1. 1. The release of Ca2+ from the intracellular store site, as induced by inositol 1,4,5-trisphosphate, was studied in relation to free Ca2+ concentrations or amounts of stored Ca2+ in smooth muscle cells. 2. 2. The maximal Ca2+ release induced by inositol 1,4,5-trisphosphate was observed when the amount of Ca2+ in the store site was about 50% of the maximal capacity of the Ca2+ storage, and when the extra-vesicular free Ca2+ concentration was less than 1.5 × 10-6 M. 3. 3. The Ca2+ release induced by inositol 1,4,5-trisphosphate was accelerated by ATP and 5'-adenylylimidodiphosphate (AMPPNP), but not by ADP and AMP. 4. 4. This inositol 1,4,5-trisphosphate-induced Ca2+ release appeared to be specific for intracellular Ca2+ store sites (mainly sarcoplasmic reticulum), and this Ca2+ release was not apparent in the sarcolemmal fraction.
|Number of pages||5|
|Journal||Comparative Biochemistry and Physiology -- Part A: Physiology|
|Publication status||Published - 1985|
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