scholarly journals Castration Induces Down-Regulation of A-Type K+ Channel in Rat Vas Deferens Smooth Muscle

2019 ◽  
Vol 20 (17) ◽  
pp. 4073 ◽  
Author(s):  
Susumu Ohya ◽  
Katsunori Ito ◽  
Noriyuki Hatano ◽  
Akitoshi Ohno ◽  
Katsuhiko Muraki ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vas Deferens ◽  
Oral Treatment ◽  
Functional Expression ◽  
Rat Vas Deferens ◽  
K Channel ◽  
Α Subunit ◽  
K Channels ◽  
Expression Levels ◽  
Type K

A-type K+ channels contribute to regulating the propagation and frequency of action potentials in smooth muscle cells (SMCs). The present study (i) identified the molecular components of A-type K+ channels in rat vas deferens SMs (VDSMs) and (ii) showed the long-term, genomic effects of testosterone on their expression in VDSMs. Transcripts of the A-type K+ channel α subunit, Kv4.3L and its regulatory β subunits, KChIP3, NCS1, and DPP6-S were predominantly expressed in rat VDSMs over the other related subtypes (Kv4.2, KChIP1, KChIP2, KChIP4, and DPP10). A-type K+ current (IA) density in VDSM cells (VDSMCs) was decreased by castration without changes in IA kinetics, and decreased IA density was compensated for by an oral treatment with 17α-methyltestosterone (MET). Correspondingly, in the VDSMs of castrated rats, Kv4.3L and KChIP3 were down-regulated at both the transcript and protein expression levels. Changes in Kv4.3L and KChIP3 expression levels were compensated for by the treatment with MET. These results suggest that testosterone level changes in testosterone disorders and growth processes control the functional expression of A-type K+ channels in VDSMCs.

Effects of arachidonic acid on A-type potassium currents in smooth muscle cells of the guinea pig

1997 ◽  
Vol 272 (3) ◽  
pp. C860-C869 ◽  
Author(s):  
N. Nagano ◽  
Y. Imaizumi ◽  
M. Watanabe
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Vas Deferens ◽  
Muscle Cells ◽  
Atrial Myocytes ◽  
K Channels ◽  
Type K

Effects of arachidonic acid (AA) and related fatty acids on Ca2+ -independent transient (A-type) K+ current (I(A)) were examined in single myocytes of guinea pig vas deferens, ureter, and proximal colon as well as in rabbit vas deferens. The peak amplitude of I(A) was reduced by external application of AA (half-maximal inhibitory concentration = approximately 1 microM). The blocking effect was not changed significantly by indomethacin, nordihydroguaiaretic acid, guanosine 5'-O-(2-thiodiphosphate), or guanosine 5'-O-(3-thiotriphosphate). Pharmacological studies suggested that the effect of AA was not mediated by activation of protein kinases A or C or tyrosine kinase. AA (20:4) was the most potent of the four types of cis-eicosanoic acids with two to five double bonds (20:2 to 20:5) that were tested. I(A)-like current in cardiac atrial myocytes of the rabbit was not affected significantly by 30 microM AA. These results indicate that AA itself directly blocks A-type K+ channels. A relationship between stereospecific chemical structure of fatty acids and their blockade of A-type K+ channels is suggested. A-type K+ channels in smooth muscle cells can be clearly resolved from those in atrial myocytes by the responses to AA.

scholarly journals Comparison of Kv4.3L channel current expressed in HEK293 cells with A-type K+ channel current in rat vas deferens myocytes.

1999 ◽  
Vol 79 ◽  
pp. 57
Author(s):  
Takuma Oku ◽  
Susumu Ohya ◽  
Mamiko Tanaka ◽  
Minoru Watanabe ◽  
Yuji Imaizumi
Keyword(s):  
Vas Deferens ◽  
Rat Vas Deferens ◽  
Hek293 Cells ◽  
K Channel ◽  
Channel Current ◽  
Type K

scholarly journals Acute Oxygen Sensing in Heme Oxygenase-2 Null Mice

2006 ◽  
Vol 128 (4) ◽  
pp. 405-411 ◽  
Author(s):  
Patricia Ortega-Sáenz ◽  
Alberto Pascual ◽  
Raquel Gómez-Díaz ◽  
José López-Barneo
Keyword(s):  
Gene Expression ◽  
K Channel ◽  
Α Subunit ◽  
Organ Growth ◽  
K Channels ◽  
Channel Gene ◽  
Sensitive Organ ◽  
Stress Dependent ◽  
Acute Oxygen Sensing ◽  
O2 Sensing

Hemeoxygenase-2 (HO-2) is an antioxidant enzyme that can modulate recombinant maxi-K+ channels and has been proposed to be the acute O2 sensor in the carotid body (CB). We have tested the physiological contribution of this enzyme to O2 sensing using HO-2 null mice. HO-2 deficiency leads to a CB phenotype characterized by organ growth and alteration in the expression of stress-dependent genes, including the maxi-K+ channel α-subunit. However, sensitivity to hypoxia of CB is remarkably similar in HO-2 null animals and their control littermates. Moreover, the response to hypoxia in mouse and rat CB cells was maintained after blockade of maxi-K+ channels with iberiotoxin. Hypoxia responsiveness of the adrenal medulla (AM) (another acutely responding O2-sensitive organ) was also unaltered by HO-2 deficiency. Our data suggest that redox disregulation resulting from HO-2 deficiency affects maxi-K+ channel gene expression but it does not alter the intrinsic O2 sensitivity of CB or AM cells. Therefore, HO-2 is not a universally used acute O2 sensor.

