Myocardium expression of connexin 43, SERCA2a, and myosin heavy chain isoforms are preserved in nitrofen-induced congenital diaphragmatic hernia rat model.
BACKGROUND
Previous morphological studies had produced controversial results with regard to heart development in congenital diaphragmatic hernia (CDH), whereas a few publications investigated cardiac function and myocardial maturation. Myocardium maturation is associated with age-dependent increasing of gene expression of gap junction protein connexin 43 (Cx43), adenosine triphosphatase of the sarcoplasmic reticulum (SERCA2a), as well as switching of myosin heavy chains (MHCs) from beta to alpha isoforms. Our aim was to evaluate myocardium maturity in nitrofen-induced CDH rat model.


METHODS
Fetuses from dated pregnant Sprague-Dawley rats were assigned to 3 experimental groups: control, nitrofen (exposed to nitrofen, without CDH), and CDH (exposed to nitrofen, with CDH). Myocardial samples collected from left ventricle free wall were processed to (i) quantification of messenger RNA (mRNA) of Cx43, SERCA2a, alpha and beta MHC isoforms, as well as beta-actin (housekeeping gene); and (ii) separation of MHC isoforms (alpha and beta isoforms) by sodium dodecyl sulfate polyacrylamide gel electrophoresis silver stained.


RESULTS
We demonstrated that there is no difference in myocardial gene expression of Cx43 (control, 1.0 +/- 0.1; nitrofen, 1.1 +/- 0.2; CDH, 1.3 +/- 0.2) and SERCA2a (control, 1.0 +/- 0.1; nitrofen, 0.9 +/- 0.1; CDH, 1.0 +/- 0.2). Myocardial gene expressions of alpha and beta mRNA of MHC isoforms were slightly decreased both in nitrofen and CDH fetuses when compared with control fetuses, but evaluation of the alpha-to-beta ratios of MHC isoforms at protein level revealed no significant differences between CDH and control (control, 16.9 +/- 2.5; CDH, 17.0 +/- 2.0).


CONCLUSIONS
Myocardial quantification of Cx43 and SERCA2a mRNA, as well as the expression pattern of MHC isoforms at protein levels, was similar in all studied groups. We predict, therefore, that acute heart failure commonly observed in CDH infants might be attributed predominantly to cardiac overload secondary to severe pulmonary hypertension rather than to myocardial immaturity.
Baptista
Maria João
MJ
Life and Health Sciences, Research Institute (ICVS), School of Health Sciences, University of Minho, 4709-057 Braga, Portugal.
Recamán
Mónica
M
Melo-Rocha
Gustavo
G
Nogueira-Silva
Cristina
C
Roriz
José-Mário
JM
Soares-Fernandes
João
J
Gonzaga
Silvia
S
Santos
Marta
M
Leite-Moreira
Adelino
A
Areias
José Carlos
JC
Correia-Pinto
Jorge
J
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000032:analysis*; D018031:Connexin 43 / Q000032:analysis*; D004195:Disease Models, Animal; D005260:Female; D005325:Fetal Organ Maturity / Q000187:drug effects; D006548:Hernia, Diaphragmatic / Q000139:chemically induced; D065630:Hernias, Diaphragmatic, Congenital; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000032:analysis*; D010575:Pesticides / Q000494:pharmacology; D010647:Phenyl Ethers / Q000494:pharmacology; D011247:Pregnancy; D020033:Protein Isoforms / Q000032:analysis; D051381:Rats; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
D018031:Connexin 43; D010575:Pesticides; D010647:Phenyl Ethers; D020033:Protein Isoforms; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D018995:Myosin Heavy Chains; D000252:Calcium-Transporting ATPases; C007350:nitrofen