279 Right ventricular metabolic imaging in experimental pulmonary artery hypertension

Abstract

fore, wild type and mutant L29Q cTn were reconstituted with the pseudo-phosphorylated S22D/S23D cTnI that mimics the native phosphorylated state to determine the mechanism of FHC and its effect on cardiac function. METHODS/RESULTS: To monitor the differences of the calcium binding affinity for the wild type and the mutant cTn, a novel cTnC construct (cTnC) labelled with IAANS molecule was used. Upon a series of calcium titrations, the IAANS-fluorescence changes induced by different cTn complexes were measure by a Cary Eclipse spectrophotometer. Our current results indicate that the L29Q mutation increases the calcium binding affinity of cTn, consistent with previous findings. However, contrary to previous findings, the pseudo-phosphorylated cTnI appears to increase calcium binding affinity for the wild type cTn. In addition, this increased of calcium binding affinity caused by the pseudo-phosphorylated cTnI is not observed in L29Q cTn, suggesting that the interaction between cTnC and cTnI may be disrupted by the L29Q mutation. CONCLUSION: Our fluorescence study shows that the reconstituted L29Q cTn has an overall higher calcium binding affinity than that of the wild type cTn. In addition, the presence of the pseudo-phosphorylated cTnI increases the calcium affinity only for the wild type cTn but not for the L29Q cTn. This suggests that L29Q mutation may potentially disrupt the interaction between cTnC and cTnI and thus leads to the impaired cardiac relaxation pertain to the etiology of FHC. Heart and Stroke Foundation of BC & Yukon