Action of angiotensin II, 5-hydroxytryptamine and adenosine triphosphate on ionic currents in single ear artery cells of the rabbit.
Alun D. Hughes,Thomas B. Bolton +1 more
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TL;DR: The data suggest that angiotensin II, 5‐HT and ATP activate similar cationic conductances which are relatively non‐selective allowing mono‐ and divalent cations to cross the smooth muscle cell membrane and may allow the influx of calcium under physiological conditions.
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Abstract: 1. Angiotensin II, 5-hydroxytryptamine (5-HT) and adenosine triphosphate (ATP) evoked a transient inward current in isolated single car artery cells of rabbit held at -60 mV by whole cell voltage clamp in physiological saline using a KCL-containing pipette solution. Under these conditions agonist did not activate a calcium-dependent potassium current. 2. Responses to each agonist were transient and desensitized rapidly. Inward current at -60 mV holding potential was not abolished by blockade of voltage-dependent calcium channels or by buffering intracellular calcium with BAPTA, a calcium chelator, or following depletion of intracellular calcium stores with ryanodine. 3. The shape of the current-voltage relationships and the reversal potentials of the current induced by angiotensin II, 5-HT and ATP were similar under a variety of ionic conditions. Agonist-induced current was unaffected by replacing intracellular chloride with citrate ions or by replacing intracellular sodium with caesium or extracellular sodium with barium or calcium. Replacement of extracellular sodium with Tris shifted the reversal potential in all cases by around 30 mV negatively. 4. These data suggest that angiotensin II, 5-HT and ATP activate similar cationic conductances which are relatively non-selective allowing mono- and divalent cations to cross the smooth muscle cell membrane. These channels may allow the influx of calcium under physiological conditions.
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Citations
Properties of a Native Cation Channel Activated by Ca2+ Store Depletion in Vascular Smooth Muscle Cells
Elena S. Trepakova,Marion Gericke,Yoji Hirakawa,Robert M. Weisbrod,Richard A. Cohen,Victoria M. Bolotina +5 more
TL;DR: 3-pS nonselective cation channels are present and activated by TG or BAPTA-induced depletion of intracellular Ca2+ stores in intact SMC and can play an important role in regulation of vascular tone.
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Angiotensin II inhibits rat arterial KATP channels by inhibiting steady-state protein kinase A activity and activating protein kinase Ce.
TL;DR: The results indicate that KATP channels are activated by steady‐state phosphorylation by PKA at normal intracellular ATP levels, and that Ang II inhibits the channels both through activation of PKCε and inhibition of PKA.
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Angiotensin II Inhibition of ATP‐Sensitive K+ Currents in Rat Arterial Smooth Muscle Cells Through Protein Kinase C
TL;DR: The results suggest that Ang II modulates Katp channels through activation of PKC but not through inhibition of PKA, which is consistent with previous results on whole‐cell ATP‐sensitive K+currents.
91
Angiotensin II inhibits and alters kinetics of voltage-gated K(+) channels of rat arterial smooth muscle.
TL;DR: It is demonstrated that ANG II inhibits K(V) channels through both activation of PKC-epsilon and inhibition of PKA, although neither alone was effective.
81
Angiotensin II-activated protein kinase C targets caveolae to inhibit aortic ATP-sensitive potassium channels
TL;DR: It is shown that the inhibitory effect of Ang II on pinacidil-evoked whole-cell rat aortic K(ATP) currents persists in the presence of Gö6976, an inhibitor of the conventional PKC isoforms, but is abolished by intracellular dialysis of a selective PKCepsilon translocation inhibitor peptide.
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