Pancreatic Secretion of Electrolytes and Water

Case, R. M.; Argent, Barry E.

doi:10.1002/cphy.cp060320

Cited by 12 publications

(26 citation statements)

References 185 publications

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“…The pancreatic acinar cells (as well as the duct cells) of mice and rats possess the cystic fibrosis transmembrane conductance regulator (CFTR) in their apical membranes and express functional CFTR-dependent chloride channels (73). In light of the above, it is noteworthy that duct cells in the rat constitute only ϳ5% of total cell volume of pancreatic tissue, whereas acinar cells account for ϳ77% of cell volume in this species (4).…”

Section: Implications Of These Studies For the Two-component Paradigmmentioning

confidence: 97%

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Yamamoto¹,

Reeve²,

Keire³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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Pancreatic secretion of protein, water, chloride, and bicarbonate under basal conditions and in response to intravenous and intraduodenal stimuli were studied in awake rats fully recovered from surgery. During the basal phase of pancreatic secretion, protein output and water output were weakly correlated or uncorrelated, consistent with separate regulation and distinct cellular origin of enzyme (acinar cells) and water (duct cells), referred to as the two-component paradigm of pancreatic secretion. When pancreatic secretion was stimulated physiologically, water and protein output abruptly became strongly and significantly correlated, suggesting that protein secretion and water secretion are tightly coupled or that protein secretion is dependent on water secretion. The apparent function of this coupling is to resist or prevent increases in protein concentration as protein output increases. This pattern of secretion was reproduced by intravenous infusion of the CCK-58 form of cholecystokinin, which strongly stimulates pancreatic water and chloride secretion, but not by CCK-8, which only weakly stimulates water and chloride secretion in a non-dose-dependent manner. The remarkably tight association of water and protein secretion in food-stimulated and CCK-58-stimulated pancreatic secretion is consistent with a single cell type as the origin of both water and enzyme secretion, i.e., the acinar cell, and is not consistent with the two-component paradigm of pancreatic secretion. Because CCK-58 is the only detectable endocrine form of cholecystokinin in the rat and its bioactivity pattern is markedly and qualitatively different from CCK-8, actions previously recorded for CCK-8 should be reexamined.

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Section: Implications Of These Studies For the Two-component Paradigmmentioning

confidence: 97%

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Yamamoto¹,

Reeve²,

Keire³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…In this respect, we have already shown that activity of the apical C1-channel can be increased by the hormone secretin, which is the physiological regulator of pancreatic bicarbonate transport [7], and also by its intracellu-lar messenger cyclic AMP [16]. Here we show that maxi-K + channels are also activated following stimulation of the duct cell and, furthermore, that channel activity remains high after patch excision.…”

Section: Introductionmentioning

confidence: 72%

“…Secretin is the physiological regulator of pancreatic bicarbonate transport and there is good evidence to suggest that this hormone uses cyclic AMP, rather than Ca 2+ as an intracellular messenger [7]. Exposing duct cells to secretin during cellattached recording markedly increased maxi-K § channel activity, and this effect was fully reversed when the hormone was washed from the tissue bath.…”

Section: Discussionmentioning

confidence: 97%

“…This paper deals with the regulation of maxi-K § channels located on the basolateral membrane of rat pancreatic duct cells [2]. These cells secrete the bicarbonate ions found in pancreatic juice, probably by an electrogenic mechanism similar to that operating in C1 -secreting epithelia [7,16,29]. As such their basolateral membrane possesses Na+/K + ATPases [28], Na+/H + exchangers [28,36], a Ba2+-sensitive K + conductance [28] and maxi-K + channels [2], while the apical membrane contains exchangers [29,36], together with a chloride conductance [29] and small conductance chloride channels [16,17].…”

Section: Introductionmentioning

confidence: 99%

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Regulation of maxi-K+ channels on pancreatic duct cells by cyclic AMP-dependent phosphorylation

