scholarly journals Lack of direct evidence for a functional role of voltage-operated calcium channels in juxtaglomerular cells

1990 ◽  
Vol 416 (3) ◽  
pp. 281-287 ◽  
Author(s):  
Armin Kurtz ◽  
Ole Skott ◽  
Soheil Chegini ◽  
Reinhold Penner
Keyword(s):  
Calcium Channels ◽  
Functional Role ◽  
Direct Evidence ◽  
Juxtaglomerular Cells ◽  
Voltage Operated Calcium Channels

Functional role of sodium-calcium exchange in the regulation of renal vascular resistance

2001 ◽  
Vol 280 (1) ◽  
pp. F155-F161 ◽  
Author(s):  
Frank Schweda ◽  
Helga Seebauer ◽  
Bernhard K. Krämer ◽  
Armin Kurtz
Keyword(s):  
Calcium Channels ◽  
Vascular Resistance ◽  
Functional Role ◽  
Channel Blocker ◽  
Sodium Concentration ◽  
Renal Vascular Resistance ◽  
Partial Replacement ◽  
Chloride Channel Blocker ◽  
Renal Vascular

Our study aimed to assess a possible functional role of the Na+/Ca2+ exchanger in the regulation of renal vascular resistance (RVR). Therefore, we investigated the effects of an inhibition of the Na+/Ca2+ exchanger either by lowering the extracellular sodium concentration ([Na+]e) or, pharmacologically on RVR, by using isolated perfused rat kidneys. Graded decreases in [Na+]e led to dose-dependent increases in RVR to 4.3-fold (35 mM Na+). This vasoconstriction was markedly attenuated by lowering the extracellular calcium concentration, by the L-type calcium channel blocker amlodipine or by the chloride channel blocker niflumic acid. Further lowering of [Na+]e to 7 mM led to an increase in RVR to 7.5-fold. In this setting, amlodipine did not influence the magnitude but did influence the velocity of vasoconstriction. Pharmacological blockade of the Na+/Ca2+ exchanger with KB-R7943, benzamil, or nickel resulted in significant vasoconstriction (RVR 2.5-, 1.8-, and 4.2-fold of control, respectively). Our data suggest a functional role of the Na+/Ca2+ exchanger in the renal vascular bed. In conditions of partial replacement of [Na+]e, vasoconstriction is dependent on chloride and L-type calcium channels. A total replacement of [Na+]e leads to a vasoconstriction that is nearly independent of L-type calcium channels. This might be due to an active calcium transport into the cell by the Na+/Ca2+ exchanger.

scholarly journals Avoidance response to CO2 in the lateral horn

2018 ◽  
Author(s):  
Nélia Varela ◽  
Miguel Gaspar ◽  
Sophie Dias ◽  
Maria Luísa Vasconcelos
Keyword(s):  
Calcium Imaging ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Functional Role ◽  
Direct Evidence ◽  
Physiological Responses ◽  
Lateral Horn ◽  
The One ◽  
The Brain

ABSTRACTIn flies, the olfactory information is carried from the first relay in the brain, the antennal lobe, to the mushroom body (MB) and the lateral horn (LH). Olfactory associations are formed in the MB. The LH was ascribed a role in innate responses based on the stereotyped connectivity with the antennal lobe, stereotyped physiological responses to odors and MB silencing experiments. Direct evidence for the functional role of the LH is still missing. Here we investigate the behavioral role of the LH neurons directly, using the CO2 response as a paradigm. Our results show the involvement of the LH in innate responses. Specifically, we demonstrate that activity in two sets of neurons is required for the full behavioral response to CO2. Using calcium imaging we observe that the two sets of neurons respond to CO2 in different manners. Using independent manipulation and recording of the two sets of neurons we find that the one that projects to the SIP also outputs to the local neurons within the LH. The design of simultaneous output at the LH and the SIP, an output of the MB, allows for coordination between innate and learned responses.

The role of voltage-operated and non-voltage-operated calcium channels in endothelin-induced vasoconstriction of rat cerebral arteries

2014 ◽  
Vol 742 ◽  
pp. 65-73 ◽  
Author(s):  
Yohannes A. Mamo ◽  
James A. Angus ◽  
James Ziogas ◽  
Paul F. Soeding ◽  
Christine E. Wright
Keyword(s):  
Calcium Channels ◽  
Cerebral Arteries ◽  
Voltage Operated Calcium Channels

scholarly journals Direct evidence for a functional role of HLA-DRB1 and-DRB3 gene products in the recognition of Dermatophagoides spp.(house dust mite) by helper T lymphocytes

1990 ◽  
Vol 2 (9) ◽  
pp. 885-892 ◽  
Author(s):  
Robyn E. o'Hehir ◽  
Bernard Mach ◽  
Christine Berte ◽  
Roseanna Greenlaw ◽  
Jean-Marle Tiercy ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
House Dust ◽  
House Dust Mite ◽  
Functional Role ◽  
Direct Evidence ◽  
Gene Products ◽  
Helper T Lymphocytes ◽  
Dust Mite

Expression and functional role of L‐type and T‐type calcium channels in conducted calcium responses to local KCl application in rat mesenteric terminal arterioles

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Lars Jørn Jensen ◽  
Thomas Braunstein ◽  
Ryuji Inoue ◽  
Leanne Cribbs ◽  
Masahiro Oike ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Functional Role

α-MSH potentiates the responsiveness of mammotropes by increasing Ca2+ entry

1998 ◽  
Vol 274 (6) ◽  
pp. E971-E977 ◽  
Author(s):  
Lucia Nuñez ◽  
L. Stephen Frawley
Keyword(s):  
Fluorescence Microscopy ◽  
Calcium Channels ◽  
Digital Imaging ◽  
Anterior Pituitary ◽  
Plaque Assay ◽  
Pituitary Cells ◽  
Melanocyte Stimulating Hormone ◽  
Intracellular Ca ◽  
Voltage Operated Calcium Channels

It is well known that the suckling stimulus renders mammotropes considerably more responsive to prolactin (PRL)-releasing stimuli, and the neurointermediate lobe peptide α-melanocyte-stimulating hormone (α-MSH) has been proposed to play a pivotal role in this priming. The objectives of the present study were to determine whether α-MSH could act directly on pituitary cells to potentiate PRL release in response to two physiologically relevant PRL secretagogues, thyrotropin-releasing hormone (TRH) and ATP, and, if so, to identify the mechanism by which this priming phenomenon is manifested. To this end, we cultured anterior pituitary cells from lactating rats overnight and then subjected them to a reverse hemolytic plaque assay for PRL to evaluate their responses to various test agents. We found that α-MSH, which had no effect on PRL export when tested alone, augmented by more than threefold the secretory responses to TRH and ATP. Next, we utilized digital-imaging fluorescence microscopy of fura 2 to evaluate the role of intracellular Ca2+ in this process. We found that PRL export induced by pharmacological activation of L-type voltage-operated calcium channels was also potentiated by α-MSH, as was Ca2+ entry induced by TRH. Our results indicate that α-MSH acts as a mammotrope-priming agent on a subset of mammotropes by increasing Ca2+ entry induced by PRL secretagogues.

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