|
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |
|
|
|
|||||||||
|
|||||||||||
|
J Am Coll Cardiol, 2001; 38:906-915 © 2001 by the American College of Cardiology Foundation |
, MD, PhD* 
* Tayside Institute of Child Health, Ninewells Hospital & Medical School, University of Dundee, Dundee, Scotland, United Kingdom
Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Mayo Foundation, Rochester, Minnesota, USA
Manuscript received December 15, 2000; revised manuscript received May 16, 2001, accepted May 22, 2001.
Reprint requests and correspondence: Dr. Aleksandar Jovanovi, Tayside Institute of Child Health, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, United Kingdom
a.jovanovic{at}dundee.ac.uk
 |
Abstract |
|---|
 Top Abstract MethodsResultsDiscussionReferences |
|---|
The main objective of this study was to establish whether gender regulates expression and/or properties of cardiac ATP-sensitive K+ (KATP) channels.
BACKGROUND
Recently, evidence has been provided that differing cardiac responses in males and females to metabolic stress may result from gender-specific difference(s) in the efficiency of endogenous cardioprotective mechanism(s) such as KATP channels.
METHODS
A reverse transcription polymerase chain reaction (RT-PCR) using primers specific for Kir6.2, Kir6.1 and SUR2A subunits was performed on total RNA from guinea pig ventricular tissue. Western blotting using anti-Kir6.2 and anti-SUR2A antibodies was performed on cardiac membrane fraction. Whole-cell, single-channel electrophysiology and digital epifluorescent Ca2+ imaging were performed on isolated guinea pig ventricular cardiomyocytes.
RESULTS
The RT-PCR revealed higher levels of SUR2A, but not Kir6.1 and Kir6.2, messenger RNA in female tissue relative to male tissue, while much higher levels of both Kir6.2 and SUR2A proteins in cardiac membrane fraction in female tissue compared with male tissue were found. In both male and female tissue, pinacidil (100 µM), a KATP channel opener, induced outward whole-cell currents. The current density of the pinacidil-sensitive component was significantly higher in female tissue than it was in male tissue, while no differences in single KATP channel properties between genders were observed. Ischemia-reperfusion challenge induced significant intracellular Ca2+ loading in male, but not female, cardiomyocytes. To test the hypothesis that SUR2A expression is the limiting factor in KATP channel formation, we took different volumes of Kir6.2 and SUR2A complementary DNA (cDNA) from the same cDNA pool and subjected them to PCR. In order to obtain a band having 50% of the maximal intensity, a volume of SUR2a cDNA approximately 20 times the volume of Kir6.2 cDNA was required.
CONCLUSIONS
This study has demonstrated that female tissue expresses higher levels of functional cardiac KATP channels than male tissue due to the higher expression of the SUR2A subunit, which has an impact on cardiac response to ischemia-reperfusion challenge.
| ||||||||||||
It is believed that the activation of an ATP-sensitive K+ (KATP) channel is an important part of endogenous cardioprotective signaling that promotes cellular survival under conditions of severe metabolic stress (5). This ion channel was originally discovered in membrane patches excised from ventricular cardiomyocytes, and it has been hypothesized that it couples the metabolic state of the cell with membrane excitability (6). In numerous studies, it has been demonstrated that potassium channel openers—drugs that promote the opening of KATP channels—decrease infarct size, mimic ischemic preconditioning and improve functional and energetic recovery of cardiac muscle after ischemic and hypoxic insults (7). More recently, evidence has been provided to suggest that activation of sarcolemmal and mitochondrial KATP channels may promote cellular survival (7,8). The structure of mitochondrial KATP channels is still unknown, but the proteins constituting the sarcolemmal KATP channel complex have been cloned (9–12). The KATP channels are heteromultimers composed of at least two structurally distinct subunits. In heart tissue, the pore-forming inwardly-rectifying K+ channel core, Kir6.2, is primarily responsible for K+ permeance, whereas the regulatory subunit, also known as the sulfonylurea receptor or SUR2A, has been implicated in ligand-dependent channel gating (11). The established knowledge about the structure of cardiac KATP channels in the last few years permits further investigation of factors involved in the regulation of KATP channel expression and function. In this regard, we employed reverse transcription polymerase chain reaction (RT-PCR), Western blotting analysis, patch clamp electrophysiology and digital epifluorescent imaging to test the hypothesis that gender influences expression and/or properties of cardiac KATP channel.
