Cardiac myocytes express mRNA for ten RGS proteins: changes in RGS mRNA expression in ventricular myocytes and cultured atria.

Regulators of G-protein signalling (RGS) are recently identified proteins that shorten the lifetime of the activated G protein. We now show that rat cardiac myocytes express mRNA for at least 10 RGS. The mRNA for RGS-r is barely detectable in rat ventricles, but increases more than 20-fold during the 60- to 90-min process of isolating ventricular myocytes, and after 90 min of culture of atrial pieces in medium with Ca2+. Both in myocytes and in atria, the rise in RGS-r is transient. The mRNA for cardiac RGS5, but not RGS-r, is developmentally regulated. These studies suggest that rapid regulation of RGS levels may be a new mechanism that governs how signals are transmitted across the cardiac cell membrane.