Shortening velocity and myosin heavy- and light-chain isoform mRNA in rabbit arterial smooth muscle cells

smooth muscle cells (SMCs) isolated from rabbit carotid, femoral, and saphenous arteries, relative myosin isoform mRNA levels were measured in RT-PCR to test for correla-tions between myosin isoform expression and unloaded shortening velocity. Unloaded shortening velocity and per-cent smooth muscle myosin heavy chain 2 (SM2) and myosin light chain 17b (MLC17b) mRNA levels were not significantly different in single SMCs isolated from the luminal and adlu-minal regions of the carotid media. Saphenous artery SMCs shortened significantly faster (P 0.05) than femoral SMCs and had more SM2 mRNA (P 0.05) than carotid SMCs and less MLC17b mRNA (P 0.001) and higher tissue levels of SMB mRNA (P 0.05) than carotid and femoral SMCs. No correlations were found between percent SM2 and percent MLC17b mRNA levels and unloaded shortening velocity i