MAJOR PHYSIOLOGIC AND HISTOCHEMICAL CHARACTERISTICS OF INHERITED DYSTROPHY OF THE CHICKEN

Inbred crosses and inherited muscular dystrophy of the chicken

Inbred normal and genetically dystrophic chickens of New Hampshire and White Leghorn backgrounds, respectively, have been crossed to yield hybrids of normal and dystrophic genotypes in order to provide genetically homogeneous but heterozygous experimental animals. This study examined carcass and pectoral muscle weights, pectoral muscle fiber diameters, serum creatine kinase (CK) levels, muscle acetylcholinesterase (AChE), lactic dehydrogenase (LDH), and creatine kinase, and response to daily injections of corticosterone-21-acetate (C21A) of these hybrid chickens and their inbred parental lines. With the exception of pectoral muscle weight, dystrophic hybrids exhibited symptoms of dystrophy: high serum CK and high muscle AChE and low LDH levels. The results support the hypothesis that neither early muscle fiber hypertrophy nor atrophy is invariably associated with expression of the dystrophic gene; both are the result of secondary gene interactions. One experiment showed that muscle AChE levels decreased and LDH levels rose after C21A treatments.

In vivo proton spin-lattice relaxation times of normal and dystrophic muscles

In vivo spin-lattice relaxation times (T1) of water and lipid protons were measured in normal and dystrophic chicken pectoralis muscles at different ages. Values were obtained with a surface coil used as both a receiver and a transmitter. A 2 theta-T1-theta-Acquisition sequence was used for these measurements. Accuracy was verified with an inversion-recovery method using a slotted tube resonator as the transmitter and a surface coil as the receiver. It was observed that the T1 values of water protons in normal muscles decrease with age, the T1 values of water protons do not change with age in dystrophic muscles, and the T1 values of lipid protons increase with age in normal and dystrophic muscles. These results indicate a failure of the normal maturation of dystrophic muscles.