Myocardial sarcomeres spontaneously oscillate with the period of heartbeat under physiological conditions.
During heartbeat, the repeated contractions of myocardium are induced by the oscillation of intracellular Ca(2+) concentration. On the other hand, when intermediately activated at a certain Ca(2+) concentration, cardiac myofibrils exhibit the spontaneous sarcomeric oscillation (Ca-SPOC) under steady ionic conditions. In the present study, we found that Ca-SPOC occurred over a wide range of Ca(2+) concentrations, including physiological contractile conditions, in skinned myocardium prepared from various animal species (rat, rabbit, pig, and cow). The period of sarcomeric oscillation fell within the same range as the period of heartbeat of each animal species. On the basis of these results we propose that the intrinsic auto-oscillatory property of sarcomeres (myofibrils) significantly contributes to myocardial beating in vivo.
Sasaki
Daisuke
D
Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Fukuda
Norio
N
Ishiwata
Shin'ichi
S
D000818:Animals; D002118:Calcium / Q000502:physiology; D002417:Cattle; D004533:Egtazic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000648:ultrastructure*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D012518:Sarcomeres / Q000502:physiology*; D013045:Species Specificity; D013552:Swine
D012433:Ryanodine; D004533:Egtazic Acid; D002118:Calcium