Differential beta-adrenergic regulation and phenotypic modulation of voltage-gated calcium currents in rat aortic myocytes.

We examined the dopamine (DA) modulation of calcium currents (ICa) that could contribute to the plasticity of the pyloric network in the lobster stomatogastric ganglion. Pyloric somata were voltage-clamped under conditions designed to block voltage-gated Na+, K+, and H currents. Depolarizing steps from –60 mV generated voltage-dependent, inward currents that appeared to originate in electrotonically distal, imperfectly clamped regions of the cell. These currents were blocked by Cd2+ and enhanced by Ba2+ but unaffected by Ni2+. Dopamine enhanced the peak ICa in the pyloric constrictor (PY), lateral pyloric (LP), and inferior cardiac (IC) neurons and reduced peak ICa in the ventricular dilator (VD), pyloric dilator (PD), and anterior burster (AB) neurons. All of these effects, except for the AB, are consistent with DA's excitation or inhibition of firing in the pyloric neurons. Enhancement of ICa in PY and LP neurons and reduction of ICa in VD and PD neurons are also consistent with DA-induced synaptic strength changes via modulation of presynaptic ICa. However, the reduction of ICa in AB suggests that DA's enhancement of AB transmitter release is not directly mediated through presynaptic ICa. ICa in PY and PD neurons was more sensitive to nifedipine block than in AB neurons. In addition, nifedipine blocked DA's effects on ICa in the PY and PD neurons but not in the AB neuron. Thus the contribution of specific calcium channel subtypes carrying the total ICa may vary between pyloric neuron classes, and DA may act on different calcium channel subtypes in the different pyloric neurons.

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Pertussis toxin enhances the beta-adrenergic and blocks the alpha-adrenergic regulation of renin secretion in renal cortical slices

Life Sciences ◽

10.1016/0024-3205(86)90234-1 ◽

1986 ◽

Vol 38 (11) ◽

pp. 1005-1011 ◽

Cited By ~ 5

Author(s):

José Pedraza-Chaverrí ◽

M.Carmen Alatorre-González ◽

JoséCarlos Peña ◽

J.Adolfo García-Sáinz

Keyword(s):

Pertussis Toxin ◽

Renin Secretion ◽

Beta Adrenergic ◽

Adrenergic Regulation ◽

Cortical Slices

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Calcium- and Calmodulin-Dependent Inactivation of Calcium Channels in Inner Hair Cells of the Rat Cochlea

Journal of Neurophysiology ◽

10.1152/jn.01174.2007 ◽

2008 ◽

Vol 99 (5) ◽

pp. 2183-2193 ◽

Cited By ~ 34

Author(s):

Lisa Grant ◽

Paul Fuchs

Keyword(s):

Calcium Channels ◽

Hair Cells ◽

Calcium Currents ◽

Resting Potential ◽

Resting Membrane Potential ◽

Inner Hair Cells ◽

Voltage Gated ◽

Voltage Gated Calcium Channels ◽

Dependent Inactivation ◽

Calcium Buffering

Modulation of voltage-gated calcium channels was studied in inner hair cells (IHCs) in an ex vivo preparation of the apical turn of the rat organ of Corti. Whole cell voltage clamp in the presence of potassium channel blockers showed inward calcium currents with millisecond activation and deactivation kinetics. When temperature was raised from 22 to 37°C, the calcium currents of immature IHCs [<12 days postnatal (P12)] increased threefold in amplitude, and developed more pronounced inactivation. This was determined to be calcium-dependent inactivation (CDI) on the basis of its reliance on external calcium (substitution with barium), sensitivity to internal calcium-buffering, and voltage dependence (reflecting the calcium driving force). After the onset of hearing at P12, IHC calcium current amplitude and the extent of inactivation were greatly reduced. Although smaller than in prehearing IHCs, CDI remained significant in the mature IHC near the resting membrane potential. CDI in mature IHCs was enhanced by application of the endoplasmic calcium pump blocker, benzo-hydroquinone. Conversely, CDI in immature IHCs was reduced by calmodulin inhibitors. Thus voltage-gated calcium channels in mammalian IHCs are subject to a calmodulin-mediated process of CDI. The extent of CDI depends on the balance of calcium buffering mechanisms and may be regulated by calmodulin-specific processes. CDI provides a means for the rate of spontaneous transmitter release to be adjusted to variations in hair cell resting potential and steady state calcium influx.

