title: Alpha-smooth muscle actin expression in rat and mouse mesenteric wounds after transforming growth factor-beta1 treatment.
abstract: Rat mesenteric perforations heal by contraction within 5 to 7 days, whereas mouse mesenteric perforations seldom close within 3 weeks unless stimulated by transforming growth factor-beta1. In this article, we quantified the expression of alpha-smooth muscle actin by quantitative-reverse transcription-polymerase chain reaction and the orientation of actin filaments at the wound margin by Fourier transformation image analysis after treatment with transforming growth factor-beta1. The expression of transforming growth factor-beta1 and its type II receptor was also assessed. Actin filaments were shown to increase with time at the wound margin in both species and the expression of alpha-smooth muscle actin mRNA increased simultaneously. Transforming growth factor-beta1 enhanced the alpha-smooth muscle actin expression four to five times in rats and three to four times in mice on day 5, but the number of copies expressed per cell was 15-fold higher in rats than in mice. Transforming growth factor-beta1 was down-regulated after wounding in free peritoneal cells of rats, but maintained until day 5 in transforming growth factor-beta1-treated mice. The main finding of this study was that untreated, normal rats expressed substantially more alpha-smooth muscle actin than mice. After treatment with transforming growth factor-beta1, this expression increased similarly in both species. It can be hypothesized that normal closure of mesenteric perforations requires a minimum level of actin expression. This level is not reached in normal mice, but is exceeded after stimulation. Perforations in the rat always close, because the alpha-smooth muscle actin expression is always above this level.
authors.affiliation: Department of Pathology II, University Hospital, Linköping, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Ghassemifar
authors.forename: G S
authors.initials: GS
authors.lastname: Schultz
authors.forename: R W
authors.initials: RW
authors.lastname: Tarnuzzer
authors.forename: G
authors.initials: G
authors.lastname: Salerud
authors.forename: L E
authors.initials: LE
authors.lastname: Franzén