Developmental regulation and maintenance of inwardly and outwardly rectifying K+ currents in sheep parotid cells

1994 ◽  
Vol 267 (5) ◽  
pp. G947-G953
Author(s):  
C. Hirono ◽  
M. C. Steward ◽  
N. Sangster ◽  
P. Poronnik ◽  
J. A. Young ◽  
...  
Keyword(s):  
Developmental Regulation ◽  
Secretory Cells ◽  
Parotid Glands ◽  
Parasympathetic Innervation ◽  
Hormonal Stimulation ◽  
Highly Active ◽  
Whole Cell Patch Clamp ◽  
Sheep Parotid ◽  
Spontaneous Secretion ◽  
Inwardly Rectifying

Sheep parotid secretory cells contain an inwardly rectifying K+ conductance not seen in nonruminants. The channels underlying this conductance are highly active in unstimulated cells and, in consequence, have been implicated in spontaneous secretion (secretion in the absence of neural and hormonal stimulation), an unusual phenomenon seen conspicuously in ruminant parotid glands. Since spontaneous secretion by the sheep parotid first appears after weaning, at the same time that the parasympathetic secretomotor innervation becomes functional, and since parasympathetic denervation of the adult parotid causes spontaneous secretion to abate over a period of weeks, it might be expected that the activity of the inwardly rectifying K+ conductance would be similarly related to parasympathetic innervation if it plays an important role in spontaneous secretion. To test this hypothesis, we used whole cell patch-clamp techniques to study the inwardly rectifying K+ conductance in secretory cells from the parotid glands of unweaned lambs and normal adult sheep studied 6 wk after unilateral parotid parasympathectomy. The secretory cells from unweaned lambs showed almost no inwardly rectifying current, and the cells from parasympathectomized glands in adults showed a reduced current compared with the contralateral control glands. Our results thus provide evidence that the inwardly rectifying current is somehow enabled by the development of a functional parasympathetic innervation.

Inhibition of inwardly rectifying K+ channels by cGMP in pulmonary vascular endothelial cells

2002 ◽  
Vol 283 (2) ◽  
pp. L297-L304 ◽  
Author(s):  
Larissa A. Shimoda ◽  
Laura E. Welsh ◽  
David B. Pearse
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Vascular Endothelial Cells ◽  
Cell Types ◽  
Protective Mechanism ◽  
Cell Integrity ◽  
Barrier Dysfunction ◽  
Whole Cell Patch Clamp ◽  
Inward Currents ◽  
Inwardly Rectifying

Endothelial barrier dysfunction is typically triggered by increased intracellular Ca2+concentration. Membrane-permeable analogs of guanosine 3′,5′-cyclic monophosphate (cGMP) prevent disruption of endothelial cell integrity. Because membrane potential ( E m), which influences the electrochemical gradient for Ca2+ influx, is regulated by K+ channels, we investigated the effect of 8-bromo-cGMP on E m and inwardly rectifying K+ (KIR) currents in bovine pulmonary artery and microvascular endothelial cells (BPAEC and BMVEC), using whole cell patch-clamp techniques. Both cell types exhibited inward currents at potentials negative to −50 mV that were abolished by application of 10 μM Ba2+, consistent with KIR current. Ba2+ also depolarized both cell types. 8-Bromo-cGMP (10−3 M) depolarized BPAEC and BMVEC and inhibited KIR current. Pretreatment with Rp-8-cPCT-cGMPS or KT-5823, protein kinase G (PKG) antagonists, did not prevent current inhibition by 8-bromo-cGMP. These data suggest that 8-bromo-cGMP induces depolarization in BPAEC and BMVEC due, in part, to PKG-independent inhibition of KIR current. The depolarization could be a protective mechanism that prevents endothelial cell barrier dysfunction by reducing the driving force for Ca2+ entry.

scholarly journals Decrease in an Inwardly Rectifying Potassium Conductance in Mouse Mammary Secretory Cells after Forced Weaning

PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0141131 ◽  
Author(s):  
Akihiro Kamikawa ◽  
Shota Sugimoto ◽  
Osamu Ichii ◽  
Daisuke Kondoh
Keyword(s):  
Potassium Conductance ◽  
Secretory Cells ◽  
Inwardly Rectifying

scholarly journals Persistence of the ground beetle (Coleoptera: Carabidae) microbiome to diet manipulation

