Fetal expression of renin, angiotensinogen, and atriopeptin genes in chick heart

The renin-angiotensin and atriopeptin systems play important roles in the regulation of volume and fluid homeostasis. The two systems have opposing physiologic actions in a number of tissues. Experiments were performed to determine whether there were differences in the developmental expression of the genes for renin, angiotensinogen, and atriopeptin. Using RNA dot blot analysis, we compared levels of gene activity for renin, angiotensinogen, and atriopeptin in right atria, left atria, right ventricle, and left ventricle, from 18-day in ovum and 10-day old White Leghorn chicks. In 18-day embryonic chick heart there was expression of atriopeptin mRNA predominantly in the left and right ventricles. At this age, atriopeptin message was expressed in all four cardiac chambers, left ventricle greater than right ventricle greater than right atria greater than left atria. Renin and angiotensinogen mRNA was expressed in all cardiac chambers with reduced expression in left atria. In 10-day old chicks, renin, angiotensinogen, and atriopeptin mRNA was expressed in atrial tissue with right atria greater than left atria, with no detectable expression in left ventricle, right ventricle, or skeletal muscle. Beta actin was expressed in all four cardiac chambers and skeletal muscle, and was used to normalize signals. Cardiac expression of the genes for renin and angiotensinogen during embryogenesis suggests that the renin-angiotensin system may be involved in the growth and development of the myocardium.