Intracellular uptake and α-amylase and lactate dehydrogenase releasing actions of the divalent cation ionophore A23187 in dissociated pancreatic acinar cells

Subcellular distribution of the divalent cation-sensitive probe chlorotetracycline (CTC) was observed by fluorescence microscopy in isolated pancreatic acinar cells, dissociated hepatocytes, rod photoreceptors, and erythrocytes. In each cell type, areas containing membranes fluoresced intensely while areas containing no membranes (nuclei and zymogen granules) were not fluorescent. Cell compartments packed with rough endoplasmic reticulum or Golgi vesicles (acinar cells) or plasma membrane-derived membranes (rod outer segments) exhibited a uniform fluorescence. In contrast, cell compartments having large numbers of mitochondria (hepatocytes and the rod inner segment) exhibited a punctate fluorescence. Punctate fluorescence was prominent in the perinuclear and peri-granular areas of isolated acinar cells during CTC efflux, suggesting that under these conditions mitochondrial fluorescence may account for a large portion of acinar cell fluorescence. Fluorometry of dissociated pancreatic acini, preloaded with CTC, showed that application of the mitochondrial inhibitors antimycin A, NaCN, rotenone, or C1CCP, or of the divalent cation ionophore A23187 (all agents known to release mitochondrial calcium) rapidly decreased the fluorescence of acini. In the case of mitochondrial inhibitors, this response could be elicited before but not following the loss of CTC fluorescence induced by bethanechol stimulation. Removal of extracellular Ca2+ and Mg2+ or addition of EDTA also decreased fluorescence but did not prevent secretagogues or mitochondrial inhibitors from eliciting a further response. These data suggest that bethanechol acts to decrease CTC fluorescence at the same intracellular site as do mitochondrial inhibitors. This could be due to release of calcium from either mitochondria or another organelle that requires ATP to sequester calcium.

Download Full-text

Stimulus-secretion coupling in pancreatic acinar cells: influences of external sodium and calcium on responses to cholecystokinin-pancreozymin and ionophore A23187

The Journal of Physiology ◽

10.1113/jphysiol.1977.sp011935 ◽

1977 ◽

Vol 270 (1) ◽

pp. 9-28 ◽

Cited By ~ 16

Author(s):

T. Kanno ◽

A. Saito ◽

Y. Sato

Keyword(s):

Acinar Cells ◽

Pancreatic Acinar Cells ◽

Ionophore A23187 ◽

Stimulus Secretion Coupling

Download Full-text

Effects of ions on amylase release by dissociated pancreatic acinar cells

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.231.5.1562 ◽

1976 ◽

Vol 231 (5) ◽

pp. 1562-1567 ◽

Cited By ~ 36

Author(s):

JA Williams ◽

P Cary ◽

B Moffat

Keyword(s):

Guinea Pig ◽

Calcium Ionophore ◽

Acinar Cells ◽

Calcium Ionophore A23187 ◽

Pancreatic Acinar Cells ◽

Ionophore A23187 ◽

Ion Content ◽

Bathing Medium ◽

Amylase Release ◽

Mouse Cells

Dissociated acinar cells prepared from guinea pig and mouse pancreas were intact on the basis of structure, ion content, and their ability to increase release of amylase in response to bethanechol and the calcium ionophore A23187. Guinea pig but not mouse acinar cells increased amylase release in response to caerulein. An increase in the concentration of K+ in the medium, which increases amylase release from whole pancreas, did not increase release. The effect of varying the ionic content of the medium on basal and stimulated amylase release was studied. Bethanechol and caerulein were still able to stimulate amylase release when Ca2+ was omitted from the medium, whereas stimulation induced by A23187 was abolished. Elevation of the concentration of Mg2+ did not affect basal or stimulated amylase release. Removal of Na+ from the medium initially had no effect on amylase release although bethanechol-stimulated release by mouse cells was inion of the HCO3- or Cl- content of the medium did not affect cholinergic stimulation of secretion. It is concluded that stimulated amylase release by isolated acinar cells is relatively independent of the ionic constituency of the bathing medium.

Download Full-text

Stimulation of pancreatic acinar cell growth by CCK, epidermal growth factor, and insulin in vitro

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.251.4.g487 ◽

1986 ◽

Vol 251 (4) ◽

pp. G487-G494 ◽

Cited By ~ 11

Author(s):

C. D. Logsdon

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Dna Synthesis ◽

Acinar Cell ◽

Acinar Cells ◽

Pancreatic Acinar Cell ◽

Pancreatic Acinar Cells ◽

Intracellular Camp ◽

Ionophore A23187 ◽

Epidermal Growth

Effects of regulatory molecules on growth of mouse pancreatic acinar cells in culture were examined. The cholecystokinin (CCK) analogue caerulein and cholecystokinin octapeptide (CCK-8) each led to threefold increases in incorporation of [3H]thymidine into DNA. Gastrin, which interacts weakly with the CCK receptor, stimulated DNA synthesis, but only at much higher concentrations. In contrast, other secretagogues that utilize Ca2+ as an intracellular messenger, including carbachol, bombesin, substance P, and the ionophore A23187, did not induce trophic responses. Factors that affect intracellular cAMP concentration, such as secretin, somatostatin, VIP, DBcAMP, and forskolin, did not increase DNA synthesis in cultured pancreatic cells. Insulin and epidermal growth factor induced two- and threefold increases in [3H] thymidine incorporation into DNA, respectively. The effects of insulin were mediated via insulin-like growth factor I receptors. Steroid hormones had little effect on pancreatic acinar cell DNA synthesis. The stimulatory effects of CCK, insulin, and EGF were additive. The combination of caerulein, EGF, and insulin in a hormonally defined medium led to a tenfold increase in the incorporation of [3H]thymidine into DNA. These data indicate that CCK, EGF, and insulin directly increase DNA synthesis in pancreatic acinar cells.

Download Full-text

Phorbol esters and A23187 regulate Na+-K+-pump activity in pancreatic acinar cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1987.252.4.g499 ◽

1987 ◽

Vol 252 (4) ◽

pp. G499-G505 ◽

Cited By ~ 3

Author(s):

S. R. Hootman ◽

M. E. Brown ◽

J. A. Williams

Keyword(s):

Phorbol Ester ◽

Phorbol Esters ◽

Average Rate ◽

Acinar Cells ◽

Inhibitory Effect ◽

Pancreatic Acinar Cell ◽

Pancreatic Acinar Cells ◽

Ionophore A23187 ◽

Maximal Effect ◽

Pump Activity

To clarify the subcellular mechanisms that mediate stimulation of Na+-K+-pump activity in pancreatic acinar cells by cholinergic agonists, we examined the effects of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) and the Ca2+ ionophore A23187 on [3H]ouabain binding to dispersed guinea pig pancreatic acinar cells under conditions in which binding reflects the average rate of pump cycling. The phorbol ester more than doubled Na+-K+-pump activity as did the diacylglycerol analogue, 1-oleoyl-2-acetolyl-sn-3-glycerol. A23187 increased pump activity by a maximum of 31% at 0.3 microM but was progressively inhibitory at higher concentrations. The stimulatory effects of TPA and A23187 were additive, although either secretagogue elicited a less than additive response when added together with a maximally effective concentration of the cholinergic agonist, carbachol. Removal of extracellular Ca2+ had little effect on the pump response to TPA and did not reduce the maximal effect of A23187 but abolished the inhibitory effect seen at high ionophore concentrations in Ca2+-containing medium. These results indicate that both Ca2+ and protein kinase c are involved in regulating Na+-K+-pump activity in the pancreatic acinar cell.

Download Full-text