EFFECTS OF LOW-MOLECULAR GTP BINDING PROTEINS AND TYROSINE KINASE ACTIVATION ON ION CHANNELS OF MYOCARDIAL CELLS.
| Project/Area Number |
01570092
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
General pharmacology
|
|---|
| Research Institution | HOKKAIDO UNIVERSITY SCHOOL OF MEDICINE |
|---|
Principal Investigator |
KANNO Morio HOKKAIDO UNIVERSITY SCHOOL OF MEDICINE, Professor, 医学部, 教授 (00109422)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOHSE Noritsugu HOKKAIDO UNIVERSITY SCHOOL OF MEDICINE, Instructor, 医学部, 助手 (80192657)
|
|---|
| Project Period (FY) |
1989 – 1990
|
| Project Status |
Completed (Fiscal Year 1990)
|
| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
|
|---|
| Keywords | Botulinum C_3 toxin / Small G protein / Tyrosin kinase / Insulin / Ion channel / Single myocardial cell / Pertussis toxin / alpha_1-adrenoceptor / ウサギ単一心筋細胞 / αー受容体 / Ito / Ik / ボツリヌス毒素 / ボツリヌスC型毒素 / 一過性外向き電流 / α-受容体 / ラット / 単一心筋細胞 |
|---|
| Research Abstract |
The aim of this research project is to determine whether low-molecular GTP binding proteins (small G protein) and activation of intracellular tyrosine kinase play crucial roles in signal transduction mechanism of cell-surface receptors.
Using a patch clamp method, we observed influences of modified small G protein by botulinum C_3 toxin and of insulin on membrane current system (I_<Na>, I_<Ca>, I_K, I_<K1> and I_<to>) of single myocardial cells obtained from rabbit hearts. In some ex13EA\ : periments, action potentials of rabbit and guinea-pig papillary muscles hearts were recorded by means of glass microelectrodes, and intracellular _pH was monitored with hydrogen-ion selective microelectrodes. The following results were obtained.
1) ADP-ribosylation of small G protein (rho protein) by botulinum C_3 toxin did not affect I_<Na>, I_<Ca>, I_K, I_<K1> and I_<to>, suggesting that rho ptotein is not an active member of signal transduction pathway controlling receptor-mediated alterat13EA\ : ions of ion-channels.
2) Insulin did not alter in any rate major membrane currents of single ventricular cells of rabbits and also did not affect Na^+/H^+ exchangers and anion transporters in guinea-pig papillary muscles. This finding implies that tyrosine kinase prese13EA\ : nt in intracellular domain of insulin receptor does not modulate ion channel functions. However, insulin did inhibit Na^+ pump current. This unexpected results warrant further study.
3) Functional inactivation of high-molecular G protein (probably G_i) induced by pertussis toxin potentiated alpha_1-adrenoceptor mediated cellular responses such as prolonged action potential duration, positive inotropic effect and hydrosis of ph13EA\ : osphatidyl inositides. This finding denies G_i as a candidate of high-molecular G protein coupling to alpha_1-adrenoceptor and suggests dynamic inhibition of G_i on intracellular signal transduction system.
|
Report
(3 results)
Research Products
(2 results)