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0241529
Author(s):  
Anita Silver ◽  
Sean Perez ◽  
Melanie Gee ◽  
Bethany Xu ◽  
Shreeya Garg ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Ground Beetle ◽  
Amplicon Sequencing ◽  
Carabid Beetles ◽  
Secretory Cells ◽  
Pygidial Gland ◽  
Defensive Compounds ◽  
Highly Active ◽  
16S Amplicon Sequencing ◽  
Host Diet

Host-associated microbiomes can play important roles in the ecology and evolution of their insect hosts, but bacterial diversity in many insect groups remains poorly understood. Here we examine the relationship between host environment, host traits, and microbial diversity in three species in the ground beetle family (Coleoptera: Carabidae), a group of roughly 40,000 species that synthesize a wide diversity of defensive compounds. This study used 16S amplicon sequencing to profile three species that are phylogenetically distantly related, trophically distinct, and whose defensive chemical secretions differ: Anisodactylus similis LeConte, 1851, Pterostichus serripes (LeConte, 1875), and Brachinus elongatulus Chaudoir, 1876. Wild-caught beetles were compared to individuals maintained in the lab for two weeks on carnivorous, herbivorous, or starvation diets (n = 3 beetles for each species-diet combination). Metagenomic samples from two highly active tissue types—guts, and pygidial gland secretory cells (which produce defensive compounds)—were processed and sequenced separately from those of the remaining body. Bacterial composition and diversity of these ground beetles were largely resilient to controlled changes to host diet. Different tissues within the same beetle harbor unique microbial communities, and secretory cells in particular were remarkably similar across species. We also found that these three carabid species have patterns of microbial diversity similar to those previously found in carabid beetles. These results provide a baseline for future studies of the role of microbes in the diversification of carabids.

scholarly journals CYTOLOGICAL LOCALIZATION OF NORADRENALINE, MONOAMINE OXIDASE AND ACETYLCHOLINESTERASE IN SALIVARY GLANDS OF DOG

1966 ◽  
Vol 14 (6) ◽  
pp. 483-490 ◽  
Author(s):  
MOTOHATSU FUJIWARA ◽  
CHIKAKO TANAKA ◽  
HIROSHI HIKOSAKA ◽  
TADAO OKEGAWA
Keyword(s):  
Monoamine Oxidase ◽  
Salivary Glands ◽  
Acetylcholinesterase Activity ◽  
Muscle Layer ◽  
Nerve Fibers ◽  
Autonomic Nerve ◽  
Secretory Cells ◽  
Monoamine Oxidase Activity ◽  
Parotid Glands ◽  
Cytological Localization

The cytological localization of noradrenaline, monoamine oxidase and acetylcholinesterase was examined in the salivary glands of the dog. The noradrenaline-fluorescent nerve fibers surrounded the secretory acini of the submaxillary, sublingual and parotid glands, but the density in the sublingual gland was much less than in the other two glands. Noradrenaline fluorescence was not seen in the cytoplasms of the acinar cells nor in the vicinity of the excretory ducts. Intense fluorescence was present outside the smooth muscle layer in various sized arteries. The distribution of monoamine oxidase activity was different from that of noradrenaline fluoresence. All the cells of the secretory acini and the excretory ducts were evenly stained. The distribution of fibers showing acetylcholinesterase activity was different from that of noradrenaline-fluorescent fibers only in that the former fibers were present around the excretory ducts as well. The composition of secretory cells in the submaxillary and sublingual glands is different in dogs and rats. However, the cytological localization of noradrenaline, monoamine oxidase and acetylcholinesterase activities in the salivary glands of the dog was essentially similar to those of the rat. It was concluded, therefore, that the autonomic nerve supply to the salivary glands does not correlate with the type of secretory cells.

A role for a background sodium current in spontaneous action potentials and secretion from rat lactotrophs

1996 ◽  
Vol 271 (6) ◽  
pp. C1927-C1934 ◽  
Author(s):  
S. Sankaranarayanan ◽  
S. M. Simasko
Keyword(s):  
Action Potentials ◽  
Sodium Current ◽  
Plaque Assay ◽  
Input Resistance ◽  
Cytosolic Calcium ◽  
Calcium Dependent ◽  
Whole Cell Patch Clamp ◽  
Spontaneous Action ◽  
Spontaneous Action Potentials ◽  
Spontaneous Secretion

