scholarly journals Transmembrane Auxiliary Subunits of Voltage-dependent Ion Channels

1996 ◽  
Vol 271 (45) ◽  
pp. 27975-27978 ◽  
Author(s):  
Christina A. Gurnett ◽  
Kevin P. Campbell
Keyword(s):  
Ion Channels ◽  
Auxiliary Subunits ◽  
Voltage Dependent

Control of secretion in anterior pituitary cells--linking ion channels, messengers and exocytosis

1988 ◽  
Vol 139 (1) ◽  
pp. 287-316
Author(s):  
W. T. Mason ◽  
S. R. Rawlings ◽  
P. Cobbett ◽  
S. K. Sikdar ◽  
R. Zorec ◽  
...  
Keyword(s):  
Ion Channels ◽  
Intracellular Calcium ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Cell Types ◽  
Pituitary Cell ◽  
Pituitary Cells ◽  
Calcium Activity ◽  
Anterior Pituitary Cells ◽  
Voltage Dependent

Normal anterior pituitary cells, in their diversity and heterogeneity, provide a rich source of models for secretory function. However, until recently they have largely been neglected in favour of neoplastic, clonal tumour cell lines of pituitary origin, which have enabled a number of studies on supposedly homogeneous cell types. Because many of these lines appear to lack key peptide and neurotransmitter receptors, as well as being degranulated with accompanying abnormal levels of secretion, we have developed a range of normal primary anterior pituitary cell cultures using dispersion and enrichment techniques. By studying lactotrophs, somatotrophs and gonadotrophs we have revealed a number of possible transduction mechanisms by which receptors for hypothalamic peptides and neurotransmitters may control secretion. In particular, the transduction events controlling secretion from pituitary cells may differ fundamentally from those found in other cell types. Patch-clamp recordings in these various pituitary cell preparations have revealed substantial populations of voltage-dependent Na+, Ca2+ and K+ channels which may support action potentials in these cells. Although activation of these channels may gate Ca2+ entry to the cells under some conditions, our evidence taken with that of other laboratories suggests that peptide-receptor interactions leading to hormone secretion occur independently of significant membrane depolarization. Rather, secretion of hormone and rises in intracellular calcium measured with new probes for intracellular calcium activity, can occur in response to hypothalamic peptide activation in the absence of substantial changes in membrane potential. These changes in intracellular calcium activity almost certainly depend on both intracellular and extracellular calcium sources. In addition, strong evidence of a role for multiple intracellular receptors and modulators in the secretory event suggests we should consider the plasma membrane channels important for regulation of hormone secretion to be predominantly agonist-activated, rather than of the more conventional voltage-dependent type. Likewise, evidence from new methods for recording single ion channels suggests the existence of intracellular sites for channel modulation, implying they too may play an important role in secretory regulation. We shall consider new data and new technology which we hope will provide key answers to the many intriguing questions surrounding the control of pituitary hormone secretion. We shall highlight our work with recordings of single ion channels activated by peptides, and recent experiments using imaging of intracellular ionized free calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Proper Voltage-Dependent Ion Channel Function in Dysferlin-Deficient Cardiomyocytes

2015 ◽  
Vol 36 (3) ◽  
pp. 1049-1058 ◽  
Author(s):  
Lena Rubi ◽  
Vaibhavkumar S. Gawali ◽  
Helmut Kubista ◽  
Hannes Todt ◽  
Karlheinz Hilber ◽  
...  
Keyword(s):  
Ion Channels ◽  
Muscular Dystrophy ◽  
Ion Channel ◽  
Cardiac Electrophysiology ◽  
Cardiac Complications ◽  
Membrane Repair ◽  
Patch Clamp Technique ◽  
Cardiac Ion Channels ◽  
Ventricular Cardiomyocytes ◽  
Voltage Dependent

Background/Aims: Dysferlin plays a decisive role in calcium-dependent membrane repair in myocytes. Mutations in the encoding DYSF gene cause a number of myopathies, e.g. limb-girdle muscular dystrophy type 2B (LGMD2B). Besides skeletal muscle degenerative processes, dysferlin deficiency is also associated with cardiac complications. Thus, both LGMD2B patients and dysferlin-deficient mice develop a dilated cardiomyopathy. We and others have recently reported that dystrophin-deficient ventricular cardiomyocytes from mouse models of Duchenne muscular dystrophy show significant abnormalities in voltage-dependent ion channels, which may contribute to the pathophysiology in dystrophic cardiomyopathy. The aim of the present study was to investigate if dysferlin, like dystrophin, is a regulator of cardiac ion channels. Methods and Results: By using the whole cell patch-clamp technique, we compared the properties of voltage-dependent calcium and sodium channels, as well as action potentials in ventricular cardiomyocytes isolated from the hearts of normal and dysferlin-deficient (dysf) mice. In contrast to dystrophin deficiency, the lack of dysferlin did not impair the ion channel properties and left action potential parameters unaltered. In connection with normal ECGs in dysf mice these results suggest that dysferlin deficiency does not perturb cardiac electrophysiology. Conclusion: Our study demonstrates that dysferlin does not regulate cardiac voltage-dependent ion channels, and implies that abnormalities in cardiac ion channels are not a universal characteristic of all muscular dystrophy types.

Uterine Excitability and Ion Channels and Their Changes with Gestation and Hormonal Environment

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Susan Wray ◽  
Sarah Arrowsmith
Keyword(s):  
Ion Channels ◽  
Inward Rectifier ◽  
Cation Channels ◽  
Annual Review ◽  
Publication Date ◽  
K Channels ◽  
Voltage Gated ◽  
New Findings ◽  
Voltage Dependent ◽  
Pore Domain

We address advances in the understanding of myometrial physiology, focusing on excitation and the effects of gestation on ion channels and their relevance to labor. This review moves through pioneering studies to exciting new findings. We begin with the myometrium and its myocytes and describe how excitation might initiate and spread in this myogenic smooth muscle. We then review each of the ion channels in the myometrium: L- and T-type Ca2+ channels, KATP (Kir6) channels, voltage-dependent K channels (Kv4, Kv7, and Kv11), twin-pore domain K channels (TASK, TREK), inward rectifier Kir7.1, Ca2+-activated K+ channels with large (KCNMA1, Slo1), small (KCNN1–3), and intermediate (KCNN4) conductance, Na-activated K channels (Slo2), voltage-gated (SCN) Na+ and Na+ leak channels, nonselective (NALCN) channels, the Na K-ATPase, and hyperpolarization-activated cation channels. We finish by assessing how three key hormones— oxytocin, estrogen, and progesterone—modulate and integrate excitability throughout gestation. Expected final online publication date for the Annual Review of Physiology, Volume 83 is February 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Site-Specific Encoding of Citrulline, a Neutral Analog of Arginine, to Study the Atomic Basis for Voltage-Dependent Gating In Ion Channels

2018 ◽  
Vol 114 (3) ◽  
pp. 477a-478a
Author(s):  
Daniel T. Infield ◽  
Jason D. Galpin ◽  
Grace D. Galles ◽  
Christopher A. Ahern
Keyword(s):  
Ion Channels ◽  
Site Specific ◽  
Voltage Dependent

Bioferroelectricity in models of voltage-dependent ion channels

2000 ◽  
Vol 236 (1) ◽  
pp. 23-33 ◽  
Author(s):  
H. Richard Leuchtag
Keyword(s):  
Ion Channels ◽  
Voltage Dependent
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