scholarly journals The Role of the GX9GX3G Motif in the Gating of High Voltage-activated Ca2+Channels

2006 ◽  
Vol 281 (51) ◽  
pp. 39424-39436 ◽  
Author(s):  
Alexandra Raybaud ◽  
Yolaine Dodier ◽  
Pierre Bissonnette ◽  
Manuel Simoes ◽  
Daniel G. Bichet ◽  
...  
Keyword(s):  
High Voltage ◽  
Ca2 Channels

Role of Ca2+ channels on the hypothermic response produced by activation of κ-opioid receptors

2002 ◽  
Vol 72 (1-2) ◽  
pp. 93-99 ◽  
Author(s):  
Srinivas Gullapalli ◽  
Kumar V.S. Nemmani ◽  
Poduri Ramarao
Keyword(s):  
Opioid Receptors ◽  
Hypothermic Response ◽  
Ca2 Channels

Role of Ca2+ and Na+ on luteinizing hormone release from the calf pituitary

1988 ◽  
Vol 255 (4) ◽  
pp. E469-E474
Author(s):  
J. P. Kile ◽  
M. S. Amoss
Keyword(s):  
Luteinizing Hormone ◽  
Ionophore A23187 ◽  
Channel Blockers ◽  
Hormone Release ◽  
Primary Cells ◽  
Rat Pituitary ◽  
Voltage Dependent ◽  
Lh Release ◽  
Ca2 Channels

It has been proposed that gonadotropin-releasing hormone (GnRH) stimulates Ca2+ entry by activation of voltage-independent, receptor-mediated Ca2+ channels in the rat gonadotroph. Little work has been done on the role of calcium in GnRH-induced luteinizing hormone (LH) release in species other than the rat. Therefore, this study was done to compare the effects of agents that alter Ca2+ or Na+ entry on LH release from calf anterior pituitary primary cells in culture. GnRH (100 ng/ml), Ca2+ ionophore A23187 (2.5 microM), and the depolarizing agent ouabain (0.1-10 microM) all produced significant increases (P less than 0.05) in LH release; these effects were significantly reduced when the cells were preincubated with the organic Ca2+ channel blockers nifedipine (1-10 microM) and verapamil (1-10 microM) and with Co2+ (0.01-1 mM). The effect of ouabain was inhibited by tetrodotoxin (TTX; 1-10 nM) as well as by nifedipine at 0.1-10 microM. In contrast to its effect on rat pituitary LH release, TTX significantly inhibited GnRH-stimulated LH release at 1-100 nM. These results suggest that GnRH-induced LH release may employ Ca2+ as a second messenger in bovine gonadotrophs and support recent speculation that GnRH-induced Ca2+ mobilization may in part be voltage dependent.

scholarly journals Amphetamine-Decreased Progesterone and Estradiol Release in Rat Granulosa Cells: The Regulatory Role of cAMP- and Ca2+-Mediated Signaling Pathways

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
 Chung-Yu Chen ◽  
Chien-Rung Chen ◽  
Chiao-Nan Chen ◽  
Paulus S. Wang ◽  
Toby Mündel ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Prostaglandin F2α ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Steroidogenic Enzyme ◽  
Estradiol Secretion ◽  
Basal Release ◽  
Ca2 Channels

The purpose of this study is to evaluate the amphetamine effects on progesterone and estradiol production in rat granulosa cells and the underlying cellular regulatory mechanisms. Freshly dispersed rat granulosa cells were cultured with various test drugs in the presence of amphetamine, and the estradiol/progesterone production and the cytosolic cAMP level were measured. Additionally, the cytosolic-free Ca2+ concentrations ([Ca2+]i) were measured to examine the role of Ca2+ influx in the presence of amphetamine. Amphetamine in vitro inhibited both basal and porcine follicle-stimulating hormone-stimulated estradiol/progesterone release, and amphetamine significantly decreased steroidogenic enzyme activities. Adding 8-Bromo-cAMP did not recover the inhibitory effects of amphetamine on progesterone and estradiol release. H89 significantly decreased progesterone and estradiol basal release but failed to enhance a further amphetamine inhibitory effect. Amphetamine was capable of further suppressing the release of estradiol release under the presence of nifedipine. Pretreatment with the amphetamine for 2 h decreased the basal [Ca2+]i and prostaglandin F2α-stimulated increase of [Ca2+]i. Amphetamine inhibits progesterone and estradiol secretion in rat granulosa cells through a mechanism involving decreased PKA-downstream steroidogenic enzyme activity and L-type Ca2+ channels. Our current findings show that it is necessary to study the possibility of amphetamine perturbing reproduction in females.

