Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants.
OBJECTIVE
Angiotensin-converting enzyme (ACE) gene contains a polymorphism consisting of either the presence (I) or absence (D) of a 287-bp 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.


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 (Pi(mean)/Pi(max)) × (T(i)/T(tot)), where Pi(mean) was the mean inspiratory pressure estimated from airway pressure, generated 100 ms after an occlusion (P(0.1)), Pi(max) was the maximum inspiratory pressure and T(i)/T(tot) was the ratio of the inspiratory time to the total respiratory cycle time. Pi(max) 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.


CONCLUSIONS
These results suggest that an association of ACE genotypes with PTImus measurements may exist in infants.
Dimitriou
Gabriel
G
Neonatal Intensive Care Unit, Department of Pediatrics, University of Patras Medical School, Rio, Patras, Greece. gdimitriou@med.upatras.gr
Papakonstantinou
Despina
D
Stavrou
Eleana F
EF
Tzifas
Sotirios
S
Vervenioti
Aggeliki
A
Athanassiadou
Aglaia
A
Mantagos
Stefanos
S
D005260:Female; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D001239:Inhalation / Q000502:physiology; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology*
D007703:Peptidyl-Dipeptidase A