Expression during Murine Cardiac Development.

3'-5' cyclic nucleotide phosphodiesterases (PDEs) are a large family of enzymes playing a fundamental role in the control of intracellular levels of cAMP and cGMP. Emerging evidence suggested an important role of phosphodiesterases in heart formation, but little is known about the expression of phosphodiesterases during cardiac development. In the present study, the pattern of expression and enzymatic activity of phosphodiesterases was investigated at different stages of heart formation. C57BL/6 mice were mated and embryos were collected from 14.5 to 18.5 days of development. Data obtained by qRT-PCR and Western blot analysis showed that seven different isoforms are expressed during heart development, and PDE1C, PDE2A, PDE4D, PDE5A and PDE8A are modulated from E14.5 to E18.5. In heart homogenates, the total cAMP and cGMP hydrolytic activity is constant at the evaluated times, and PDE4 accounts for the majority of the cAMP hydrolyzing ability and PDE2A accounts for cGMP hydrolysis. This study showed that a subset of PDEs is expressed in developing mice heart and some of them are modulated to maintain constant nucleotide phosphodiesterase activity in embryonic and fetal heart.

Correlation of lung function and respiratory muscle strength with functional exercise capacity in obese individuals with obstructive sleep apnea syndrome.

OBJECTIVE: To evaluate lung function and inspiratory muscle strength, correlating them with exercise tolerance, in obese individuals with obstructive sleep apnea syndrome (OSAS). METHODS: The sample comprised 31 adult subjects with moderate-to-severe OSAS diagnosed by polysomnography. We used spirometry to measure FVC, FEV1, and FVC/FEV1 ratio, using pressure manometry to measure MIP and MEP. The incremental shuttle walk test (ISWT) and the six-minute walk test (6MWT) were used in order to determine functional exercise capacity. RESULTS: In this sample, the mean values for FVC (% of predicted), FEV1 (% of predicted): MIP, and MEP were 76.4 ± 12.3%, 80.1 ± 6.3%, 60.0 ± 21.9 cmH2O, and 81.3 ± 22.2 cmH2O, respectively. The mean distances covered on the ISWT and 6MWT were 221 ± 97 m and 480.8 ± 67.3 m, respectively. The ISWT distance showed moderate positive correlations with FVC (r = 0.658; p = 0.001) and FEV1 (r = 0.522; p = 0.003). CONCLUSIONS: In this sample of obese subjects with untreated OSAS, lung function, inspiratory muscle strength, and exercise tolerance were all below normal. In addition, we found that a decline in lung function, but not in respiratory muscle strength, was associated with exercise tolerance in these patients.

Correlation of lung function and respiratory muscle strength with functional exercise capacity in obese individuals with obstructive sleep apnea syndrome / Associação entre função pulmonar, força muscular respiratória e capacidade funcional de exercício em indivíduos obesos com síndrome da apneia obstrutiva do sono

ABSTRACT Objective: To evaluate lung function and inspiratory muscle strength, correlating them with exercise tolerance, in obese individuals with obstructive sleep apnea syndrome (OSAS). Methods: The sample comprised 31 adult subjects with moderate-to-severe OSAS diagnosed by polysomnography. We used spirometry to measure FVC, FEV1, and FVC/FEV1 ratio, using pressure manometry to measure MIP and MEP. The incremental shuttle walk test (ISWT) and the six-minute walk test (6MWT) were used in order to determine functional exercise capacity. Results: In this sample, the mean values for FVC (% of predicted), FEV1 (% of predicted): MIP, and MEP were 76.4 ± 12.3%, 80.1 ± 6.3%, 60.0 ± 21.9 cmH2O, and 81.3 ± 22.2 cmH2O, respectively. The mean distances covered on the ISWT and 6MWT were 221 ± 97 m and 480.8 ± 67.3 m, respectively. The ISWT distance showed moderate positive correlations with FVC (r = 0.658; p = 0.001) and FEV1 (r = 0.522; p = 0.003). Conclusions: In this sample of obese subjects with untreated OSAS, lung function, inspiratory muscle strength, and exercise tolerance were all below normal. In addition, we found that a decline in lung function, but not in respiratory muscle strength, was associated with exercise tolerance in these patients.

RESUMO Objetivo: Avaliar e correlacionar a função pulmonar e a força muscular inspiratória com a tolerância ao esforço em indivíduos obesos com síndrome de apneia obstrutiva do sono (SAOS). Métodos: Foram recrutados 31 adultos com diagnóstico de SAOS de moderada a grave através do exame de polissonografia. Os participantes foram submetidos à espirometria para a medida de CVF, VEF1 e relação CVF/VEF1, assim como à manovacuometria para a medida de PImáx e PEmáx. Para a determinação da capacidade funcional de exercício foram realizados o teste shuttle (TS) e o teste de caminhada de seis minutos (TC6). Resultados: Na amostra, as médias de CVF (% do previsto), VEF1 (% do previsto), PImáx e PEmáx foram de 76,4 ± 12,3%, 80,1 ± 6,3%, 60,0 ± 21,9 cmH2O e 81,3 ± 22,2 cmH2O, respectivamente. As médias das distâncias percorridas no TS e no TC6 foram de 221 ± 97 m e 480,8 ± 67,3 m, respectivamente. Houve correlações moderadas positivas entre a distância percorrida no TS e CVF (r = 0,658; p = 0,001) e entre a distância no TS e VEF1 (r = 0,522; p = 0,003). Conclusões: Nesta amostra de indivíduos obesos com SAOS não tratada, houve reduções na função pulmonar, força muscular inspiratória e capacidade física. Além disso, observou-se que o declínio da função pulmonar, mas não da força muscular respiratória, estava associado à tolerância ao esforço físico nestes pacientes.