ORIGINAL CONTRIBUTION Distinct mechanisms for diastolic dysfunction in diabetes mellitus and chronic pressure-overload Ine ˆs Falca ˜o-Pires • Giuseppina Palladini • Na ´dia Gonc ¸alves • Jolanda van der Velden • Daniel Moreira-Gonc ¸alves • Daniela Miranda-Silva • Francesco Salinaro • Walter J. Paulus • Hans W. M. Niessen • Stefano Perlini • Adelino F. Leite-Moreira Received: 23 August 2010 / Revised: 7 March 2011 / Accepted: 20 April 2011 / Published online: 1 May 2011 Ó Springer-Verlag 2011 Abstract Chronic pressure-overload and diabetes melli- tus are two frequent disorders affecting the heart. We aimed to characterize myocardial structural and functional changes induced by both conditions. Pressure-overload was established in Wistar-han male rats by supra-renal aortic banding. Six-weeks later, diabetes was induced by strep- tozotocin (65 mg/kg,ip), resulting in four groups: SHAM, banding (BA), diabetic (DM) and diabetic-banding (DB). Six-weeks later, pressure–volume loops were obtained and left ventricular samples were collected to evaluate altera- tions in insulin signalling pathways, extracellular matrix as well as myofilament function and phosphorylation. Pres- sure-overload increased cardiomyocyte diameter (BA 22.0 ± 0.4 lm, SHAM 18.2 ± 0.3 lm) and myofilament maximal force (BA 25.7 ± 3.6 kN/m 2 , SHAM 18.6 ± 1.4 kN/m 2 ), Ca 2? sensitivity (BA 5.56 ± 0.02, SHAM 5.50 ± 0.02) as well as MyBP-C, Akt and Erk phosphor- ylation, while decreasing rate of force redevelopment (K tr ; BA 14.9 ± 1.1 s -1 , SHAM 25.2 ± 1.5 s -1 ). At the extracellular matrix level, fibrosis (BA 10.8 ± 0.9%, SHAM 5.3 ± 0.6%), pro-MMP-2 and MMP-9 activities increased and, in vivo, relaxation was impaired (s; BA 14.0 ± 0.9 ms, SHAM 12.9 ± 0.4 ms). Diabetes increased cardiomyocyte diameter, fibrosis (DM 21.4 ± 0.4 lm, 13.9 ± 1.8%, DB 20.6 ± 0.4 lm, 13.8 ± 0.8%, respec- tively), myofilament Ca 2? sensitivity (DM 5.57 ± 0.02, DB 5.57 ± 0.01), advanced glycation end-product deposition (DM 4.9 ± 0.6 score/mm 2 , DB 5.1 ± 0.4 score/mm 2 , SHAM 2.1 ± 0.3 score/mm 2 ), and apoptosis, while decreasing K tr (DM 13.5 ± 1.9 s -1 , DB 15.2 ± 1.4 s -1 ), Akt phosphorylation and MMP-9/TIMP-1 and MMP-1/ TIMP-1 ratios. Diabetic hearts were stiffer (higher end- diastolic-pressure: DM 7.0 ± 1.2 mmHg, DB 6.7 ± 0.7 mmHg, SHAM 5.3 ± 0.4 mmHg, steeper end-diastolic- pressure–volume relation: DM 0.59 ± 0.18, DB 0.83 ± 0.17, SHAM 0.41 ± 0.10), and hypo-contractile (decreased end-systolic-pressure-volume-relation). DB animals presented further pulmonary congestion (Lungs/ body-weight: DB 5.23 ± 0.21 g/kg, SHAM 3.80 ± 0.14 g/kg) as this group combined overload-induced relaxation abnormalities and diabetes-induced stiffness. Diabetes mellitus and pressure overload led to distinct diastolic dysfunction phenotypes: while diabetes promoted myo- cardial stiffening, pressure overload impaired relaxation. The association of these damages accelerates the progres- sion of diastolic heart failure progression in diabetic- banded animals. Keywords Diabetes mellitus Á Diastolic function Á Hypertrophy Á Myocardial stiffness Á Pressure-overload Á Relaxation I. Falca ˜o-Pires Á N. Gonc ¸alves Á D. Moreira-Gonc ¸alves Á D. Miranda-Silva Á A. F. Leite-Moreira (&) Department of Physiology and Cardiothoracic Surgery, Cardiovascular R&D Unit, Faculty of Medicine, University of Porto, Alameda Professor Herna ˆni Monteiro, 4200-319 Porto, Portugal e-mail: amoreira@med.up.pt G. Palladini Á F. Salinaro Á S. Perlini Clinica Medica II, Fondazione IRCCS San Matteo, Universita ` di Pavia, Pavia, Italy J. van der Velden Á W. J. Paulus Department of Physiology, Institute for Cardiovascular Research, Vrije University Medical Center Amsterdam, Amsterdam, The Netherlands H. W. M. Niessen Pathology and Surgery, Vrije University Medical Center, Amsterdam, The Netherlands 123 Basic Res Cardiol (2011) 106:801–814 DOI 10.1007/s00395-011-0184-x