1990 Fiscal Year Final Research Report Summary
Calcium Transients in cut Fibers of Frog Skeletal Muscle Measured with Antipyrylazo III
| Project/Area Number |
63570069
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Neurophysiology and muscle physiology
|
|---|
| Research Institution | Kawasaki Medical School |
|---|
Principal Investigator |
MATSUMURA Moto Kawasaki Medical School, 医学部, 教授 (70052975)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
OCHI Kazunori Kawasaki Medical School, 医学部, 助手 (50069077)
|
|---|
| Project Period (FY) |
1988 – 1990
|
| Keywords | Excitation-contraction Coupling / Calcium transient / Cut fiber / Antipyrylazo III / Arsenazo III |
|---|
| Research Abstract |
The Ca transient of the cut fibers prepared from the frog skeletal muscle was investigated using Ca indicator dyes, antipyrylazo III (AP) and arsenazo III (AZ). The semitendinosus muscle fiber was held horizontally in the muscle chamber which was divided into three compartments. The preparation was mounted on the stage of the inverted microscope (TMD-2S, NIKON). AP was allowed to diffuse into the muscle fiber from the cut end immersed in one end compartment to the portion inside the middle compartment along the longitudinal direction. AZ was injected iontophoretically into the muscle fiber through the ordinary glass microelectrode. The AP-Ca transient started to rise after the latent period of 2 msec, attained the peak at 5.5 msec and then decreased exponentially with a half time of 12-16 msec (21-24^ﾟC). This wss faster than that of AZ-Ca transient. If the second stimulus was applied 10 msec after the first one, the amplitude of AP-Ca transient responding to the second stimulus was only 50%, but increased with the prolongation of the interval between two stimuli and turned back to full recovery within 60 msec. The observation of the refractory period to the second stimulus suggests that the increase of the myoplasmic Ca ion concentration inhibits the release of Ca from the sarcop sarcoplasmic reticulum. The falling phase of AP-Ca transient after a short tetanic stimulation was nearly the same as that following a single stimulus. This was different from the AZ-Ca transient, which showed the marked delay during tetanic stimulation. The difference was attributed to the different K_D values between AP and AZ. The capacity for Ca uptake of sarcoplasmic reticulum is independent either of the myoplasmic Ca concentration or of the amount of Ca stored in it.
|
