[Changes in the composition of cardiac muscle myosin light chains during cardiac diseases].

In this paper our data of the study on composition of human cardiac myosin light chains in norm and its changes at different stages of dilated cardiomyopathy and heart valvular diseases are presented. Functional role and diagnostic value of these changes are discussed.

[Role of light chains of myosin in the regulation of contraction of vertebrate striated muscles].

The data of the study on Ca2+ sensitivity of ATPase activity of myosin from vertebrate striated muscles in the presence of actin and the conditions of its manifestation and disappearance are presented. The role of Ca2+ sensitivity of actin-activated myosin ATPase in the regulation of contraction of vertebrate striated muscles is discussed.

[Interaction of dopamine with artificial phospholipid membranes].

The interaction of dopamine (DA) with phospholipid membranes has been investigated. The membrane current in planar bilipid membrane (BLM) modified by amphotericin B in voltage clamp conditions under alternating polarity was shown to symmetrically increase 1.2 times when DA was added outside the BLM. This implies a uniform change of charge on each membrane surface and hence the diffusion of DA within the BLM and its exposure on the internal side. The appearance of single threads and bundles of filaments within the internal liposomal cavities was observed in the ultrastructure of suspended thin-walled liposomes filled with globular actin after the introduction of DA into external solution. This reshaped liposomes into rod-like, spindle-shaped or angular structures. Actin serves as a marker for DA due to its property to polymerize itself under the influence of DA. Thus, the structural reorganization of liposomes manifests the presence of DA inside them and the induction of actin polymerization.

[The myosin-activating protein kinases in human myocardium: localization and content].

Using the immunofluorescence approach, we have determined that the recently detected protein kinases, among which are RhoA-activated kinase, integrin-linked kinase, zipper interacting protein kinase, and death-associated protein kinase, which are capable of phosphorylating myosin, are localized in the Z-lines sarcomeres of human myocardium. Additionally, we studied the content of integrin-linked and zipper interacting protein kinases in human embryonic myocardium, as well as in normal and hypertrophic adult human heart. The content of these protein kinases in adult normal myocardium increases in comparison with the embryonic heart. The content of integrin-linked and zipper interacting protein kinases in hypertrophic myocardium is higher compared with the normal adult heart. The data obtained suggest the involvement of these protein kinases in the development and hypertrophy of human heart.

[Autoantibodies to light myosin chains as an early marker of damage to the myocardium].

The concentration of autoantibodies to myosin light chains in the blood serum of patients who have undergone operation on heart under conditions of artificial hypothermal circulation was measured after 3, 6, 9, 18, 24, 36 h following the reperfusion of myocardium. According to the postoperative data, the patients were divided into three groups: patients with stable hemodynamics in the postoperative period (group 1); patients with myocardial stunning following reperfusion of myocardium (group 2); and patients with severe heart failure that developed in early postoperative period (group 3). Significant differences in the concentration of autoantibodies to myosin light chains have been found between the groups. A high correlation was established between the duration of cross-clamping of aorta and the concentration of autoantibodies. By means of multivariant regression analysis, factors characterizing the initial severity of disease that can influence the concentration of autoantibodies to myosin light chains in blood have been revealed.