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beta-Adrenergic regulation of adenosine 3',5'-monophosphate concentration in brain microvessels

Science ◽

10.1126/science.34879 ◽

1979 ◽

Vol 204 (4390) ◽

pp. 330-332 ◽

Cited By ~ 102

Author(s):

T. Herbst ◽

M. Raichle ◽

J. Ferrendelli

Keyword(s):

Beta Adrenergic ◽

Adrenergic Regulation ◽

Brain Microvessels

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The Neuromuscular Junction Revisited: Ca2+ Channels and Transmitter Release in Cholinergic Neurones in Xenopus Nerve and Muscle Cell Culture

Journal of Experimental Biology ◽

10.1242/jeb.153.1.129 ◽

1990 ◽

Vol 153 (1) ◽

pp. 129-140 ◽

Cited By ~ 1

Author(s):

T. P. FENG ◽

ZHENG-SHAN DAI

Keyword(s):

Neuromuscular Junction ◽

Transmitter Release ◽

Single Channel ◽

Calcium Currents ◽

Patch Clamps ◽

Whole Cell ◽

Voltage Gated ◽

Cholinergic Neurones ◽

Ca2 Channels ◽

Evoked Transmitter Release

Although the entry of calcium ions into the presynaptic nerve terminals through voltage-gated Ca2+ channels is now universally recognized as playing an essential role in evoked transmitter release at the neuromuscular junction (NMJ), and indeed in chemical synapses generally, we have as yet very little direct knowledge of the Ca2+ channels of the presynaptic terminals. In this work, making use of cocultured nerve and muscle cells from Xenopus embryos, we studied the NMJ formed between the soma of identified cholinergic neurones and myoball, which allowed the use of patch-clamps on both the pre- and postsynaptic components. Both whole-cell and single-channel recordings of Ca2+ channels in the presynaptic cell were made. We found only one type of voltage-gated Ca2+ channel with highvoltage activation and slow inactivation characteristics, allowing its classification either as the L or the N type. The channels were susceptible to block by metenkephalin but not to block by nifedipine or to enhancement by Bay K 8644. This combination of pharmacological properties favours their classification as the N type. Preliminary observations on the correlation between calcium currents and transmitter release disclosed a strikingly rapid run-down of the evoked release with unchanged calcium currents and spontaneous release during whole-cell recording, indicating a specific wash-out effect on some link between calcium entry and evoked transmitter release.

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BETA-ADRENERGIC REGULATION OF INDOLE METABOLISM IN THE PINEAL GLAND

Frontiers in Catecholamine Research ◽

10.1016/b978-0-08-017922-3.50057-5 ◽

1973 ◽

pp. 321-325 ◽

Cited By ~ 2

Author(s):

DAVID C. KLEIN ◽

ARTHUR YUWILER

Keyword(s):

Pineal Gland ◽

Beta Adrenergic ◽

Adrenergic Regulation ◽

Indole Metabolism

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Voltage-gated currents of rabbit A- and B-type horizontal cells in retinal monolayer cultures

Visual Neuroscience ◽

10.1017/s0952523800001711 ◽

1994 ◽

Vol 11 (2) ◽

pp. 369-378 ◽

Cited By ~ 26

Author(s):

Stefan Löhrke ◽

Hans-Dieter Hofmann

Keyword(s):

Single Channel ◽

Ionic Currents ◽

Calcium Currents ◽

Horizontal Cells ◽

Delayed Rectifier ◽

Patch Clamp Recording ◽

Voltage Gated ◽

Monolayer Cultures ◽

Inward Currents

AbstractIn monolayer cultures prepared from immature early postnatal rabbit retina, small populations of neurons can be demonstrated to differentiate into apparently mature A- and B-type horizontal cells. Using wholecell, single-channel, patch-clamp recording techniques, we have analyzed the pattern of voltage-gated conductances expressed by mammalian horizontal cells under these conditions. A total of six different voltage-dependent ionic currents were recorded. Tetrodotoxin-sensitive fast sodium inward currents (INa) were found in 81% of the A-type and 90% of the B-type cells. Inward calcium currents could be demonstrated in all cells tested after blockade of other conductances. Two types of outward potassium currents with properties of the 4–aminopyridine-sensitive transient IA and the tetraethylammonium sensitive delayed rectifier IK, respectively, could be characterized in whole-cell recordings. An inward rectifying potassium current (Ianom) typical for horizontal cells was activated in response to hyperpolarizing voltage steps. These types of currents have also been described in dissociated adult horizontal cells from lower vertebrates and cat. With single-channel recordings on inside-out patches excised from B-type cells, an additional Ca2+-dependent current (IK(Ca)) was observed which, so far, has not been described in horizontal cells developing in situ. Our results demonstrate that cultured rabbit horizontal cells express a set of voltage-gated currents which largely, but not completely, corresponds to that described in situ for horizontal cells of other species. The culture system will allow further investigation of developmental and functional aspects of mammalian horizontal cells.

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