| Project/Area Number |
10470010
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General physiology
|
|---|
| Research Institution | The Jikei University School of Medicine |
|---|
Principal Investigator |
KURIHARA Satoshi Faculty of Medicine Physiology Professor, 医学部, 教授 (90057026)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
FUKUDA Norio Faculty of Medicine Physiology Research Associate, 医学部, 助手 (30301534)
|
|---|
| Project Period (FY) |
1998 – 2000
|
| Project Status |
Completed (Fiscal Year 2000)
|
| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1998: ¥2,900,000 (Direct Cost: ¥2,900,000)
|
|---|
| Keywords | cardiac muscle / troponin / Ca^<2+> / muscle length / cross-bridge / Ca affinity / Ca_<2+> |
|---|
| Research Abstract |
We investigated molecular mechanisms which regulate cardiac muscle contraction using intact and skinned preparations. We measured the Ca transients and tension using aequorin which was injected into superficial cells of ferret papillary muscles. A decrease in muscle length from Lmax to 88%Lmax transiently increased intracellular Ca concentration (extra-Ca) in accordance with tension reduction. The normalized extra-Ca to intracellular Ca concentration before length reduction was increased in the solution with low Ca concentration and was reduced at higher Ca concentrations. Bay K 8644 decreased the normalized extra-Ca. These results suggest that an increase in intracellular Ca concentration increases the number of attached cross-bridges and this increases the Ca affinity of troponin C, resulting in the small normalized extra-Ca. We also measured pCa-tension relation using Triton X-100-treated skinned preparations and observed the muscle length-dependent shift of the relation. pCa-tension relation was shifted to the left at longer muscle lengths (length effect). In the presence of higher concentrations of H ion and phosphate, Ca responsiveness was decreased but length effect was enhanced. Thus, attachment of the cross-bridges is a critical factor for length-dependent change in Ca affinity of cardiac troponin C.
|
