Ca2+ waves are organized among hepatocytes in the intact organ

Nathanson, Michael H.; Burgstahler, Angela D.; Mennone, Albert; Fallon, Michael B.; González, Carlos B.; Sáez, Juan C.

doi:10.1152/ajpgi.1995.269.1.g167

Cited by 73 publications

(93 citation statements)

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“…A large literature supports the idea that oscillatory changes in signaling molecules (e.g., Ca, cAMP) convey information distinct from changes in steady-state levels (Hajnóczky et al, 1995;Jafri and Keizer, 1995;Dupont et al, 2000a;Breitwieser, 2006), and that such oscillations occur across systems of coupled cells (cf., Nathanson et al, 1995;Robb-Gaspers and Thomas, 1995;D'Andrea and Vittur, 1996;Rottingen et al, 1997;Tordjmann et al, 1997;Dupont et al, 2000b,Ravier et al, 2005Haddock et al, 2006). In many cases, intercellular spread of the oscillatory signal has been shown to be dependent on junctional, as opposed to paracrine, communication.…”

Section: Signaling Consequences Of Different Molecular Permeabilitiesmentioning

confidence: 99%

Connexin channel permeability to cytoplasmic molecules

Harris¹

2007

Progress in Biophysics and Molecular Biology

414

346

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Connexin channels are known to be permeable to a variety of cytoplasmic molecules. The first observation of second messenger junctional permeability, made ∼30 years ago, sparked broad interest in gap junction channels as mediators of intercellular molecular signaling. Since then, much has been learned about the diversity of connexin channels with regard to isoform diversity, tissue and developmental distribution, modes of channel regulation, assembly and expression, biochemical modification and permeability, all of which appear to be dynamically regulated. This information has expanded the potential roles of connexin channels in development, physiology and disease, and made their elucidation much more complex -30 years ago such an orchestra of junctional dynamics was unanticipated. Only recently, however, have investigators been able to directly address, in this more complex framework, the key issue: What specific biological molecules, second messengers and others, are able to permeate the various types of connexin channels, and how well? An important related issue, given the ever-growing list of connexin-related pathologies, is how these permeabilities are altered by disease-causing connexin mutations. Together, many studies show that a variety of cytoplasmic molecules can permeate the different types of connexin channels. A few studies reveal differences in permeation by different molecules through a particular type of connexin channel, and differences in permeation by a particular molecule through different types of connexin channels. This article describes and evaluates the various methods used to obtain these data, presents an annotated compilation of the results, and discusses the findings in the context of what can be inferred about mechanism of selectivity and potential relevance to signaling. The data strongly suggest that highly specific interactions take place between connexin pores and specific biological molecular permeants, and that those interactions determine which cytoplasmic molecules can permeate and how well. At this time, the nature of those interactions is unclear. One hopes that with more detailed permeability and structural information, the specific molecular mechanisms of the selectivity can be elucidated.

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Section: Signaling Consequences Of Different Molecular Permeabilitiesmentioning

confidence: 99%

Connexin channel permeability to cytoplasmic molecules

Harris¹

2007

Progress in Biophysics and Molecular Biology

414

346

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“…In some of these cell systems, the source and potential physiologic role of extracellular ATP are unclear. ATP can be released from mouse fibroblasts (2) or rat basophilic leukemia cells (3) (6,7), and this also is thought to be due in part [Arg8]vasopressin, phenylephrine, and propidium iodide were from Sigma; fluo-3/AM was from Molecular Probes; suramin was from Biomol (Plymouth Meeting, PA); and indodicarbocyanine (Cy5) was from Biological Detection Systems (Pittsburgh). All other chemicals were of the highest quality commercially available.…”

mentioning

confidence: 99%

“…Furthermore, hepatocyte ATP receptors are sensitive to both ADP (20) and UTP (15), and bile duct cell ATP receptors are sensitive to UTP (10,11). Therefore, an alternative possibility is that ADP or UTP is the intercellular mediator of the mechanically induced (6,21), but considerably slower than the wave speed of greater than 100 ,um/sec that can be seen in isolated hepatocyte couplets (5) and intact liver (6) ATP release from cells are controversial. Hypoxia induces ATP release from intact perfused hearts (26), isolated cardiac myocytes (27), and erythrocytes (27) …”

mentioning

confidence: 99%

Isolated rat hepatocytes can signal to other hepatocytes and bile duct cells by release of nucleotides.

Schlosser

Burgstahler²,

Nathanson³

1996

Proc. Natl. Acad. Sci. U.S.A.

