Flow-activated Na(+)and K(+)Current in cardiac microvascular endothelial cells.
The patch-clamp technique was used to investigate the electrical response of cardiac microvascular endothelial cells to fluid stream applied through a microtube. The fluid stream induced a membrane current whose amplitude was dependent on flow rate. The I-V relationship of the flow-activated current showed a strong inward rectification and a reversal potential close to +30 mV, which gave a P(Na)/P(k)=3.47. The inward and outward components of the current nearly disappeared when extracellular Na(+)and internal K(+), respectively, were replaced by NMDG(+). Finally, the flow-activated current was fully blocked by 50 microM Gd(3+)and La(3+). These results show that cardiac microvascular endothelial cells respond to mechanical stimulation associated with flow by increasing their permeability to Na(+)and K(+). This mechanism is suggested to contribute to ionic homeostasis at high heart rates and during post-ischaemic reperfusion.
Moccia
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Department of Physiological and Pharmacological Sciences, University of Pavia, Pavia, 27100, Italy.
Villa
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Tanzi
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D000818:Animals; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism; D004558:Electric Stimulation; D004594:Electrophysiology; D004730:Endothelium, Vascular / Q000378:metabolism*; D007477:Ions; D008564:Membrane Potentials; D008833:Microcirculation / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*
D007477:Ions; D012964:Sodium; D011188:Potassium