Gray¹,

Greenwell²,

Garton³

et al. 1990

J. Membrain Biol.

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Using the patch-clamp technique we have identified a Ca2(+)-sensitive, voltage-dependent, maxi-K+ channel on the basolateral surface of rat pancreatic duct cells. The channel had a conductance of approximately 200 pS in excised patches bathed in symmetrical 150 mM K+, and was blocked by 1 mM Ba2+. Channel open-state probability (Po) on unstimulated cells was very low, but was markedly increased by exposing the cells to secretin, dibutyryl cyclic AMP, forskolin or isobutylmethylxanthine. Stimulation also shifted the Po/voltage relationship towards hyperpolarizing potentials, but channel conductance was unchanged. If patches were excised from stimulated cells into the inside-out configuration, Po remained high, and was not markedly reduced by lowering bath (cytoplasmic) Ca2+ concentration from 2 mM to 0.1 microM. However, activated channels were still blocked by 1 mM Ba2+. Channel Po was also increased by exposing the cytoplasmic face of excised patches to the purified catalytic subunit of cyclic AMP-dependent protein kinase. We conclude that cyclic AMP-dependent phosphorylation can activate maxi-K+ channels on pancreatic duct cells via a stable modification of the channel protein itself, or a closely associated regulatory subunit, and that phosphorylation alters the responsiveness of the channels to Ca2+. Physiologically, these K+ channels may contribute to the basolateral K+ conductance of the duct cell and, by providing a pathway for current flow across the basolateral membrane, play an important role in pancreatic bicarbonate secretion.

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“…The pancreatic duct system is known as the site of a secretin-stimulated secretion of a bicarbonate-rich fluid which solubilizes acinar enzymes and neutralizes acidic chyme in the duodenum (3). Micropuncture studies with intact gland preparations and isolated duct segments directly demonstrated the secretory ability of the interlobular ducts (10,20).…”

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confidence: 99%

The three-dimensional microanatomy of the pancreatic duct system in the Japanese monkey, Macaca fuscata, with special reference to fine proximal passages of a high species-specificity

Takahashi-Iwanaga

2013

Biomed. Res.

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We have previously shown the duct system in the rat pancreas to consist of two parts: a fine proximal (intercalated) duct and thicker distal (intralobular and interlobular) duct, with the latter part displaying morphological signs indicative of a bicarbonate-rich fluid secretion. In this study the pancreatic duct system in the Japanese monkey Macaca fuscata was observed by scanning electron microscopy after the hydrolytic exposure of cell surfaces as well as by transmission electron microscopy of ultrathin sections. Cellular expression of the water channel aquaporin 1 (AQP1) was also examined immunohistochemically. In contrast to the segmented duct system in the rat, all the duct cells in the monkey pancreas consistently displayed rich mitochondria in the cytoplasm, elaborate interdigitations of cell processes, and an intense immunoreactivity for AQP1 on the apical and basolateral cell membrane to favor active ion transport and osmotic water movement across the epithelium. Both the existence of secretory canaliculi and basal trabeculae in the duct epithelium and randomized localization of primary cilia on the luminal cell surfaces were demonstrated for the first time in monkeys, and the physiological implications of these phenomena are discussed.The pancreatic duct system is known as the site of a secretin-stimulated secretion of a bicarbonate-rich fluid which solubilizes acinar enzymes and neutralizes acidic chyme in the duodenum (3). Micropuncture studies with intact gland preparations and isolated duct segments directly demonstrated the secretory ability of the interlobular ducts (10, 20). However, the functions of smaller ducts in the pancreatic lobules remain unclear because of their inaccessibility by fine analytical techniques. By fuchsin staining of the guinea-pig pancreas, Bensley (1) reported centroacinar and intercalated duct cells in the lobules to contain considerable amounts of mitochondria that can energize active transport. His finding was subsequently corroborated in dogs and humans by transmission electron microscopy (TEM) (9,13,15). By scanning electron microscopy (SEM), Fujita et al. (5) demonstrated dense microvilli on basal surfaces of intercalated duct cells in the dog pancreas, indicating the transcellular permeation of large amounts of substances across the duct epithelium. However, our previous TEM and SEM observations have shown the rat pancreatic duct system to consist of two parts: a fine proximal (intercalated) duct which lacks morphological specialization for active transport, and a thicker distal (intralobular and interlobular) duct characterized both by the accumulation of mitochondria and elaboration of the cell membrane (21, 25). More systematical analyses are called for concerning the duct cell morphology in different animal species.Employing physiological experiments and geneexpression analyses, Ko et al. (14) identified the

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Pancreatic Secretion of Electrolytes and Water

Cited by 12 publications

References 185 publications

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Regulation of maxi-K+ channels on pancreatic duct cells by cyclic AMP-dependent phosphorylation

The three-dimensional microanatomy of the pancreatic duct system in the Japanese monkey, Macaca fuscata, with special reference to fine proximal passages of a high species-specificity

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