scholarly journals Role of a conserved glutamine in the function of voltage-gated Ca2+ channels revealed by a mutation in human CACNA1D

2018 ◽  
Vol 293 (37) ◽  
pp. 14444-14454 ◽  
Author(s):  
Edgar Garza-Lopez ◽  
Josue A. Lopez ◽  
Jussara Hagen ◽  
Ruth Sheffer ◽  
Vardiella Meiner ◽  
...  
Keyword(s):  
Voltage Gated ◽  
Ca2 Channels

scholarly journals Intracellular pH modulates the availability of vascular L-type Ca2+ channels.

1994 ◽  
Vol 103 (4) ◽  
pp. 647-663 ◽  
Author(s):  
U Klöckner ◽  
G Isenberg
Keyword(s):  
Intracellular Ph ◽  
Single Channel ◽  
Surface Membrane ◽  
Life Time ◽  
Bicarbonate Buffer ◽  
State Changes ◽  
Channel Currents ◽  
Inside Out ◽  
Ca2 Channels

L-type Ca2+ channel currents were recorded from myocytes isolated from bovine pial and porcine coronary arteries to study the influence of changes in intracellular pH (pHi). Whole cell ICa fell when pHi was made more acidic by substituting HEPES/NaOH with CO2/bicarbonate buffer (pHo 7.4, 36 degrees C), and increased when pHi was made more alkaline by addition of 20 mM NH4Cl. Peak ICa was less pHi sensitive than late ICa (170 ms after depolarization to 0 mV). pHi-effects on single Ca2+ channel currents were studied with 110 mM BaCl2 as the charge carrier (22 degrees C, pHo 7.4). In cell-attached patches pHi was changed by extracellular NH4Cl or through the opened cell. In inside-out patches pHi was controlled through the bath. Independent of the method used the following results were obtained: (a) Single channel conductance (24 pS) and life time of the open state were not influenced by pHi (between pHi 6 and 8.4). (b) Alkaline pHi increased and acidic pHi reduced the channel availability (frequency of nonblank sweeps). (c) Alkaline pHi increased and acidic pHi reduced the frequency of late channel re-openings. The effects are discussed in terms of a deprotonation (protonation) of cytosolic binding sites that favor (prevent) the shift of the channels from a sleepy to an available state. Changes of bath pHo mimicked the pHi effects within 20 s, suggesting that protons can rapidly permeate through the surface membrane of vascular smooth muscle cells. The role of pHi in Ca2+ homeostases and vasotonus is discussed.

Bitter stimuli induce Ca2+ signaling and CCK release in enteroendocrine STC-1 cells: role of L-type voltage-sensitive Ca2+ channels

2006 ◽  
Vol 291 (4) ◽  
pp. C726-C739 ◽  
Author(s):  
Monica C. Chen ◽  
S. Vincent Wu ◽  
Joseph R. Reeve ◽  
Enrique Rozengurt
Keyword(s):  
Endocrine Cells ◽  
Bitter Taste ◽  
Dependent Manner ◽  
Gi Tract ◽  
Intracellular Ca ◽  
Α Subunits ◽  
Ca2 Channels ◽  
Cck Release