We report that female gender is associated with higher levels of functional cardiac KATP channels, which is specifically due to the higher levels of the SUR2A subunit. We have also demonstrated that the observed gender-specific difference may have a profound impact on cardiac response to metabolic challenge.
|
Methods |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
Immunoprecipitation and Western blotting analysis. Sheep antipeptide antibodies were raised against synthetic peptides comprised of residues 33 to 47 in the Kir6.2 protein (ARFVSKKGNCNVAHK) and residues 321 to 334 in the SUR2A protein (CIVQRVNETQNGTNN), conjugated to a carrier protein, keyhole limpet hemocyanin and used for immunoprecipitation and Western blotting. To obtain the membrane cardiac fraction, guinea pig ventricular tissue was homogenized in buffer I (TRIS 10 mM, NaH2PO4 20 mM, EDTA 1 mM, PMSF 0.1 mM, pepstatin 10 µg/ml, leupeptin 10 µg/ml at pH = 7.8) and incubated for 20 min (at 4°C). The osmolarity was restored with KCl, NaCl and sucrose, and the obtained mixture was centrifugated at 500 g. The supernatant was diluted in buffer II (imidazole 30 mM, KCl 120 mM, NaCl 30 mM, NaH2PO4 20 mM, sucrose 250 mM, pepstatin 10 µg/ml, leupeptin 10 µg/ml at pH = 6.8) and centrifugated at 7,000 g; the pellet was removed, and the supernatant centrifugated at 30,000 g. The obtained pellet contained membrane fraction. Ventricular tissue was snap-frozen immediately upon extraction and ground to a powder under liquid nitrogen. The powder was resuspended in 10 ml of tissue buffer (20 mM Hepes, 150 mM NaCl, 1% Triton-X 100, pH 7.5) and homogenized. Protein concentration was determined using the method of Bradford; 10 µg of the epitope-specific Kir6.2 antibody or 40 µg of the epitope-specific SUR2A antibody was prebound to Protein-G Sepharose beads and used to immunoprecipitate from 50 µg of membrane fraction protein extract. The pellets of this precipitation were run on SDS polyacrylamide gels for Western analysis. Western blot probing was performed using 1/200 and 1/300 dilutions of anti-SUR2A and anti-Kir6.2 antibody, respectively, and detection was achieved using Protein-G HRP and ECL reagents.
Isolation of single cardiomyocytes. Ventricular cardiomyocytes were dissociated from sexually mature male and female guinea pigs (200 to 250 g) using an established enzymatic procedure (13). In brief, hearts were retrogradely perfused (at 37°C) with medium 199 for 2 to 3 min, followed by Ca2+-EGTA-buffered low-Ca2+ medium (pCa = 7) for 80 s and, finally, low-Ca2+ medium-containing pronase E (8 mg per 100 ml), proteinase K (1.7 mg per 100 ml), bovine albumin (0.1 g per 100 ml, fraction V) and 200 µM CaCl2. Ventricles were cut into small fragments (6 mm to 10 mm3) in the low-Ca2+ medium enriched with 200 µM CaCl2. Single cells were isolated by stirring the tissue (at 37°C) in a solution containing pronase E and proteinase K supplemented with collagenase (5 mg per 10 ml). After 10 min, the first aliquot was removed, filtered through a nylon sieve, centrifuged for 60 s (at 300 to 400 rpm) and washed twice. Remaining tissue fragments were re-exposed to collagenase, and isolation was continued for two to three such cycles. Isolated cardiomyocytes were stored in low-Ca2+ medium with 200 µM CaCl2. Only rod-shaped cardiomyocytes with clear striations and a smooth surface were used for electrophysiological recordings.
Whole-cell electrophysiology.