Effect of NO donors on protein phosphorylation in intact vascular and nonvascular smooth muscles

2001 ◽  
Vol 280 (4) ◽  
pp. H1565-H1580 ◽  
Author(s):  
James K. Hennan ◽  
Jack Diamond
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Protein Phosphorylation ◽  
Vas Deferens ◽  
Smooth Muscles ◽  
Rat Aorta ◽  
Rat Vas Deferens ◽  
Two Dimensional Gel Electrophoresis ◽  
Relaxant Response ◽  
Underlying Mechanisms

It is generally well accepted that nitrovasodilator-induced relaxation of vascular smooth muscle involves elevation of cGMP and activation of a specific cGMP-dependent protein kinase [protein kinase G (PKG)]. However, the protein targets of PKG and the underlying mechanisms by which this kinase leads to a relaxant response have not been elucidated. Several types of smooth muscle, including rat myometrium and vas deferens, are not relaxed by sodium nitroprusside, even at concentrations that produce marked elevation of cGMP and activation of PKG. The main objective of our studies was to compare PKG-mediated protein phosphorylation in intact rat aorta, rat myometrium, and rat vas deferens using two-dimensional gel electrophoresis. In intact rat aorta, seven PKG substrates were detected during relaxation of the tissue. None of the PKG substrates identified in the rat aorta appeared to be phosphorylated in the myometrium or vas deferens after administration of various cGMP-elevating agents. Thus the failure of the rat myometrium and rat vas deferens to relax in the face of cGMP elevation and PKG activation may be due to a lack of PKG substrate phosphorylation.

Ca2+ handling properties of microsomal subfractions of rat vas deferens smooth muscle

1984 ◽  
Vol 62 (1) ◽  
pp. 76-79 ◽  
Author(s):  
A. K. Grover ◽  
C. Y. Kwan
Keyword(s):  
Smooth Muscle ◽  
Concentration Dependence ◽  
Vas Deferens ◽  
Membrane Vesicles ◽  
Rat Vas Deferens ◽  
Enzyme Marker ◽  
Isopycnic Centrifugation ◽  
Stimulation Of ◽  
Ph Profiles

The rat vas deferens smooth muscle microsomes on isopycnic centrifugation gave two fractions, namely F2 (15–30% sucrose) and F3 (30–40% sucrose), with comparable ATP-dependent azide-insensitive Ca2+-uptake capacities, although these fractions differed from each other in various enzyme marker activities. The fractions F2 and F3 also show similar pH profiles for the ATP-independent and ATP-dependent Ca2+ uptake, and similar ionized Ca2+-concentration dependence for the ATP-dependent Ca2+ uptake. However, the fractions F2 and F3 differ from each other in that: (a) F3 shows higher permeability to Ca2+, and (b) F3 shows higher stimulation of the ATP-dependent Ca2+ uptake by oxalate. The F3 fraction can also be used to obtain membrane vesicles loaded with Ca2+ oxalate in the presence of ATP. However, the yield of the Ca2+ oxalate enriched fraction is too low to permit their further characterization.

scholarly journals Regulation of smooth muscle contractility by the epithelium in rat vas deferens: role of ATP-induced release of PGE2

2008 ◽  
Vol 586 (20) ◽  
pp. 4843-4857 ◽  
Author(s):  
Ye Chun Ruan ◽  
Zhe Wang ◽  
Jian Yang Du ◽  
Wu Lin Zuo ◽  
Jing Hui Guo ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vas Deferens ◽  
Rat Vas Deferens ◽  
Muscle Contractility ◽  
Smooth Muscle Contractility

scholarly journals Neuroleptics antagonize a calcium-activated potassium channel in airway smooth muscle.

1987 ◽  
Vol 89 (2) ◽  
pp. 339-352 ◽  
Author(s):  
J D McCann ◽  
M J Welsh
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Dissociation Constants ◽  
Rank Order ◽  
K Channel ◽  
Airway Smooth Muscle Cells ◽  
Open Probability ◽  
K Channels ◽  
Channel Inhibition ◽  
Equilibrium Dissociation Constants

We examined the effect of neuroleptics on Ca-activated K channels from dog airway smooth muscle cells. Because these agents inhibit a variety of other Ca-mediated processes, it seemed possible that they might also inhibit Ca-activated K channels. In excised, inside-out patches, several neuroleptics potently and reversibly inhibited the K channel from the internal but not the external surface of the patch. Measurements of the effect on open probability and open- and closed-state durations support a simple kinetic model in which neuroleptics bind to and block the open channel. Inhibition by neuroleptics was moderately voltage dependent, with blockers less potent at hyperpolarizing voltages. The relationship between voltage and the dissociation constant for the blocker suggests that the binding site is one-third of the way across the channel's electrical field. Equilibrium dissociation constants for the drug-channel complex were: haloperidol, 1.0 +/- 0.1 microM; trifluoperazine, 1.4 +/- 0.1 microM; thioridazine, 2.4 +/- 0.1 microM; and chlorpromazine, 2.0 microM. This rank-order potency is different from their potency as calmodulin inhibitors, which suggests that neuroleptics bind to the channel rather than a calmodulin-channel complex.

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