Angiotensin converting enzyme gene polymorphism and respiratory muscle function in infants
Résumé
Objective: Angiotensin converting enzyme (ACE) gene contains a polymorphism consisting of either the presence (I) or absence (D) of a 287 base pair fragment. Recent studies have suggested that the I-allele may be associated with superior exercise endurance; respiratory muscle function may be similarly influenced. The pressure-time index of inspiratory muscles (PTImus) is a measure of the load-capacity ratio of the inspiratory muscles. The objective of this study was to determine whether infants homozygous for the I-allele have lower PTImus compared to infants homozygous for the D-allele or heterozygous I/D. Patients and Methods: One hundred thirty two infants were studied. ACE genotyping was performed by polymerase chain reaction amplification using DNA from peripheral blood. PTImus was calculated as (Pimean/Pimax)x(Ti/Ttot), where Pimean was the mean inspiratory pressure estimated from airway pressure, generated 100 milliseconds after an occlusion (P0.1), Pimax was the maximum inspiratory pressure and Ti/Ttot was the ratio of the inspiratory time to the total respiratory cycle time. Pimax was the largest pressure generated during brief airway occlusions performed at the end of a spontaneous crying effort. Results: Infants with I/I genotype had significantly lower PTImus than infants with either D/D or I/D genotypes (p=0.000007). ACE genotype was significantly related (p=0.005) to PTImus measurements independent of other factors that may affect respiratory muscle function. Conclusion: These results suggest that an association of ACE genotypes with PTImus measurements may exist in infants.
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