Key result
Bradykinin or thapsigargin stimulation of cultured bovine aortic endothelial cells induces a transient hyperpolarization of approximately -20 mV followed by a sustained depolarization.
Why the study?
Does bradykinin or thapsigargin stimulation alter membrane potential in cultured bovine aortic endothelial cells?
Does bradykinin or thapsigargin stimulation alter membrane potential in cultured bovine aortic endothelial cells?
Bradykinin and thapsigargin modulate endothelial cell membrane potential through sequential activation of calcium-activated potassium channels and calcium-selective channels.
Does not support clinical application in vascular disease; leaves open translation of bovine endothelial ion dynamics to human physiology.
The present study explores the role of different ionic conductances in the regulation of membrane potential under resting conditions and after bradykinin (BK) or thapsigargin (TG) stimulation of cultured bovine aortic endothelial cells. Under resting conditions, the cell membrane potential observed was -62+/- 5 mV. The main conductance under these conditions is an inwardly rectifying potassium (IRK) channel. Application of 50 nM BK induced a transient hyperpolarization to -87 +/- 4 mV followed by sustained depolarization to -35 +/- 5 mV. The transient hyperpolarization was eliminated by 1 microM noxiustoxin, a blocker of calcium-activated postassium channels (K(Ca)). the sustained depolarization induced by BK was prevented by incubating the cells with the calcium channel blocker lanthanum. TG evoked a similar response in membrane potential, with the exception that the onset of the hyperpolarization was slower compared with BK. The results presented here indicate that the cell resting potential is maintained at -62 +/- 2 mV by the IRK channel. BK or TG stimulation induces a transient hyperpolarization of approximately -20 mV produced by activation of a KCa. This hyperpolarization is followed by a sustained depolarization produced by activation of a calcium-selective channel sensitive to lanthanum.
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Vaca et al. (1996) studied Cultured bovine aortic endothelial cells. Bradykinin (BK) or thapsigargin (TG) vs. Resting conditions was evaluated on Cell membrane potential. Bradykinin or thapsigargin stimulation of cultured bovine aortic endothelial cells induces a transient hyperpolarization of approximately -20 mV followed by a sustained depolarization.
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