Poster Display L Dilated cardiomyopathy Sunday, 12 June 2005 27 114 A novel role of the sarcolemmal calcium pump in the regulation of the calcineurin/NFAT hypertrophic pathway in the heart M.H. Buch t , A.H. Maass 2, A. Pickard t , A. Rodriguez 3, S. Gillies t , S.J. Langer 4, L.A. Leinwand 4, J.M. Redondo 3, A.L. Armesilla t, L. Neyses t ]The University Of Manchester, Division Of Cardiology, Manchester, United Kingdom; 2 University of Wuerzburg, Department of Medicine, Wuerzburg, Germany; 3 Universidad Aut noma de Madrid, Centro de Biolog a Molecular, Madrid, Spain; 4 University of Colorado, Dept. Mol. Cell. and Develop. Biology, Boulder, United States of America Cardiac hypertrophy is a leading predictor of morbidity and mortality in heart failure. It has recently become clear that the calcineurin/nuclear factor of activated T-cell (NFAT) pathway has a central role in the de- velopment of cardiac hypertrophy. Emerging evidence places the sar- colemmal calcium pump, or plasma membrane calcium/calmodulin AT- Pase pump (PMCA), as a potential modulator of signal transduction pathways. We demonstrate a novel interaction between PMCA and the calcium/calmodulin dependent phosphatase, calcineurin, in mammalian cells by co-immunoprecipitation and western blot analysis. The inter- action domains were located to the catalytic domain of PMCA4b, an isoform known to be expressed in the heart, and the catalytic domain of the calcineurin A subunit. Calcineurin activity, measured indirectly by the transcriptional activity of its best characterized substrate, NFAT, was significantly inhibited by 60% in the presence of over-expressed PMCA4b. This inhibition was notably reversed by the co-expression of the PMCA4b interaction domain. Recruitment by PMCA4b of cal- cineurin to a low calcium environment may thus represent the basis of this effect. Examination of this functional interaction in rat neonatal cardiomyocytes demonstrated a marked reduction in the phenylephrine- mediated induction of calcineurin activity when cells were infected with an adenoviral construct encoding PMCA4b in a dose-dependent manner. Furthermore, phenylephrine-induced cardiomyocyte hypertro- phy was also significantly inhibited, reflected by a significant attenuation in protein synthesis and transcriptional activity of ANF. Further work is underway to examine the mechanism of inhibition and determine the spe- cific effect of this interaction on hypertrophic genes. This novel role of the sarcolemmal calcium pump provides a new dimension in our understand- ing of the calcineurin/NFAT pathway, and subsequent agonist-mediated cardiomyocyte hypertrophy. This may therefore represent a potential new therapeutic target in the treatment of myocardial hypertrophy. DILATED CARDIOMYOPATHY 116 Danon disease explains the phenotype in a family originally reported as XLCM L. Ku 1, M.RG. Taylor 1, E. Carniel 1, A. Di Lenarda 2, M.R. Bristow 1, J. Towbin 3, G. Sinagra 2, L. Mestroni 1 ] University of Colorado, Health Science, Colorado, United States of America; 2 "Ospedali Riuniti" and University, Department of Cardiology, Trieste, Italy; 3 Baylor College of Medicine, Houston, United States of America Background: Danon disease (DD) is an X-linked condition caused by mutations in the LAMP2 (Xq24) gene. The phenotype includes: hyper- trophic cardiomyopathy (HCM), Wolff-Parkinson-White (WPW) syn- drome and skeletal myopathy. In 1993, a family with X-linked dilated cardiomyopathy (DCM) and elevated CK enzymes was reported. Geno- typing of dystrophin (DMD) gene markers implicated the DMD locus (XLCM: OMIM#302045) but DMD deletion testing was negative. Methods: Over the past decade, 6 additional family members developed cardiac disease (most with HCM and WPW). Sequencing of DMD failed to identify a mutation. Due to the phenotypic similarity with DD, we studied this family for LAMP2 mutations. Results: We found a novel nucleotide deletion (delA1082 beta isoform) in exon 8 that