Physiology and Pharmacology of Gap Junctions

Spray, David C.; Bennett, Michael V. L.

doi:10.1146/annurev.ph.47.030185.001433

Cited by 438 publications

(171 citation statements)

References 48 publications

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“…Cytoplasmic pH is known to affect gj in hepatocytes and other tissues (1). cAMP derivatives might alter cytoplasmic pH either through metabolic changes or, in the case of Bt2-cAMP, by enzymatic hydrolysis of the ester.…”

Section: Resultsmentioning

confidence: 99%

“…18 and 33-37), but in only a few cases has direct phosphorylation of the channel molecule been demonstrated (33,34). Effects ofcAMP on electrical coupling between cells of a variety of tissues have been reported (1)(2)(3)(4)(5)(6)(7)(8)(9); in most cases, the onset ofthe effect is hours or many minutes after application, and in one case hours were required for an effect of cAMP-dependent protein kinase (38). An exception is the dopaminergic uncoupling in retinal horizontal cells of fish and turtle, which appears to be mediated by increase in cAMP.…”

Section: Discussionmentioning

confidence: 99%

“…As with many other channels in biological membranes, conductance is altered by certain treatments (1). Recently, cAMP has been shown to act on gap junctions in a number of systems.…”

mentioning

confidence: 99%

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cAMP increases junctional conductance and stimulates phosphorylation of the 27-kDa principal gap junction polypeptide.

Sáez

Spray²,

Nairn

et al. 1986

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

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341

145

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Membrane-permeant cAMP derivatives (dibutyryl-and 8-bromo-cAMP) increase gap-junctional conductance within minutes when applied to voltage-clamped pairs of rat hepatocytes. Glucagon also increases junctional conductances, but the response has a more rapid onset and is more rapidly reversible. The glucagon effect can be prevented by intracellular injection of the protein inhibitor of the cAMPdependent protein kinase (Walsh inhibitor), indicating that the catalytic subunit of cAMP-dependent protein kinase is directly involved. The 27-kDa miijor gap junction polypeptide is phosphorylated when liver cells dissociated into small groups are incubated with 32p. Addition of 8-bromo-cAMP to cells increases the incorporation of 32P into the 27-kDa junctional protein. Serine is the amino acid residue that is phosphorylated. When isolated liver gap junctions are incubated in the presence of catalytic subunit of the cAMP-dependent protein kinase, the 27-kDa gap junction polypeptide is phosphorylated with low stoichiometry on serine. The rapid increases in gap junctional conductance caused by agents that elevate cAMP and phosphorylation of the gap junction protein by cAMPdependent protein kinase suggest that cAMP-dependent phosphorylation of the gap junction channel modulates the conductance of liver gap junctions.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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cAMP increases junctional conductance and stimulates phosphorylation of the 27-kDa principal gap junction polypeptide.

Sáez

Spray²,

Nairn

et al. 1986

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

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341

145

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“…Such connection of the adjacent trophoblastic layers is also seen in chorioallantoic placentas of other species where multiple trophoblast layers are formed such as in the hemodichorial placenta of the rabbit and the hemotrichorial placenta of the rodents [14]. Gap junctions serve as intercytoplasmic channels for the passage of hydrophilic small molecules [15][16][17][18]. In situ hybridization histochemistry revealed that connexin 26, an isoform of gap junction protein, is expressed in the rat labyrinthine wall [19].…”

Section: Structure Of the Rat And Mouse Placentasmentioning

confidence: 99%

Ultrastructure of the Rodent Placental Labyrinth: A Site of Barrier and Transport.

1997

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Abstract. The Placenta plays a pivotal role in the maternofetal exchange of substances. In the chorioallantoic placentas of rodents, maternal and fetal bloods come close in the labyrinth. Hemotrichorial placenta is formed in most of rodents including rat, mouse, and hamster. Three trophoblast layers composed of a single cytotrophoblast layer and two syncytiotrophoblast layers and endothelium of fetal capillaries lie between maternal and fetal circulations in the labyrinthine wall. Many gap junctions are present between syncytiotrophoblast layers. The double-syncytiotrophoblast layers connected by gap junctions serve as a structural basis of the placental barrier as well as a site of specific transfer of various substances. In the guinea pig placenta, only a single syncytiotrophoblast layer is formed, thereby it is classified as a hemomonochorial placenta. Endotheliochorial placenta was reported in the kangaroo rat. The ultrastructural features of the labyrinthine wall are described and discussed in relation to specific transplacental transfer of substances, especially glucose.

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“…An increase in the FSH concentration from 0 to 5.9 pg/ml allowed the membrane potential to rise from -21.6 + 0.3 mV (n = 300) to -37.0 ± 0.2 mV (n = 310) (Petersen, 1980 ;Loewenstein, 1981 ;Poisner and Trifar6, 1985) so we measured the membrane potential of cells exposed to different uncoupling treatments (Loewenstein, 1981 (Loewenstein, 1981 (Loewenstein, 1981 ;Hertzberg, Lawrence and Gilula, 1981 ;Spray and Bennett, 1985 (Joffre et al, 1984a). The membrane potential of unstimulated cells (-25.1 ± 0.6 mV) is mainly dependent on external potassium, only slightly dependent on external sodium and not directly dependent on external calcium.…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological studies of the action of gonadotropins on Leydig and Sertoli cells from rat testis

Joffre¹,

Roche²,

Duchatelle³

1988

Reprod. Nutr. Dévelop.

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Physiology and Pharmacology of Gap Junctions

Cited by 438 publications

References 48 publications

cAMP increases junctional conductance and stimulates phosphorylation of the 27-kDa principal gap junction polypeptide.

cAMP increases junctional conductance and stimulates phosphorylation of the 27-kDa principal gap junction polypeptide.

Ultrastructure of the Rodent Placental Labyrinth: A Site of Barrier and Transport.

Electrophysiological studies of the action of gonadotropins on Leydig and Sertoli cells from rat testis

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