Detection of mRNA encoding H-1 receptor and iNOS by RT-PCR in autoimmune myocarditis with special reference to changes in heart contractility

Cardiac tissue from autoimmune myocarditis mice was studied to evaluate the expression and biological activity of mRNA encoding H-1 receptor and iNOS. BALB/c inbred mice were immunized with heart protein and sacrificed at 20, 45 and 50 days post immunization. Heart contractility studies and RT-PCR a ssays were performed. Heart from autoimmune myocarditis mice show mRNA iNOS -related dysfunction with a decrease in heart contractility. This effect wa s accompanied with an increase production of cyclic GMP and was improved by treating autoimmune mice with an inhibitor of iNOS activity. In addition, autoimmune myocardium expressed an active histamine H-1 receptor mRNA coupl ed to phospholipase C. The activation of H-1 receptor by ThEA stimulated bo th phosphoinositide hydrolysis and heart contractility. Normal myocardium d id not expressed neither iNOS mRNA nor H-1 receptor mRNA. In conclusions: t he development of autoimmune cardiac dysfunction was associated with the ex pression of iNOS mRNA, cyclic GMP accumulation and the expression of an act ive histamine H-1 receptor mRNA with increase production of inositol phosph ates. These protein emergence during the course of autoimmune myocarditis m ay be involved a distinct compensatory mechanism operating in this disease. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.