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EnglishThe effect of palmitoyl-CoA (PCoA) on Ca2+ fluxes in unfractionated SR, longitudinal tubules (LSR) and terminal cisternae (TC) subfractions, obtained from rabbit fast-twitch skeletal muscles, was investigated. After MgATP-dependent Ca2+ preloading, PCoA released Ca2+ from unfractionated SR and TC, but not from LSR. Both the extent and the rate of PCoA-induced Ca2+ release from TC were increased in a dose-dependent manner, the half-maximal effect being attained at [PCoA] of approximately 6 microM. Ruthenium red, a Ca2+ release channel blocker, completely inhibited PCoA-induced Ca2+ release, whereas caffeine, a Ca2+ release channel agonist, depleted TC of Ca2+ and prevented the PCoA action. Scatchard plot analysis of [3H]-ryanodine binding showed that PCoA increased the affinity without affecting Bmax. The action of PCoA was mimicked by a nonhydrolysable analog. The present results indicate that PCoA interacts and opens the Ca2+ release channel (ryanodine receptor) of TC and that the mechanism of action involves binding rather than hydrolysis.
| Titolo: | FATTY ACYL-COA ESTERS INDUCE CALCIUM-RELEASE FROM TERMINAL CISTERNAE OF SKELETAL-MUSCLE |
| Autori: | |
| Data di pubblicazione: | 1994 |
| Rivista: | |
| Abstract: | The effect of palmitoyl-CoA (PCoA) on Ca2+ fluxes in unfractionated SR, longitudinal tubules (LSR) and terminal cisternae (TC) subfractions, obtained from rabbit fast-twitch skeletal muscles, was investigated. After MgATP-dependent Ca2+ preloading, PCoA released Ca2+ from unfractionated SR and TC, but not from LSR. Both the extent and the rate of PCoA-induced Ca2+ release from TC were increased in a dose-dependent manner, the half-maximal effect being attained at [PCoA] of approximately 6 microM. Ruthenium red, a Ca2+ release channel blocker, completely inhibited PCoA-induced Ca2+ release, whereas caffeine, a Ca2+ release channel agonist, depleted TC of Ca2+ and prevented the PCoA action. Scatchard plot analysis of [3H]-ryanodine binding showed that PCoA increased the affinity without affecting Bmax. The action of PCoA was mimicked by a nonhydrolysable analog. The present results indicate that PCoA interacts and opens the Ca2+ release channel (ryanodine receptor) of TC and that the mechanism of action involves binding rather than hydrolysis. |
| Handle: | http://hdl.handle.net/11577/155276 |
| Appare nelle tipologie: | 01.01 - Articolo in rivista |
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