207

175

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Intercellular communication among certain cell types can occur via ATP secretion, which leads to stimulation of nucleotide receptors on target cells. In epithelial cells, however, intercellular communication is thought to occur instead via gap junctions. Here [Arg8]vasopressin, phenylephrine, and propidium iodide were from Sigma; fluo-3/AM was from Molecular Probes; suramin was from Biomol (Plymouth Meeting, PA); and indodicarbocyanine (Cy5) was from Biological Detection Systems (Pittsburgh). All other chemicals were of the highest quality commercially available.Preparation of Isolated Hepatocytes. Isolated rat hepatocytes were prepared in the Hepatocyte Isolation Core of the Yale Liver Center as described (5, 12). Briefly, rat livers were perfused with Hanks' A medium and then with Hanks' B medium containing 0.05% collagenase (Boehringer Mannheim) and 0.8 unit trypsin inhibitor (Sigma)/U tryptic activity.Livers were then excised, minced, and passed through serial nylon mesh filters, and the resultant cells were washed. These cells were suspended at a concentration of 7.5 x 105 cells per ml in Leibovitz L-15 medium (GIBCO) containing 10% fetal calf serum, 50 units penicillin, and 50 mg streptomycin/ml, and plated onto glass coverslips. Cells were incubated at 37°C and used 2-6 h after plating. When prepared in this fashion, "40% of isolated hepatocytes were not in contact with other hepatocytes, while '60% were in aggregates of two or more. Cell viability by trypan blue exclusion was measured 2 h after plating and exceeded 90%.Preparation of Isolated Bile Duct Units. Bile duct units, which are polarized and physiologically intact segments of bile duct epithelia, also were prepared in the Hepatocyte Isolation Core of the Yale Liver Center as described (13). After livers were perfused with Hanks' B medium as described above, the portal tissue residue was mechanically separated from parenchymal tissue first by shaking and then by forcing the tissue through a syringe to dissociate the remaining hepatocytes. The tissue was then minced in solution C, which contained a-MEM supplemented -with 0.066% collagenase, 0.033% Pronase, 0.006% DNase, 3% fetal calf serum, 0.1% bovine serum albumin, and penicillin/streptomycin at 100,000 units per 100 mg/liter. The minced tissue was then shaken at 37°C for 30 min, minced again, and sequentially filtered. Fragments remaining on the filters were digested for an additional 30 min Abbreviations: [Ca2+]i, cytosolic calcium; Cy5, indodicarbocyanine.

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“…This cellular model was used because the morphological and functional properties typical of liver tissues are preserved. Thus, vasopressin-induced calcium oscillation had been observed both on intact perfused liver (Nathanson et al 1995;Robb-Gaspers and Thomas 1995) and on hepatocyte multiplets reported by our laboratory (Combettes et al 1994;Tordjmann et al 1997Tordjmann et al ,1998. Such studies have been performed to improve our understanding of the spatiotemporal organization of the vasopressin-stimulated calcium wave.…”

mentioning

confidence: 85%

Distribution of Signaling Molecules Involved in Vasopressin-induced Ca²⁺ Mobilization in Rat Hepatocyte Multiplets

Tran

Stelly

Tordjmann

et al. 1999

J Histochem Cytochem.

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SUMMARYIn freshly isolated rat hepatocyte multiplets, Ca 2 ϩ signals in response to vasopressin are highly organized. In this study we used specific probes to visualize, by fluorescence and confocal microscopy, the main signaling molecules involved in vasopressin-mediated Ca 2 ϩ responses. V1a receptors were detected with a novel fluorescent antagonist, Rhm 8 -PVA. The G ␣q/G ␣11, PLC ␤ 3 , PIP 2 , and InsP 3 receptors were detected with specific antibodies. V1a vasopressin receptors and PIP 2 were associated with the basolateral membrane and were not detected in the bile canalicular domain. G ␣q/G ␣11, PLC ␤ 3 , and InsP 3 receptors were associated with the basolateral membrane and also with other intracellular structures. We used double labeling, Western blotting, and drugs (cytochalasin D, colchicine) known to disorganize the cytoskeleton to demonstrate the partial co-localization of G ␣q/ G ␣11 with F-actin. (J Histochem Cytochem 47:601-616, 1999)

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Ca2+ waves are organized among hepatocytes in the intact organ

Cited by 73 publications

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Connexin channel permeability to cytoplasmic molecules

Connexin channel permeability to cytoplasmic molecules

Isolated rat hepatocytes can signal to other hepatocytes and bile duct cells by release of nucleotides.

Distribution of Signaling Molecules Involved in Vasopressin-induced Ca²⁺ Mobilization in Rat Hepatocyte Multiplets

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Ca2+ waves are organized among hepatocytes in the intact organ

Cited by 73 publications

References 0 publications

Connexin channel permeability to cytoplasmic molecules

Connexin channel permeability to cytoplasmic molecules

Isolated rat hepatocytes can signal to other hepatocytes and bile duct cells by release of nucleotides.

Distribution of Signaling Molecules Involved in Vasopressin-induced Ca2+ Mobilization in Rat Hepatocyte Multiplets

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Distribution of Signaling Molecules Involved in Vasopressin-induced Ca²⁺ Mobilization in Rat Hepatocyte Multiplets