Regulatory volume decrease (RVD) is essential for the survival of animal cells. The aim of this study was to observe the RVD process in rat ventricular myocytes, and to determine if the KATP channels are involved in the RVD process in these cells. By using reverse transcriptase polymerase chain reaction and Western blot analysis, we demonstrated that there are two types of KATP channels expressed in rat ventricular myocytes: Kir6.1 and Kir6.2. When rat cardiac myocytes were exposed to hypotonic solution, cell volume increased significantly within 15 min and then gradually recovered. This typical RVD process could be inhibited by a Cl– channel blocker (0.5 mM 9-anthracene-carboxylic acid,9-AC), a K+ channel blocker (5.0 mM CsCl) and a KATP channel blocker glibenclamide (10 µM). Electrophysiological results showed that hypotonic solution activated a whole-cell current, which had similar biophysical characteristics with KATP opener (pinacidil)-induced currents. This current could be blocked by glibenclamide. Our data suggested that the RVD process in rat ventricular myocytes is dependent on the activation of K+ channels, and that KATP channels are involved in this process.
Given the potential clinical benefit of inhibiting Na+/Ca2+ exchanger (NCX) activity during myocardial ischemia reperfusion (I/R), pharmacological approaches have been pursued to both inhibit and clarify the importance of this exchanger. SEA0400 was reported to have a potent NCX selectivity. Thus, we examined the effect of SEA0400 on NCX currents and I/R induced intracellular Ca2+ overload in mouse ventricular myocytes using patch clamp techniques and fluorescence measurements. Ischemia significantly inhibited inward and outward NCX current (from -0.04±0.01nA to 0 nA at -100 mV; from 0.23±0.08 nA to 0.11±0.03 nA at +50 mV, n=7), Subsequent reperfusion not only restored the current rapidly but enhanced the current amplitude obviously, especially the outward currents (from 0.23±0.08 nA to 0.49±0.12 nA at +50 mV, n=7). [Ca2+]i, expressed as the ratio of Fura-2 fluorescence intensity, increased to 138±7 % (P<0.01) during ischemia and to 210±11 % (P<0.01) after reperfusion. The change of NCX current and the increase of [Ca2+]i during I/R can be blocked by SEA0400 in a dose-dependent manner with an EC50 value of 31 nM and 28 nM for the inward and outward NCX current, respectively. The results suggested that SEA0400 is a potent NCX inhibitor, which can protect mouse cardiac myocytes from Ca2+ overload during I/R injuries.
- MeSH
- aniliny terapeutické užití MeSH
- fenylethery terapeutické užití MeSH
- financování vládou MeSH
- ischemická choroba srdeční etiologie komplikace MeSH
- kardiomyocyty metabolismus MeSH
- metoda terčíkového zámku metody využití MeSH
- myši inbrední C57BL MeSH
- pumpa pro výměnu sodíku a vápníku antagonisté a inhibitory MeSH
- reperfuze myokardu MeSH
- Publikační typ
- srovnávací studie MeSH
