Myosin heavy chain and cardiac troponin T damage is associated with impaired myofibrillar ATPase activity contributing to sarcomeric dysfunction in Ca-paradox rat hearts.

This study aimed to explore the potential contribution of myofibrils to contractile dysfunction in Ca-paradox hearts. Isolated rat hearts were perfused with Krebs-Henseleit solution (Control), followed by Ca-depletion, and then Ca-repletion after Ca-depletion (Ca-paradox) by Langendorff method. During heart perfusion left ventricular developed pressure (LVDP), end-diastolic pressure (LVEDP), rate of pressure development (+ dP/dt), and pressure decay (-dP/dt) were registered.

Heme-induced contractile dysfunction in human cardiomyocytes caused by oxidant damage to thick filament proteins.

Intracellular free heme predisposes to oxidant-mediated tissue damage. We hypothesized that free heme causes alterations in myocardial contractility via disturbed structure and/or regulation of the contractile proteins. Isometric force production and its Ca(2+)-sensitivity (pCa50) were monitored in permeabilized human ventricular cardiomyocytes.

Myeloperoxidase impairs the contractile function in isolated human cardiomyocytes.

We set out to characterize the mechanical effects of myeloperoxidase (MPO) in isolated left-ventricular human cardiomyocytes. Oxidative myofilament protein modifications (sulfhydryl (SH)-group oxidation and carbonylation) induced by the peroxidase and chlorinating activities of MPO were additionally identified. The specificity of the MPO-evoked functional alterations was tested with an MPO inhibitor (MPO-I) and the antioxidant amino acid Met.

Single acute stress-induced progesterone and ovariectomy alter cardiomyocyte contractile function in female rats.

Aim: To assess how ovarian-derived sex hormones (in particular progesterone) modify the effects of single acute stress on the mechanical and biochemical properties of left ventricular cardiomyocytes in the rat.

Methods: Non-ovariectomized (control, n=8) and ovariectomized (OVX, n=8) female rats were kept under normal conditions or were exposed to stress (control-S, n=8 and OVX-S, n=8). Serum progesterone levels were measured using a chemiluminescent immunoassay.

Differences in angiotensin convertase enzyme (ACE) activity and expression may contribute to shorter event free period after coronary artery bypass graft surgery.

Aims: The goal of this study was to investigate the importance of the vascular angiotensin convertase enzyme (ACE) in coronary artery bypass graft surgery (CABG) patients.

Methods: Vascular tissue (distal saphenous vein [n= 163] and/or radial artery [n= 120] segments) and blood samples were collected from CABG patients (n= 81). We studied (i) the potency of angiotensin I (AngI) and angiotensin II (AngII) to evoke vascular contractions; (ii) vascular and plasma ACE concentrations; and (iii) ACE genotype of the patients enrolled.