predicts a frameshift, the addition of 15 novel amino acids, and a premature stop codon. The mutation segregates across 4 genera- tions, being present in 7 affected subjects and in 1 younger clinically unaffected female (a presumed carrier). The family phenotypes include: DCM in 1 female, HCM in 7 males; WPW in 7 males and 3 females; 4 males required transplantation before age 25. In contrast to previous reports, females in this family have ocular complications (retinal pig- mentary changes); eye disease in males is more severe (choroideremia, sudden loss of visual acuity). A skeletal muscle biopsy in a 13 month- old mutation-carrying male did not demonstrate the vacuolar myopathy typically described in DD. Conclusions: X-linked DCM and/or HCM associated with WPW that cannot conclusively be attributed to DMD mutations should be evaluated for LAMP2 mutations. Retinal pigmentary dystrophies, even in females, can be clinical clues to the diagnosis of DD. The absence of vacuolar myopathy, especially in young patients, does not exclude this diagnosis. 117 Feasibility and diagnostic accuracy of multidetector computed tomography coronary angiography in patients with dilated cardiomyopathy D. Andreini 1 , G. Pontone 2, M. Pepi 2, G. Ballerini 2, E. Nobili 2, A. Magini 2, RG. Agostoni 2 ] Centro Cardiologico Monzino, Cardiology, Milan, Italy; 2Centro Cardiologico "Monzino", IRCCS, Milan, Italy Introduction: the prevalence of coronary artery disease (CAD) in pa- tients with dilated cardiomyopathy (DCM) of unknown ethiology is ap- proximately 50% and therefore coronary angiography is mandatory. Re- cent studies with multidetector computed tomography (MDCT) showed very high level of sensibility in detecting CAD and MDCT may be pro- posed as a non-invasive screening test. Aim of the study: to evaluate the feasibility and accuracy of coronary imaging by MDCT in a population with DCM of unknown ethiology vs conventional coronary angiography. Materials and methods: 18 patients (13 males, 5 females; age 604-12 years) affected by DCM (ejection fraction: 36 4- 6%, end diastolic vol- ume: 168 4- 39 ml) in stable clinical conditions underwent to coronary angiography and coronary MDCT (separeted at least by 3 days for pre- vention of radiocontrast-induced nephropathy). MDCT images has been acquired by means of CT 16 layers (Light speed General Electric) and evaluated with multiple approach including volume rendering and vessel analysis. The degree of stenosis was estimated in 11 segments of coro- nary arteries: left main (LM), proximal, medium and distal left anterior descending (LAD), proximal, medium and distal left circumflex (LC), proximal, medium and distal rigth coronary artery (RCA) and posterior descending (PD). Results: At conventional coronary angiography 14 (77%) of cases had normal coronary arteries. All cases with normal (14) or pathological (4) coronary arteries were detected by MDCT, even though in 1 case a disparity in term of severity of stenosis was observed. MDCT visu- alised canalisation of all coronary artery segments with the exception of 1 case of distal left circumflex (LCX), 1 medium right coronary artery (RCA) and 1 posterior descending (PD). Overall feasibility of coronary artery visualisation was 98,5% (195 of 198 segments). In comparison to conventional angiography the sensitivity (Sn) and specificity (Sp) in the detection of the degree of stenosis was: LM: Sn 100%/Sp 94%, proximal LAD: 100%/100%, medium LAD: 100%/93%, distal LAD 100%/88%, proximal LC: 100%/100%, medium LC: 100%/100%, distal LC: 100%/100%, proximal RCA: 100%/91%, medium RCA: 100%/94%, distal RCA: 100%/94%, PD: 100%/100%. Conclusions: our preliminary results suggest that feasibility of evalua- tion of the entire coronary tree in the DCM is 98,5%. The absence of false negative in the detection of the degree of stenosis (sensitivity = 100% for all segments) could allow MDCT as screening test for detection of CAD in dilated cardiomyopathy.