A procedure for dissociating the rabbit aorta into single, functional smooth muscle cells is described. After removal of adventitia and intima, slices of media were incubated with purified collagenase, elastase, and soybean trypsin inhibitor in a Krebs-Ringer buffer modified with Hepes, amino acids, and a [Ca2+] of 0.2 mM. After enzymatic digestion and mechanical shear, the yield of dispersed cells was approximately 25% based on DNA recovered. Greater than 95% of the cells excluded trypan blue and approximately 80-90% adhered to tissue culture dishes. By phase contrast microscopy, most of the cells were elongate and approximately 10 micron X 30 micron in size. The remainder were either spherical or highly crenated and contracted. Electron microscopy of the cells showed that immediately after dissociation greater than 95% could be identified as smooth muscle, though most had undergone some degree of structural change compared to cells in situ. Depending on the preparation, from 5 to 50% of these cells contracted in response to agonists. Cells shortened by 10-15% and developed numerous evaginations when stimulated by angiotensin II norepinephrine, or carbamylcholine. Cells relaxed after washout of agonists and could subsequently be restimulated. Specific inhibitors of each of the agonists blocked the contractile response. Dispersed cells cultured for 1-5 days contracted in even higher numbers than the freshly prepared cells, suggesting restoration of hormone binding and/or contractile function in culture. This preparation provides a system in which the physiology of individual vascular smooth muscle cells may be studied.

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