While diagnostic technology affords a more-refined awareness for the clinical indication known as hypertension and cerebrovascular disease, the molecular and cellular mechanisms that underly cerebrovascular pathophysiology are ill-defined. Moreover, little is known regarding the role the microvasculature plays in the etiology of these disease processes. Morphologic, biochemical and molecular studies using specific antibody and recombinant DNA probes will be implemented in model systems to determine whether extracellular matrix-cytoskeletal interactions modulate microvascular pericyte contractility and growth or endothelial cell response to injury, events believed central to cerebrovascular disease development. The molecular and cellular composition of normal, (Wistar-Kyoto) and spontaneously-hypertensive rat brain microvessels will be studied and characterized in situ prior to, coincident with and following hypertensive-onset. Wistar-Kyoto, spontaneously-hypertensive rat microvascular cells and their extracellular matrices will be isolated and characterized in vitro. Rat brain microvascular endothelial cell-extracellular matrices will be used as substrates to study pericyte and endothelial growth or motility following injury. Blocking with antibodies or digesting extracellular matrices with enzymes will reveal the molecular domains that modulate pericyte and endothelial cell behaviors. Labeled antibodies will be used to localize the form and detailed cytoskeletal array of cells grown on these biomatrices. Brain pericytes and endothelial cells that grow or recover from injury on vascular-derived extracellular matrices will be fractionated into soluble and insoluble cytoskeletal components prior to immunoprecipitation, electrophoresis and fluorographic analyses. mRNAs encoding cytoskeletal protein isoforms and extracellular matrix molecules will be characterized by Northern blot analysis using cDNA probes. Results of these experiments will not only reveal how cytoskeletal, extracellular matrix protein and mRNA metabolism modulate cerebrovascular cell behavior, but may ultimately reveal the molecular and cellular mechanisms that control the anomalous flow of blood seen in patients with cerebrovascular disorders.