Characteristics of inflammation-induced hypertrophy of rat intestinal smooth muscle cell

Inflammation of the human intestine causes thickening of the smooth muscle layers, and studies in rats infected with Trichinella spiralis (Tsp) have s hown hyperplasia of the intestinal smooth muscle cells (ISMC). We have show n that Tsp-induced inflammation caused a fivefold increase in total protein per ISMC over control, while ISMC from the noninflamed distal ileum also s howed a threefold increase. The amount of alpha-smooth muscle (SM) actin pe r ISMC increased nearly 500% over control by postinfection (PI) day 6. The proportion of alpha-SM actin in the total cellular protein increased 200% b y day 6 PI, indicating a higher density of alpha-SM actin in the hypertroph ied ISMC. gamma-SM actin mRNA increased sharply and was matched by an incre ased fractional content of gamma-SM actin protein. These increases in the s mooth muscle-specific actins may affect force production and further demons trate the plasticity of smooth muscle in the inflamed intestine.