Inorganic Pyrophosphatase of Cardiac and Skeletal Muscle is Enhanced by Dietary Restriction in Mice During Aging

Abstract

Hydrolysis of ATP generates inorganic pyrophosphate (PPi) in the cells, extracellular matrix, cartilage and body fluids. Inorganic pyrophosphatase (iPPase) converts PPi to orthophosphate; the extra energy from this reaction can substitute for ATP-derived energy under certain conditions. We studied the activity expression of iPPase in cardiac and skeletal muscle of young and old mice subjected to short- and long-term dietary restriction. Western blot analysis using anti-iPPase and differential polymerase chain reaction using iPPase specific primers were used to ascertain iPPase level. Significant increase in both expression and activity of iPPase were observed in older mice as compared to younger ones. Twenty four hours of fasting enhanced the expression and activity of iPPase in the cardiac and skeletal muscle of both young and old mice which were abrogated upon 24 h of re-feeding them. However, both groups of mice on long-term dietary restriction (DR) showed an additive enhancement in the level of iPPase when compared with their respective age-matched controls. This might bring about metabolic reprogramming in replenishing energy scarcity of long-term dietary restricted mice.