This program project is directed at understanding the cellular and molecular mechanisms linking stimulation to contraction of smooth muscle. This issue will be addressed by a team of scientists utilizing the tools of Biophysics, Physiology, Molecular Biology, Biochemistry, and Cell Biology. The objective of this program will be addressed by four distinct projects and will be supported by two core facilities. Project 1 is directed at understanding the role of protein kinase C and calmodulin-dependent protein kinase II in regulating [Ca2+] within single smooth muscle cells. This will be accomplished by determining the effect of selectively activating or inhibiting specific protein kinases on both calcium entry and calcium re-uptake processes. Project 2 has two distinct aims: 1. Determination of the ionic events underlying stretch- activated contraction of smooth muscle; and, 2. Determination of the ionic and metabolic events underlying spontaneous membrane potential oscillations. Project 3 is directed at defining the structure/activity relationship of smooth muscle protein kinase C and in determining the effect of both protein kinase C and calmodulin-dependent protein kinase II on proteins responsible for calcium regulation (calcium pumps, calcium channels) in smooth muscle. Project 4 is directed at determining changes in the organization of molecules that comprise the contractile apparatus of smooth muscle underlying contraction. Specifically, changes in the structure and organization of actin, myosin, calponin, and caldesmon will be investigated. The activities in these projects will be supported by an Administrative Core and a Biophysics Core providing advanced instrumentation and support for electrophysiology, digital imaging microscopy, the use of caged photoactivatable compounds, and the analysis of electron micrographs. It is anticipated that these projects and cores will provide new insights into: 1. The role of ions, second messengers and protein kinases in the regulation of ion channels; 2. Mechanisms of control of cytoplasmic calcium and 3. Mechanisms of activation of the contractile machinery.