AI Article Synopsis
- Phenylephrine, at a concentration of 1-3 microM, increases cytoplasmic calcium ions in hepatocyte cultures.
- A 2-minute exposure to 2 microM phenylephrine can synchronize protein synthesis rhythms in these cells, despite the cultures initially lacking any rhythmic protein synthesis.
- The synchronization effect is disrupted by the calcium antagonist imipramine, suggesting that transient increases in calcium levels might play a key role in regulating protein synthesis in hepatocytes.
Article Abstract
Published data indicate that 1-3 microM adrenomimetic phenylephrine increases the concentration of calcium ions in the cytoplasm of cultured hepatocytes. We studied low-density cultures exhibiting no protein synthesis rhythm in the fresh medium and demonstrated that a 2 min action of 2 microM phenylephrine induces protein synthesis rhythm, i.e., synchronizes the synthesis oscillations in hepatocytes. A similar effect was observed for a selective inhibitor of the reticulum calcium pump, di-tert-butyl-benzohydroquinone, that increases the cytoplasm concentration of calcium ions by a receptor-independent mechanism. A calcium antagonist imipramine obviated the synchronization effect of phenylephrine. We propose that short-term changes in the cytoplasm concentration of calcium ions covering the whole cell population are among intracellular mechanisms of protein synthesis synchronization in hepatocytes in vitro.
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