Differential expression and secretion of CatA and EC-SOD by CMs and CFs. CMs and CFs were isolated from 4- to 6-day-old Sprague-Dawley rats of mixed sex. A, Western blot analysis demonstrating cellular protein expression of CatA in isolated neonatal CMs and in CFs. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) served as a loading control of cell lysates. B, Western blot analysis of secreted CatA protein comparing serum-free cell culture medium derived from CM and CF after 48 h. C, Western blot analysis of EC-SOD protein in isolated CMs and CFs. Collagen 1a2 (Col1a2) protein served as the fibroblast-specific control, and GAPDH served as the loading control of cell lysates. D, Western blot analysis of secreted EC-SOD protein comparing serum-free cell culture medium derived from CMs and CFs after 48 h.