Nuclear membrane receptors and channels as targets for drug de...

The use of confocal microscopy has shown that the nucleus plays an important role in excitation-contraction and excitation-secretion coupling of several excitable and nonexcitable cardiovascular cells. It has shown that the nuclear membranes, like the sarcolemmal membrane, possess ionic transporters as well as G protein-coupled receptors (GPCRs), which play a major role in modulating both cytosolic and nuclear ionic homeostasis and nuclear signalling. During spontaneous contraction of heart cells, the increase in cytosolic Ca2+ was immediately followed by a transient increase in nuclear Ca2+. The nuclear Ca2+ rise during excitation-contraction and excitation-secretion coupling was both dependent and independent of changes in cytosolic Ca2+. Nuclear membrane GPCRs, such as those of angiotensin II, neuropeptide Y, and ET-1, were functional and contributed to modulation of nuclear ionic homeostasis via direct and (or) indirect modulation of nuclear membrane ionic transporters such as channels, pumps, and exchangers. The signalling of nuclear membrane GPCRs may also contribute to modulation of gene expression, which may regulate proliferation and remodelling of cells and, indeed, life and death. Direct or indirect targeting of nuclear membrane ionic transporters and GPCRs may constitute a new target for drug action.