Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Celia L. Carpenter is active.

Publication


Featured researches published by Celia L. Carpenter.


Brain Research | 1987

Interaction of calmodulin inhibitors and protein kinase C inhibitors with voltage-dependent calcium channels

David A. Greenberg; Celia L. Carpenter; Robert O. Messing

We compared the relative abilities of a series of calmodulin inhibitors and protein kinase C inhibitors to influence 45Ca2+ influx through voltage-dependent Ca2+ channels in PC12, a clonal neural cell line. K+-depolarization-dependent 45Ca2+ uptake was reduced by the calmodulin inhibitors calmidazolium, trifluoperazine, W-7, W-13, and W-5 at concentrations comparable to those that affect calmodulin, while the protein kinase C inhibitors polymyxin B and H-7 were weak or ineffective. The Ca2+ channel antagonist properties of calmodulin inhibitors should be considered in interpreting their effects on Ca2+-dependent cellular events.


Biochemical and Biophysical Research Communications | 1986

Inhibition of calcium flux and calcium channel antagonist binding in the PC12 neural cell line by phorbol esters and protein kinase C

Robert O. Messing; Celia L. Carpenter; David A. Greenberg

Ca2+- and phospholipid-dependent protein kinase (protein kinase C) has been shown to modify receptor-mediated Ca2+ responses in a variety of cells. To assess its possible role in modulating voltage-dependent Ca2+ responses, we examined the effect of tumor-promoting phorbol esters, which activate protein kinase C, on Ca2+ channel function in the PC12 neural cell line. Phorbol 12-myristate 13-acetate reduced K+-depolarization-evoked 45Ca uptake and decreased binding of the Ca2+ channel antagonist [3H] (+)PN200-110 to intact cells. Inhibition of binding was markedly reduced in PC12 membranes, but was restored by reconstituting membranes with protein kinase C activity. Protein kinase C may therefore participate in endogenous regulation of voltage-dependent Ca2+ channels in mammalian neural cells.


Journal of Neurochemistry | 1985

Stimulation of Calcium Uptake in PC12 Cells by the Dihydropyridine Agonist BAY K 8644

David A. Greenberg; Celia L. Carpenter; Edward C. Cooper

Abstract: Methyl 1,4‐dihydro‐2,6‐dimethyl‐3‐nitro‐4‐(2‐trifluoromethylphenyl)‐pyridine‐5‐carboxylate (BAY K 8644), an analog of dihydropyridine calcium channel antagonists, stimulated 45Ca uptake into PC12 pheochromocytoma cells. Half‐maximal stimulation occurred at 80 nM BAY K 8644. Enhancement of uptake was inhibited by cationic and organic calcium channel blockers, but not by tetrodotoxin, which is consistent with an effect on voltage‐dependent calcium channels. Stimulation of 45Ca uptake by BAY K 8644 occurred only at elevated concentrations of extracellular K+, suggesting that BAY K 8644 may interact with calcium channels in the open (activated) state.


Brain Research | 1984

Calcium channel ‘agonist’ BAY K 8644 inhibits calcium antagonist binding to brain and PC12 cell membranes

David A. Greenberg; Edward C. Cooper; Celia L. Carpenter

BAY K 8644, a drug that elicits calcium-dependent muscle contraction, inhibits binding of the voltage-dependent calcium channel antagonist [3H]nitrendipine to brain and PC12 pheochromocytoma cell membranes. This effect is due to high-affinity (Ki = 4.5 nM) competitive inhibition at the binding site for dihydropyridine calcium antagonists. Allosteric sites that mediate calcium channel blockade by non-dihydropyridine calcium antagonists are not similarly affected. Our findings indicate that BAY K 8644 is active at central, as well as peripheral, calcium channels and are compatible with a multi-state model of the voltage-dependent calcium channel in which antagonist drugs promote a closed state of the channel, while BAY K 8644 promotes an open state.


Neuroscience Letters | 1985

Inactivation of 45Ca2+ uptake by prior depolarization of PC12 cells.

David A. Greenberg; Celia L. Carpenter; Robert O. Messing

45Ca2+ uptake evoked by depolarization of PC12 pheochromocytoma cells with K+ was reduced approximately 90% by prior depolarization in Ca2+-containing medium. Prior depolarization without added Ca2+ reduced 45Ca2+ uptake by only about 20%. The Ca2+ channel agonists, BAY K 8644 and CGP 28392, had no effect on inactivation of 45Ca2+ uptake. These findings suggest that (1) voltage-gated Ca2+ channels of PC12 cells undergo inactivation, (2) inactivation is Ca2+-dependent rather than voltage-dependent, and (3) Ca2+ channel agonists do do not promote Ca2+ flux by inhibiting Ca2+ channel inactivation.


Neuroscience Letters | 1984

Calcium entry activators: distinct sites of dihydropyridine and aminopyridine action.

David A. Greenberg; Edward C. Cooper; Celia L. Carpenter

The dihydropyridine compound BAY K 8644, a putative calcium entry activator, inhibits binding of the dihydropyridine calcium entry blocker, [3H]nitrendipine, to rat skeletal muscle membranes. In contrast, aminopyridine compounds also believed to stimulate calcium flux do not interact with [3H]nitrendipine binding sites in skeletal muscle or brain. These findings suggest that calcium entry activators, like calcium entry blockers, affect voltage-dependent calcium channels by diverse mechanisms.


Journal of Neurochemistry | 1985

Reversible Dihydropyridine Isothiocyanate Binding to Brain Calcium Channels

David A. Greenberg; Edward C. Cooper; Celia L. Carpenter

Voltage‐dependent calcium channels from ileal smooth muscle can be affinity‐labeled with a [3H]dihydropyridine isothiocyanate radioligand. We examined the binding of this agent to brain membranes, to compare the properties of calcium channel drug binding sites in brain with those previously described in ileum. In brain, the [3H]dihydropyridine isothiocyanate labels sites that correspond in number and pharmacologic characteristics to binding sites for the classic calcium entry blocker, [3H]nitrendipine. However, in contrast to the covalent nature of dihydropyridine isothiocyanate binding in ileum, brain calcium channels are labeled reversibly. This difference in binding properties may reflect structural variations in voltage‐dependent calcium channels in different tissues.


Proceedings of the National Academy of Sciences of the United States of America | 1986

Ethanol regulates calcium channels in clonal neural cells

Robert O. Messing; Celia L. Carpenter; David A. Greenberg


Cancer Research | 1987

Calcium Channel Antagonist Properties of the Antineoplastic Antiestrogen Tamoxifen in the PC12 Neurosecretory Cell Line

David A. Greenberg; Celia L. Carpenter; Robert O. Messing


Journal of Pharmacology and Experimental Therapeutics | 1985

Mechanism of calcium channel inhibition by phenytoin: comparison with classical calcium channel antagonists.

Robert O. Messing; Celia L. Carpenter; David A. Greenberg

Collaboration


Dive into the Celia L. Carpenter's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar

Robert O. Messing

University of Texas at Austin

View shared research outputs
Top Co-Authors

Avatar

Edward C. Cooper

Baylor College of Medicine

View shared research outputs
Researchain Logo
Decentralizing Knowledge