This study was conducted to determine whether dietary chicken-breast extract (CBEX), a rich source of histidine-containing dipeptides, could modify exerciseinduced changes in sarcoplasmic reticulum (SR) function. After 5 weeks of dietary CBEX, SR Ca2+-handling ability was examined in the vastus lateralis muscles of rats subjected to high-intensity running for 2.5 min. Dietary CBEX caused an approximately 15% and 45% increase (p < .01) in muscle carnosine and anserine concentrations, respectively. In resting muscles, depressions in SR Ca2+–ATPase activity were evoked by dietary CBEX without concomitant changes in SR Ca2+ uptake and release rates. The data confirm that high-intensity exercise depresses SR Ca2+ handling. In spite of the same run time, SR Ca2+ handling was reduced to a lesser degree in muscles of CBEX-containing-chow-fed rats than in standard-chow-fed rats (p < .05). These results suggest that dietary CBEX might attenuate deteriorations in SR Ca2+-handling ability that occur with high-intensity exercise.
Mishima is with the Preschool Education Dept., Hachinohe Junior College, Hachinohe, Japan, 031-0844. Yamada is with the Dept. of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden. Sakamoto and Sugiyama are with the Graduate School of Biosphere Science, Hiroshima University, Hiroshima, Japan, 739-8521. Matsunaga is with the Faculty of Education and Culture, Miyazaki University, Miyazaki, Japan, 889-2192. Maemura is with the Dept. of Physical Education, International Pacific University, Kannonji, Okayama, Japan, 709-0863. Shimizu, Takahata, and Morimatsu are with the R & D Center, Nippon Meat Packers, Inc., Tsukuba, Japan, 300-2646. Wada is with the Faculty of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan 739-8521.