Rat cardiac mast cell maturation and differentiation following acute ventricular volume overload

Objective: Cardiac mast cell numbers increase significantly within 12h following the creation of an aortocaval (AV) fistula in rats and play a central role in mediating adverse left ventricular remodeling. We studied whether this increase was related to maturation of resident immature mast cells. Methods: We measured percentages of immature and mature cardiac mast cells at 1, 2 and 7 days following AV-fistula or sham surgery and in non-surgical control rats using the alcian-blue safranin reaction. Results: Relative to sham-operated and control rats, there was a significant shift from immature to a greater percentage of mature cardiac mast cells at 1 day and 2 days post-fistula that returned to a normal distribution by 7 days. Conclusions: We conclude that the acute increase in mast cell density following volume overload is due to a paracrine response in the heart that stimulates the maturation and differentiation of resident immature cardiac mast cells.