We previously demonstrated the expression of bitter taste receptors of the type 2 family (T2R) and the α-subunits of the G protein gustducin (Gαgust) in the rodent gastrointestinal (GI) tract and in GI endocrine cells. In this study, we characterized mechanisms of Ca2+ fluxes induced by two distinct T2R ligands: denatonium benzoate (DB) and phenylthiocarbamide (PTC), in mouse enteroendocrine cell line STC-1. Both DB and PTC induced a marked increase in intracellular [Ca2+] ([Ca2+]i) in a dose- and time-dependent manner. Chelating extracellular Ca2+ with EGTA blocked the increase in [Ca2+]i induced by either DB or PTC but, in contrast, did not prevent the effect induced by bombesin. Thapsigargin blocked the transient increase in [Ca2+]i induced by bombesin, but did not attenuate the [Ca2+]i increase elicited by DB or PTC. These results indicate that Ca2+ influx mediates the increase in [Ca2+]i induced by DB and PTC in STC-1 cells. Preincubation with the L-type voltage-sensitive Ca2+ channel (L-type VSCC) blockers nitrendipine or diltiazem for 30 min inhibited the increase in [Ca2+]i elicited by DB or PTC. Furthermore, exposure to the L-type VSCCs opener BAY K 8644 potentiated the increase in [Ca2+]i induced by DB and PTC. Stimulation with DB also induced a marked increase in the release of cholecystokinin from STC-1 cells, an effect also abrogated by prior exposure to EGTA or L-type VSCC blockers. Collectively, our results demonstrate that bitter tastants increase [Ca2+]i and cholecystokinin release through Ca2+ influx mediated by the opening of L-type VSCCs in enteroendocrine STC-1 cells.

L-type Ca2+ channels in fetal and adult ovine cerebral arteries

2002 ◽  
Vol 282 (1) ◽  
pp. R131-R138 ◽  
Author(s):  
Arlin B. Blood ◽  
Yu Zhao ◽  
Wen Long ◽  
Lubo Zhang ◽  
Lawrence D. Longo
Keyword(s):  
Carotid Arteries ◽  
Cerebral Arteries ◽  
Bay K 8644 ◽  
Channel Density ◽  
Immunoblotting Assay ◽  
Intracellular Ca ◽  
Common Carotid Arteries ◽  
Fetal Vessels ◽  
Ca2 Channels

Recently, we reported that, whereas in cerebral arteries of the adult a majority of norepinephrine (NE)-induced increase in intracellular Ca2+ concentration ([Ca2+]i) comes from release of the sarcoplasmic reticulum (SR) Ca2+ stores, in the fetus the SR Ca2+ stores are relatively small, and NE-induced increase in [Ca2+]i results mainly from activation of plasma membrane L-type Ca2+ channels (20). In an effort to establish further the role of L-type Ca2+ channels in the developing cerebral arteries, we tested the hypothesis that, in the fetus, increased reliance on plasmalemmal L-type Ca2+ channels is mediated, in part, by increased L-type Ca2+ channel density. We used3H-labeled (+)isopropyl-4-(2,1,3-benzoxadiazol-4-y1)-1,4-dihydro-(2,6-dimethyl-5-methoxycarbonyl)pyridine-3-carboxylate (PN200–110, isradipine) to measure L-type Ca2+ channel density (Bmax) in the cerebral arteries, common carotid artery (CCA), and descending aortae of fetal (∼140 gestation days), newborn (7–10 days), and adult sheep. In the cerebral and common carotid arteries, Bmax values (fmol/mg protein) of fetuses and newborns were significantly greater than those of adults. Western immunoblotting assay also revealed that the density of L-type Ca2+ channel protein in the cerebral arteries and CCA was about twofold greater in the fetus than the adult. Finally, compared with the adult, fetal cerebral arteries demonstrated a significantly greater maximum tension and [Ca2+]i in response to stimulation with the L-type Ca2+ channel agonist Bay K 8644. In addition, Bay K 8644-stimulated fetal vessels demonstrated a maximal tension and [Ca2+]isimilar to that observed in response to stimulation with 10−4 NE. These results support the idea that fetal cerebrovascular smooth muscle relies more on extracellular Ca2+ and L-type Ca2+ channels for contraction than does the adult and that this increased reliance is mediated, in part, by greater L-type Ca2+ channel density. This may have important implications in the regulation of cerebral blood flow in the developing organism.

Sign in / Sign up

Export Citation Format

Share Document