Proceedings of the National Academy of Sciences · 1985 · 417 citations · 26 references
Life SciencesCell BiologyPhysiologyCalcium HomeostasisCell SignalingSignal TransductionCalcium MetabolismCalcium SignalingCyclic Nucleotide SignalingIntracellular Calcium SignalingMuscle PhysiologyMuscle TissueCalcium Ion SignalingCalcium Signaling In Muscle CellsCalcium TransportInositol Triphosphate SignalingInositol Trisphosphate SignalingSmooth Muscle ContractionVascular Smooth Muscle Regulation
Inositol 1,4,5-trisphosphate (InsP3) caused Ca release and tension development in rabbit main pulmonary artery smooth muscle permeabilized with saponin or digitonin. Both of these responses to single additions of InsP3 (0.5-30 microM) were repeatable and occurred in the presence of 0.0-1.9 mM free Mg2+. Sustained contractions were induced by InsP3. The amount of Ca released by InsP3, measured with a Ca2+-selective electrode, was also estimated to be sufficient to stimulate contraction in intact smooth muscle. Ca release was not influenced by inhibitors of mitochondrial oxidative phosphorylation. The uptake of Ca2+ from the medium into the InsP3-sensitive pool was ATP-dependent. The present results support the hypothesis that, in smooth muscle, InsP3 is the messenger, or one of the messengers, involved in transmitter-induced (pharmacomechanical) Ca release from the sarcoplasmic reticulum, which is the intracellular Ca store identified previously as the source of Ca released by norepinephrine in main pulmonary artery.
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