Cavopulmonary anastomosis induces pulmonary expression of the angiotensin II receptor family.
ABSTRACT Cavopulmonary anastomosis is used for palliation of cyanotic cardiac lesions. Postoperative development of pulmonary arteriovenous malformations can be significant in 10% to 25% of patients. To study the basis for formation of arteriovenous malformations, we developed an ovine model that reliably induces their development 8 weeks after cavopulmonary anastomosis. Previously, we found that cavopulmonary anastomosis inhibits the expression of pulmonary angiotensin-converting enzyme and suppresses angiotensin II production.
This study examines the role of the angiotensin II receptors, type 1 and type 2, in this setting of pulmonary vascular remodeling.
Lambs, aged 40 to 50 days, underwent cavopulmonary anastomosis. In age-matched control animals, a sham operation was performed. Messenger RNA and protein expression in lung specimens was measured at successive time points after cavopulmonary anastomosis or sham operations (n = 3 at each time point).
Angiotensin type 1 mRNA was maximally upregulated 2-fold at 5 weeks after cavopulmonary anastomosis (P =.006). Expression of angiotensin type 1 protein was increased at least 2-fold at 2, 5, and 15 weeks after cavopulmonary anastomosis (P =.005). Cavopulmonary anastomosis also increased angiotensin type 2 mRNA and protein expression at least 2-fold at 2 and 5 weeks (P =.02) after surgical intervention. At 15 weeks, expression of angiotensin type 2 mRNA and protein was unchanged from that seen in control animals. Immunolocalization in pulmonary tissue sections 2 weeks after cavopulmonary anastomosis revealed markedly enhanced staining of angiotensin II receptor type 1 in vascular smooth muscle and angiotensin II receptor type 2 in the endothelium of pulmonary arteries.
Rapid elevation in the expression of the type 1 and 2 angiotensin II receptors in the affected pulmonary vasculature after cavopulmonary anastomosis suggests their involvement in the pathologic vascular remodeling that occurs after cavopulmonary anastomosis.
SourceAvailable from: Minoo Kavarana[Show abstract] [Hide abstract]
ABSTRACT: Children with functional single ventricle heart disease are commonly palliated down a staged clinical pathway toward a Fontan completion procedure (total cavopulmonary connection). The Fontan physiology is fraught with long-term complications associated with lower body systemic venous hypertension, eventually resulting in significant morbidity and mortality. The bidirectional Glenn shunt or superior cavopulmonary connection (SCPC) is commonly the transitional stage in single ventricle surgical management and provides excellent palliation. Some studies have demonstrated lower morbidity and mortality with the SCPC when compared with the Fontan. Unfortunately the durability of the SCPC is significantly limited by the development of pulmonary arteriovenous malformations (PAVMs) which have been commonly attributed to the absence of hepatic venous blood flow and the lack of pulsatile flow to the affected lungs. Abnormal angiogenesis has been suggested as a final common pathway to PAVM development. Understanding these fundamental mechanisms through the investigation of angiogenic pathways associated with the pathogenesis of PAVMs would help to develop medical therapies that could prevent or reverse this complication following SCPC. Such therapies could improve the longevity of the SCPC, potentially eliminate or significantly postpone the Fontan completion with its associated complications, and improve long-term survival in children with single ventricle disease.Expert Review of Cardiovascular Therapy 04/2014; DOI:10.1586/14779072.2014.912132
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ABSTRACT: Longevity of the superior cavopulmonary connection (SCPC) is limited by the development of pulmonary arteriovenous malformations (PAVM). The goal of this study was to determine whether phenotypic changes in pulmonary artery endothelial cells (PAEC) that favor angiogenesis occur with PAVM formation. A superior vena cava to right pulmonary artery connection was constructed in 5 pigs. Pulmonary arteries were harvested at 6 to 8 weeks after surgery to establish cultures of PAEC and smooth muscle cells, to determine cell proliferation, gene expression, and tubule formation. Abundance of proteins related to angiogenesis was measured in lung tissue. Contrast echocardiography revealed right-to-left shunting, consistent with PAVM formation. While the proliferation of smooth muscle cells from the right pulmonary artery (shunted side) and left pulmonary artery (nonshunted side) were similar, right PAEC proliferation was significantly higher. Expression profiles of genes encoding cellular signaling proteins were higher in PAECs from the right pulmonary artery versus left pulmonary artery. Protein abundance of angiopoietin-1, and Tie-2 (angiopoietin receptor) were increased in the right lung (both p < 0.05). Tubule formation was increased in endothelial cells from the right pulmonary artery compared with the left pulmonary artery (404 ± 16 versus 199 ± 71 tubules/mm(2), respectively; p < 0.05). These findings demonstrate that PAVMs developed in a clinically relevant animal model of SCPC concomitantly with differential changes in PAEC proliferative ability and phenotype. Moreover, there was a significant increase in the angiopoietin/Tie-2 complex in the right lung, which may provide novel therapeutic targets to attenuate PAVM formation after a SCPC.The Annals of thoracic surgery 08/2013; 96(4). DOI:10.1016/j.athoracsur.2013.05.075 · 3.65 Impact Factor