atrial-natriuretic-factor and zwittergent-3-12

Recent in vivo and in vitro studies in animals have demonstrated that cytokines of the IL-6 family are involved in cardiac hypertrophy and in protection of cardiomyocytes against apoptosis. The present study aims to analyse the capacity of human atrial cardiac cells (i.e., cardiomyocytes and fibroblasts) to display the gp130 receptor subunit, and to evaluate its functionality.. Twenty human atrial biopsies were used for immunohistochemistry, in situ hybridisation, and western blot analysis or dissociated for isolation and primary culture of cardiac cells.. Fibroblasts present in tissue or maintained in primary culture clearly express gp130 whereas the signal in cardiomyocytes is weaker. Culture of cardiac cells with a gp130 agonist antibody enhances atrial natriuretic peptide (ANP), beta myosin heavy chain (beta-MHC) expression in cardiomyocytes, and significantly increases the cell surface area microm(2)). This process could involve STAT3 (signal transducer and activator of transcription 3) phosphorylation.. These results demonstrate that gp130 activation in human cardiac cells leads to cardiomyocyte hypertrophy. We discuss several hypotheses on the role of IL-6-type cytokines on cardiomyocyte functions.

Topics: Aged; Analysis of Variance; Antibodies, Blocking; Antigens, CD; AraC Transcription Factor; Atrial Natriuretic Factor; Bacterial Proteins; Blotting, Western; Cardiomegaly; Cell Size; Cells, Cultured; Cytokine Receptor gp130; DNA-Binding Proteins; Fibroblasts; Fluorescent Antibody Technique, Indirect; Heart Atria; Humans; Immunohistochemistry; In Situ Hybridization; Interleukin-6; Membrane Glycoproteins; Middle Aged; Myocytes, Cardiac; Myosin Heavy Chains; Phosphorylation; Quaternary Ammonium Compounds; Receptors, Cytokine; Receptors, Interleukin-6; Repressor Proteins; STAT3 Transcription Factor; Trans-Activators; Transcription Factors

Particulate guanylate cyclase from bovine adrenal cortex can be stimulated by ANF. A 2-fold stimulation of the enzyme was obtained with 100 nM ANF and a half-maximal stimulation, with a 5 nM dose. The stimulation by ANF persisted for at least 30 min. Various detergents, such as Triton X-100, Lubrol PX, cholate, CHAPS, digitonin and zwittergent, stimulated several-fold the activity of particulate guanylate cyclase. However, only Triton X-100 dispersed particulate guanylate cyclase without affecting its response to ANF. The dose-response curve of ANF stimulation of the particulate and the Triton X-100 dispersed enzyme was similar. The dispersion of a fully responsive guanylate cyclase to ANF will help us to uncover the type of interactions between guanylate cyclase and ANF. It will also be used as a first step for the purification of an ANF-sensitive particulate guanylate cyclase.

Topics: Adrenal Cortex; Animals; Atrial Natriuretic Factor; Cattle; Enzyme Activation; Guanylate Cyclase; Octoxynol; Polyethylene Glycols; Quaternary Ammonium Compounds; Rats; Solubility