Cytoplasmic Ca2+ oscillations evoked by receptor stimulation, G-protein activation, internal application of inositol trisphosphate or Ca2+: simultaneous microfluorimetry and Ca2+ dependent Cl- current recording in single pancreatic acinar cells.

Abstract

The effects of acetylcholine (ACh), cholecystokinin (CCK), internally applied GTP‐gamma‐S, inositol trisphosphate [Ins (1,4,5) P3] or Ca2+ on the cytoplasmic free Ca2+ concentration [( Ca2+]i) were assessed by simultaneous microfluorimetry (fura‐2) and measurement of the Ca2(+)‐dependent Cl‐ current (patch‐clamp whole‐cell recording) in single internally perfused mouse pancreatic acinar cells. ACh (0.1‐0.2 microM) evoked an oscillating increase in [Ca2+]i measured in the cell as a whole (microfluorimetry) which was synchronous with oscillations in the Ca2(+)‐dependent Cl‐ current reporting [Ca2+]i close to the cell membrane. In the same cells a lower ACh concentration (0.05 microM) evoked shorter repetitive Cl‐ current pulses that were not accompanied by similar spikes in the microfluorimetric recording. When cells did not respond to 0.1 microM ACh, caffeine (1 mM) added on top of the sustained ACh stimulus resulted in [Ca2+]i oscillations seen synchronously in both types of recording. CCK (10 nM) also evoked [Ca2+]i oscillations, but with much longer intervals between slightly broader Ca2+ pulses. Internal perfusion with 100 microM GTP‐gamma‐S evoked [Ca2+]i oscillations with a similar pattern. Ins (1,4,5) P3 (10 microM) evoked repetitive shortlasting spikes in [Ca2+]i that were only seen in the Cl‐ current traces, except in one small cell where these spikes were also observed synchronously in the microfluorimetric recording. Caffeine (1 mM) broadened these Ca2+ pulses. [Ca2+]i was also directly changed, bypassing the normal signalling process, by infusion of a low or high Ca2+ solution into the pipette.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of inositol 1,3,4,5-tetrakisphosphate on inositol trisphosphate-induced Ca2+ mobilization in freshly isolated and cultured mouse lacrimal acinar cells

“…The ion channels that carry these currents are both Ca# + -activated [21,22]. Whole-cell currents in exocrine acinar cells are used routinely to assess changes in cytosolic free Ca# + activity ([Ca# + ] i ), and they have been shown to reflect accurately changes in [Ca# + ] i [23]. In contrast with studies using pancreatic [23], submandibular [24] or parotid [25] acinar cells, we have been previously unable to demonstrate oscillatory changes in Ca# + -dependent currents in response to ACh in freshly isolated lacrimal acinar cells ( Figure 1A ; typical of 36 observations.)…”

The caffeine‐sensitive Ca2+ store in bovine adrenal chromaffin cells; an examination of its role in triggering secretion and Ca2+ homeostasis

“…We have previously shown that, in addition to the InsP3-sensitive store, these cells also possess a caffeinesensitive Ca 2÷ store that is diffusely distributed throughout the cell [5]. Caffeine-sensitive Ca 2÷ stores have also been identified in smooth muscle cells [6,7], sympathetic [8,9] and sensory [10] neurons, pancreatic acinar cells [17] and rat chromaffin cells [11]. The role that InsP3-insensitive stores play in Ca 2+ signalling in cells is unknown but is the subject of intense speculation (e.g.…”

“…The role that InsP3-insensitive stores play in Ca 2+ signalling in cells is unknown but is the subject of intense speculation (e.g. [8][9][10][11][12][13][14][15][16][17]). …”

Autocrine/Paracrine Function of Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) for Glucose Homeostasis in Pancreatic β-Cells and Adipocytes

“…Amylase Secretion Assay from Pancreatic Acini-Pancreatic acini were prepared as described with some modifications (27). Briefly, chopped pancreases of mice were digested with digestion buffer (KR buffer, pH 7.4, 10 unit/ml collagenase type IV (Sigma-Aldrich), 1% (w/v) BSA) and washed with KR buffer, 1% (w/v) BSA.…”