We have used the perforated-patch variation of whole cell patch-clamp techniques, measurements of cytosolic calcium with use of fura 2, and secretion measurements with use of the reverse-hemolytic plaque assay to address the role of depolarizing background currents in maintaining spontaneous action potentials and spontaneous secretion from rat lactotrophs in primary culture. Replacement of bath sodium with tris(hydroxymethyl)aminomethane or N-methyl-D-glucamine caused a dramatic hyperpolarization of the cells, a cessation of spontaneous action potentials, and an increase in input resistance of cells. Tetrodotoxin had no effect on spontaneous action potentials, and removal of bath calcium stopped spiking but did not hyperpolarize the cells. The hyperpolarization in response to removal of bath sodium was associated with a decrease in cytosolic calcium levels. Finally, removal of bath sodium caused a decrease in spontaneous secretion of prolactin from lactotrophs. These data suggest that a background sodium current is essential to drive the membrane to threshold for firing spontaneous calcium-dependent action potentials in lactotrophs. This, in turn, results in elevated intracellular calcium, which supports spontaneous secretion of prolactin from these cells.

Differences in regulation of Ca2+-activated Cl− channels in colonic and parotid secretory cells

1998 ◽  
Vol 274 (1) ◽  
pp. C161-C166 ◽  
Author(s):  
Jorge Arreola ◽  
James E. Melvin ◽  
Ted Begenisich
Keyword(s):  
Kinase Inhibitor ◽  
Acinar Cells ◽  
Secretory Cells ◽  
Cam Kinase Ii ◽  
Cam Kinase ◽  
Parotid Glands ◽  
T84 Cells ◽  
Patch Clamp Technique ◽  
Calmodulin Binding ◽  
Parotid Acinar Cells

We investigated the regulation of Ca2+-activated Cl− channels in cells from the human colonic cell line T84 and acinar cells from rat parotid glands. The participation of multifunctional Ca2+- and calmodulin-dependent protein kinase (CaM kinase) II in the activation of these channels was studied using selective inhibitors of calmodulin and CaM kinase II. Ca2+-dependent Cl− currents were recorded using the whole cell patch-clamp technique. Direct inhibition of CaM kinase II by 40 μM peptide 281–302 or by 10 μM KN-62, another CaM kinase inhibitor, did not block the Cl− current in parotid acinar cells, whereas in T84 cells KN-62 markedly inhibited the Ca2+-dependent Cl− current. We also used the calmodulin-binding domain peptide 290–309 (0.5 μM), which competitively inhibits the activation of CaM kinase II. This peptide reduced the Cl− current in T84 cells by ∼70% but was without effect on the channels in parotid acinar cells. We conclude that the Ca2+-dependent Cl− channels in T84 cells are activated by CaM kinase II but that the channels in parotid acinar cells must be regulated by a fundamentally different Ca2+-dependent mechanism that does not utilize CaM kinase II or any calmodulin-dependent process.

scholarly journals K+ currents regulate the resting membrane potential, proliferation, and contractile responses in ventricular fibroblasts and myofibroblasts

2005 ◽  
Vol 288 (6) ◽  
pp. H2931-H2939 ◽  
Author(s):  
L. Chilton ◽  
S. Ohya ◽  
D. Freed ◽  
E. George ◽  
V. Drobic ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Reversal Potential ◽  
Mechanical Activity ◽  
Resting Membrane Potential ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent ◽  
Primary Determinant ◽  
Inwardly Rectifying ◽  
Low K ◽  
Ionic Basis

Despite the important roles played by ventricular fibroblasts and myofibroblasts in the formation and maintenance of the extracellular matrix, neither the ionic basis for membrane potential nor the effect of modulating membrane potential on function has been analyzed in detail. In this study, whole cell patch-clamp experiments were done using ventricular fibroblasts and myofibroblasts. Time- and voltage-dependent outward K+ currents were recorded at depolarized potentials, and an inwardly rectifying K+ (Kir) current was recorded near the resting membrane potential (RMP) and at more hyperpolarized potentials. The apparent reversal potential of Kir currents shifted to more positive potentials as the external K+ concentration ([K+]o) was raised, and this Kir current was blocked by 100–300 μM Ba2+. RT-PCR measurements showed that mRNA for Kir2.1 was expressed. Accordingly, we conclude that Kir current is a primary determinant of RMP in both fibroblasts and myofibroblasts. Changes in [K+]o influenced fibroblast membrane potential as well as proliferation and contractile functions. Recordings made with a voltage-sensitive dye, DiBAC3(4), showed that 1.5 mM [K+]o resulted in a hyperpolarization, whereas 20 mM [K+]o produced a depolarization. Low [K+]o (1.5 mM) enhanced myofibroblast number relative to control (5.4 mM [K+]o). In contrast, 20 mM [K+]o resulted in a significant reduction in myofibroblast number. In separate assays, 20 mM [K+]o significantly enhanced contraction of collagen I gels seeded with myofibroblasts compared with control mechanical activity in 5.4 mM [K+]o. In combination, these results show that ventricular fibroblasts and myofibroblasts express a variety of K+ channel α-subunits and demonstrate that Kir current can modulate RMP and alter essential physiological functions.

