Extracellular matrix: differential influence on growth and biosynthesis patterns of vascular smooth muscle cells from SHR and WKY rats.

Smooth muscle cells from spontaneously hypertensive rats (SHR) elaborated extracellular matrix (ECM) material in culture that was more stimulatory to growth of cells from normotensive (WKY) animals than their own matrix. Both cell types elaborated ECMs consisting of glycoconjugate material (proteoglycans, glycopeptides) elastin, and collagens, but there were differences in the relative proportions of the compounds synthesized. Cells from SHR produced an ECM richer in elastin than that synthesized by WKY derived cells (approximately 19% vs. 11%, respectively). However, the latter elaborated ECMs containing more (approximately 45% for WKY vs. 29% for SHR) glycoconjugate material than the former. The lysyloxidase-mediated cross-linking of elastin was more rapid in cultured cells from SHR animals than from their normotensive counterparts and may be as a consequence of increased substate (tropoelastin) availability in ECMs from SHR animals. The relative proportions and sulphate levels of the glycosaminoglycans associated with matrix material elaborated by the two cell types were similar. Radiolabelled glycoconjugate material was degraded by cells (SHR/WKY) when they were plated upon pre-formed ECMs, and their patterns of synthesis of new matrix was markedly altered under such conditions. New matrix material elaborated by cells plated upon ECM-coated dishes consisted predominantly of glycopeptide and proteoglycan matrix components. Epidermal growth factor promoted the incorporation of [3H]-thymidine into DNA by quiescent cells, and this was also markedly stimulated when cells were plated onto ECM-coated plasticware rather than onto plastic substratum.