Regulation of alpha-smooth muscle actin expression in adult cardiomyocytes through a tyrosine kinase signal transduction pathway

An Improved Method of Maintaining Primary Murine Cardiac Fibroblasts in Two-Dimensional Cell Culture

Primary cardiac fibroblasts are notoriously difficult to maintain for extended periods of time in cell culture, due to the plasticity of their phenotype and sensitivity to mechanical input. In order to study cardiac fibroblast activation in vitro, we have developed cell culture conditions which promote the quiescent fibroblast phenotype in primary cells. Using elastic silicone substrata, both rat and mouse primary cardiac fibroblasts could be maintained in a quiescent state for more than 3 days after isolation and these cells showed low expression of myofibroblast markers, including fibronectin extracellular domain A, non-muscle myosin IIB, platelet-derived growth factor receptor-alpha and alpha-smooth muscle actin. Gene expression was also more fibroblast-like vs. that of myofibroblasts, as Tcf21 was significantly upregulated, while Fn1-EDA, Col1A1 and Col1A2 were markedly downregulated. Cell culture conditions (eg. serum, nutrient concentration) are critical for the control of temporal fibroblast proliferation. We propose that eliminating mechanical stimulus and limiting the nutrient content of cell culture media can extend the quiescent nature of primary cardiac fibroblasts for physiological analyses in vitro.

Cardiac dysfunction and inefficiency after substrate-enriched warm blood cardioplegia

OBJECTIVE

The study assessed the outcome after prolonged warm continuous antegrade blood cardioplegia (WCBC) with substrate enrichment, in terms of mechanical performance and mechanoenergetic efficiency.

METHODS

WCBC was given for 3 h to three groups of pigs on cardiopulmonary bypass; WCBC alone (n=7), WCBC+glucose and insulin (+GIK, n=7) and WCBC+L-glutamine (+GLN, n=7). Cardiac systolic and diastolic function, pressure-volume area (PVA) and myocardial oxygen consumption (MVO(2)) were assessed before, and twice after WCBC using pressure-conductance catheter, coronary flow-probes and O(2)-content difference.

RESULTS

In the WCBC, +GIK and +GLN groups respectively, the following parameters decreased after WCBC compared to baseline: left ventricular developed pressure by 26, 19 and 25% (P<0.001); dP/dt(max) by 36, 37 and 34% (P<0.001); preload recruitable stroke work by 35, 41 and 28% (P<0.001); mechanoenergetic efficiency (PVA/MVO(2)) by 44, 41 and 22% (P<0.001). End-diastolic stiffness increased early after WCBC in the WCBC and +GLN groups, while it was unchanged in the +GIK group (P=0.032).

CONCLUSION

Despite continuous aerobic conditions and additional substrates, post-WCBC cardiac contractile function and mechanoenergetic efficiency was severely depressed. The results demonstrate the hazards of sustained normothermic hyperkalemic perfusion.

Effect of antioxidants, resveratrol, quercetin, and N-acetylcysteine, on the functions of cultured rat hepatic stellate cells and Kupffer cells

Effects of antioxidants, resveratrol, quercetin, and N-acetylcysteine (NAC) on the functions of cultured rat hepatic stellate cells and Kupffer cells were studied. These compounds dose-dependently suppressed serum-dependent proliferation of stellate cells as determined by [3H]thymidine and 5-bromo-2'-deoxyuridine uptake. Expression of smooth muscle alpha-actin was suppressed by a high dose of resveratrol and quercetin. These phenolic compounds also suppressed inositol phosphate metabolism, tyrosine phosphorylation, and mitogen-activated protein (MAP) kinase activation in platelet-derived growth factor/BB-stimulated stellate cells. Moreover, the phenolic compounds selectively reduced the level of cell cycle protein cyclin D1 in stellate cells. Thus, resveratrol and quercetin might inhibit stellate cell activation by perturbing signal transduction pathway and cell cycle protein expression, whereas mechanism of potent antiproliferative effect of NAC remains to be elucidated. On the other hand, kinetic analysis showed that production of nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) by lipopolysaccharide-stimulated Kupffer cells was strongly inhibited by resveratrol and quercetin but not by NAC. Although expression of messenger RNAs for inducible NO synthase and TNF-alpha was not affected by the phenolic compounds, cellular levels of inducible NO synthase and TNF-alpha secretion were suppressed significantly, indicating the posttranscriptional process of generating these proteins might be affected predominantly by these phenolic compounds. Thus, NAC and these phenolic compounds may have therapeutic potential against liver injury by regulating functions of hepatic stellate cells and Kupffer cells.