Effects Of Ouabain On Myocardial Cytoskeleton And Ultrastructure During The Development Of Ventricular Hypertrophy

Objective:To investigate the impairment of myocardial cytoskeleton and ultrastructure during the development of ouabain-induced ventricular hypertrophy.Methods:Forty male Spargue-Dawley(SD) rats were randomized into two groups: the ouabain group(n=20) received ouabain(27.8ug/kg/d) intraperitoneally and the control group(n=20) received saline instead. The systolic blood pressure (SBP) was measured by tail-off plethysmograph weekly. At the end of the third week and the sixth week, the rats were sacrificed respectively. Blood samples were collected to measure plasma ouabain levels by enzyme-linked immunosorbent assay (EL1SA). Myocardial ultrastructure was observed by transmission electron microscopy. The mRNA levels of Profilin-1,Desmin, PCNA,TGF-β1,ET-1in the ventricular myocardium were examined by real-time quantitative polymerase chain reaction (RT-PCR), and the protein levels were detected by immunohistochemisrty or Western blot.Result:At the end of the third week, there was no significant difference not only in the mean systolic blood pressure (SBP), but also the mRNA levels and protein expression of PCNA,TGF-β1and ET-1between two groups. However the rats of ouabain group showed the increased collagen, swelling mitochondria, elongated nuclei, convoluted nuclear membranes and condensed chromatin. Upregulation of Pro film-1and downregulation of Desmin were found in the ouabain group by RT-PCR and Western blot. At the end of sixth week, the ouabain group suffer from the developed mean systolic blood pressure (SBP), and even showed much more collagen, ruptured myofibrils, absence of the Z-disc, blurred cristae of mitochondria, deformed nuclei and blocked chromatin. The results of RT-PCR and Western blot displayed the upregulation of PCNA.TGF-β1,ET-1and the further changes of Profilin-1and Desmin.Conclusion:During ouabain-induced ventricular hypertrophy, the impairment of ultrastructure and cytoskeleton occured before the developed systolic blood pressure (SBP), even before the release of factors which is associated with hypertrophy. It revealed that ouabain played an directly noxious impact on the myocardia independent of hypertrophic factors. As result, reserchers will focus on early time of cardiovascular diseases such as essential hypertention, coronary atherosclerosis and heart failure before the disorganization of ultrastructure and cytoskeleton.