scholarly journals MORPHOLOGICAL AND CYTOCHEMICAL PROPERTIES OF THE HOLOCRINE CELLS IN THE EPIDIDYMIS OF THE MOUSE

1964 ◽  
Vol 12 (8) ◽  
pp. 628-639 ◽  
Author(s):  
JAN MARTAN ◽  
JOHN M. ALLEN
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Periodic Acid ◽  
Succinic Dehydrogenase ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Central Nucleus ◽  
Nicotinamide Adenine ◽  
Secretory Cells ◽  
Basal Cells ◽  
Periodic Acid Schiff ◽  
Highly Active

Holocrine secretory cells have been identified in the epithelium of the epididymal canal of the mouse. These cells develop from basal cells. During their differentiation they grow toward the lumen of the epididymal canal and come to form club-shaped structures with an expanded apical portion, a central nucleus and a thin stalk-like connection to the basement membrane. Mature holocrine cells are characterized by their high acid phosphatase and aliesterase activity. They also are highly active for succinic dehydrogenase, nicotinamide adenine dinucleotide diaphorase, and nicotinamide adenine dinucleotide phosphate diaphorase. Nucleoside diphosphatase, thiamine pyrophosphatase, adenosine triphosphatase, and alkaline nucleoside phosphatase are also found in these cells. These cells are also characterized by their reactivity with the Aoyama and periodic acid-Schiff reactions. They react moderately with the molybdate and Luxol Fast Blue MBS reactions for choline containing compounds. Mature holocrine cells may disintegrate in situ or may be discharged in toto into the lumen of the epididymal canal. Glycerylphosphorylcholine was identified in extracts prepared from sperm-free epididymides of mice. Glycerylphosphorylcholine reacts with Aoyama and periodic acid-Schiff reactions as do mature holocrine cells. This fact coupled with the identification of choline containing material in holocrine cells suggests that they may be one site for the formation of glycerylphosphorylcholine.

Human Adrenal Glomerulosa Cells Express K2P and GIRK Potassium Channels that are inhibited by AngII and ACTH

2021 ◽  
Author(s):  
John J. Enyeart ◽  
Judith A. Enyeart
Keyword(s):  
G Protein ◽  
Zona Glomerulosa ◽  
Time Dependent ◽  
Aldosterone Secretion ◽  
Girk Channels ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Girk Channel ◽  
Inwardly Rectifying ◽  
G Protein Coupled

In whole-cell patch clamp recordings, it was discovered that normal human adrenal zona glomerulosa (AZG) cells express members of the three major families of K+ channels. Among these are a two pore (K2P) leak-type and a G-protein-coupled, inwardly-rectifying (GIRK) channel, both inhibited by peptide hormones that stimulate aldosterone secretion. The K2P current displayed properties identifying it as TREK-1 (KCNK2). This outwardly-rectifying current was activated by arachidonic acid and inhibited by angiotensin II (AngII), adrenocorticotrophic hormone (ACTH), and forskolin. The activation and inhibition of TREK-1 was coupled to AZG cell hyperpolarization and depolarization, respectively. A second K2P channel, TASK-1 (KCNK3), was expressed at a lower density in AZG cells. Human AZG cells also express inwardly rectifying K+ current(s) (KIR) that include quasi-instantaneous and time-dependent components. This is the first report demonstrating the presence of KIR in whole cell recordings from AZG cells of any species. The time-dependent current was selectively inhibited by AngII, and ACTH, identifying it as a G protein-coupled (GIRK) channel, most likely KIR3.4 (KCNJ5). The quasi-instantaneous KIR current was not inhibited by AngII or ACTH, and may be a separate non-GIRK current. Finally, AZG cells express a voltage-gated, rapidly inactivating K+ current whose properties identified as KV1.4 (KCNA4), a conclusion confirmed by Northern blot. These findings demonstrate that human AZG cells express K2P and GIRK channels whose inhibition by AngII and ACTH are likely coupled to depolarization-dependent secretion. They further demonstrate that human AZG K+ channels differ fundamentally from the widely adopted rodent models for human aldosterone secretion.

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