Myocardium cell types

The FGF family consists of 23 proteins that are classified by their expression pattern, receptor-binding preference, and protein sequence (20,21). FGF is present in the normal myocardium (22). Its expression is stimulated by hypoxia (23) and hemodynamic stress (24). FGF-2 is a pluripotent molecule and modulates numerous cellular functions for multiple cell types. In the context of angiogenesis, it induces endothelial cell proliferation, survival, and differentiation, and is also involved in cell migration of endothelial cells, smooth muscle cells, macrophages, and fibroblasts (21). These effects are mediated through its interaction with the tyrosine kinase receptor FGFRI which also leads to the downstream release of NO (25). Additionally, FGF-2 stimulates endothelial cells to produce a... 

Looking at the results of both preclinical and clinical studies, we recognize the potential of cardiac cell transplantation to alter outcomes. However, we have to admit that in most cases, we do not understand how different cell types improve LV function. Increases in microvascular density, diastolic and systolic function, and an attenuated remodeling, are all reported after the application of many different cell types, but the exact mechanisms are unclear. Only a few studies address the elec-trophysiologic fate of the injected cells (71,72). In these studies, skeletal myoblasts were found to be isolated from the surrounding myocardium, and they underwent severe... 

Some studies conducted over the past two decades have provided evidence that the ventricular myocardium may comprise three electrophysiological and functionally distinct cell types in some species epicardial, M, and endocardial cells.15 Ventricular epicardial, but not endocardial, cells generally display a prominent phase 1 because of a large 4-aminopyridine-sensitive transient outward current (Ito), giving the action potential a notched configuration. Differences in the... 

Stem cells from a number of sources have been explored for regenerating the myocardium. Both multi-potent adult stem cells and pluripotent embryonic stem (ES) cells have been used to generate vascular cells and cardiac myocytes for therapy (Figure 34.3). A number of clinical studies have explored adult stem cells for their therapeutic potential in treating ischemic heart disease. While ES cells have only been investigated to date in preclinical models, a new clinical study is expected to assess safety of ES cell transplantation (Alper, 2009). In addition to stem cells, adult skeletal muscle cells have also been explored for clinical cardiac cell therapy. Each cell type is briefly reviewed in the context of myocardium regeneration. 

Mechanism of Action An amide-type local anesthetic that shortens the action potential duration and decreases the effective refractory period and automaticity in the His-Purkinje system of the myocardium by blocking sodium transport across myocardial cell membranes. Therapeutic Effect Suppresses ventricular arrhythmias. Pharmacokinetics Very rapidly and completely absorbed following PO administration, Protein binding 10%, Metabolized in liver. Excreted in urine. Half-life 15 hr. 

It is a reduction/decrease in the activity of specialized cells. For example barbiturates depress central nervous system, quinidine depresses myocardium. Certain drugs stimulate one type of cells but depress others e.g. morphine stimulates the vagus and chemoreceptor trigger zone but depresses the vomiting and cough centres. Similarly acetylcholine stimulates intestinal smooth muscle but depresses SA node in the heart. 

Adrenoceptor subtypes mediate negative inotropy in myocardium from a1A/c-knockout and wild type mice. J Mol Cell Cardiol 2002 34 1007-1017. 

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