Calcium dependent inositol trisphosphate-induced calcium release in the guinea-pig taenia caeci.
The properties of the Ca stores in the skinned fiber bundles of the guinea-pig taenia caeci were studied by a novel method to measure Ca released from the stores using a fluorescent Ca indicator, fura-2. It is found that the capacity of the Ca stores amounts some 170 mumoles/liter cell water. There are at least two Ca release mechanisms, Ca-induced Ca release (CICR) and Ca release induced by inositol-1,4,5-trisphosphate (IP3). Only about a half of the Ca is released by the Ca-induced Ca release, while IP3 releases most of the Ca. The rate of the IP3-induced Ca release is found to be strongly enhanced by submicromolar concentrations of Ca2+.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001572:Benzofurans / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002451:Cell Compartmentation / Q000187:drug effects; D016257:Fura-2; D006168:Guinea Pigs; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D007700:Kinetics; D009130:Muscle, Smooth / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013403:Sugar Phosphates / Q000494:pharmacology*
D001572:Benzofurans; D007295:Inositol Phosphates; D013403:Sugar Phosphates; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2