Intracellular protons inhibit transient outward K+ current in ventricular myocytes from diabetic rats

The American Journal of Physiology
Z XuG J Rozanski

Abstract

This study examined the effects of protons on cardiac ion channel function in early stages of diabetes mellitus. Transient outward (I(to)) and inward rectifier K+ (IK1) currents were recorded by the whole cell, voltage-clamp technique in ventricular myocytes isolated from hearts of streptozotocin-induced diabetic and control rats. Proton concentration was controlled by independently varying the pH of buffered external or pipette (pHp) solutions. External acidification did not alter I(to) in diabetic rat myocytes when initiated after intracellular dialysis with standard pHp 7.2, but when these cells were dialyzed with acidic pHp (6.6 or 6.0), I(to) density was significantly reduced. Low pHp also reduced I(to) density more in cells from diabetic rats than in controls, whereas alkaline pHp had no effect on either group of cells compared with standard pHp 7.2. In control myocytes dialyzed with pHp 6.0, block of Na+/H+ exchange with 5-(N,N-dimethyl)-amiloride (DMA) or Na(+)-free external solution further reduced I(to) density compared with pHp 6.0 alone, whereas these treatments had less effect on acid-dialyzed cells from diabetic rats. Dialysis with pHp to 6.0 did not alter IK1 in either group of cells compared with standard pHp 7....Continue Reading

Citations

Sep 10, 2004·American Journal of Physiology. Cell Physiology·Martin BaumgartnerDiane L Barber
Nov 13, 2004·American Journal of Physiology. Heart and Circulatory Physiology·Xun LiGeorge J Rozanski
Apr 16, 2013·American Journal of Physiology. Heart and Circulatory Physiology·Noriko SaegusaKenneth W Spitzer
Feb 2, 2021·World Journal of Diabetes·Nihal OzturkSemir Ozdemir

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