Histochemical and biochemical characteristics of the transient hypertrophy of the denervated rat hemidiaphragm

Abstract A systematic study of the different fiber types of rat diaphragm muscle in the first 10 days after unilateral denervation showed approximately a 10% decrease in diameter of the white fibers, 25% increase in that of intermediate fibers, and 35% increase in that of red fibers together with diminished differential staining properties both for myosin ATPase and Sudan black. There was also a doubling of the amount of connective tissue. A reduction in total lipid concentration of the tissue included decreases in both triacylglycerol and phospholipid, but not cholesterol. Magnesium concentration in the tissue also declined, as did activity of Ca 2+ -activated, though not Mg 2+ -activated, myosin ATPase.