Cells were superfused with Tyrode solution (in mM: 136.5 NaCl; 5.4 KCl; 1.8 CaCl2; 0.53 MgCl2; 5.5 glucose; 5.5 HEPES-NaOH; pH 7.4). Fire-polished pipettes (resistance 3 to 5 M
) were filled with (in mM): KCl 140, MgCl2 1, ATP 3, HEPES-KOH 5 (pH 7.3). Recordings were made at room temperature (22°C). During each experiment, the membrane potential was normally held at –40 mV, and the currents were evoked by a series of 400 ms depolarizing and hyperpolarizing current steps (–80 to +80 mV in 20 mV steps) recorded directly to hard disk using an Axopatch-200B (Axon Instruments, Inc., Foster City, California) amplifier, Digidata-1321 interface and pClamp8 software. The capacitance compensation was adjusted to null the additional whole-cell capacitative current. The slow capacitance component measured by this procedure was used as an approximation of the cell surface area and allowed normalization of current amplitude (i.e., current density). The average cell capacitance was 123 ± 12 pF and 133 ± 12 pF for cardiomyocytes isolated from male and female animals, respectively (n = 8 for each). Currents were low-pass filtered at 10 kHz digitized at 2 kHz. Pooled data are presented as mean ± SEM, and values of n refer to the number of experiments in each group.
Single-channel recordings and kinetic analysis.
To monitor on-line behavior of single-channel molecules, the giagaohm seal patch-clamp technique was applied in the inside-out configuration, as we previously described (14). Cells were superfused with (in mM): KCl 140, MgCl2 1, EGTA 5, HEPES-KOH 5 (pH 7.4). Fire-polished pipettes, coated with Sylgard (resistance 5 to 7 M) were filled with (in mM): KCl 140, CaCl2 1, MgCl2 1 and HEPES-KOH 5 (pH 7.3). Recordings were made at room temperature (22°C) using a patch-clamp amplifier (Axopatch-200B). Single-channel activity was monitored on-line and stored on a PC. Data were reproduced, low-pass filtered at 1 KHz (–3 dB), sampled at 80 µs rate and further analyzed using the "pClamp8" software. The threshold for judging the open state was set at half of the single-channel amplitude. For analysis of channel behavior, amplitude and open- and closed-dwell time histograms were constructed and fitted by a single exponent.
Digital epifluorescent microscopy. Relaxed, rod-shaped, cardiomyocytes were superfused with Tyrode solution and loaded with the esterified form of the Ca2+-sensitive fluorescent probe Fura-2 (Fura-2AM, dissolved in dimethyl sulfoxide plus pluronic acid; Molecular Probes, Eugene, Oregon). Cells were imaged using a digital epifluorescence imaging system coupled with an inverted microscope (Image Solutions, Standish, United Kingdom). A mercury lamp served as a source of light to excite Fura-2AM at 340 nm and 380 nm. Fluorescence emitted at 520 nm was captured after crossing dichroic mirrors by an intensified charge coupled device camera and digitized using imaging software. An estimate of the cytosolic Ca2+ concentration, as a function of Fura-2 fluorescence, was calculated according to the equation: [Ca2+] = (R – Rmin/Rmax – R)Kdß; where R is the fluorescence ratio recorded from the cell, Rmin and Rmax the minimal and maximal fluorescence ratio, Kd the dissociation constant of the dye (236 nM) and ß the ratio of minimum to maximum fluorescence at 380 nm (15,16). The ischemia-reperfusion challenge was induced as follows: single cardiomyocytes were perfused with Tyrode solution containing (in mM) NaCl 136.5, KCl 5.4, CaCl2 1.8, MgCl2 0.53, glucose 5.5, HEPES-NaOH 5.5 (pH 7.4) at a rate of 1 ml/min. Under these conditions the PO2 in perfusate was approximately 140 mm Hg. After an initial period of equilibration, the perfusate was changed to an ischemic solution. To mimic the in vivo condition, the ischemic solution, otherwise similar to Tyrode solution, contained slightly increased K+ concentration (16 mM); pH was reduced (pH = 6.5), and glucose was omitted (17). The solution was also continuously bubbled with 100% argon, and the exchange of O2 between solution in the chamber and air was prevented by nitrogen jet (18). The PO2 under these conditions was approximately 20 mm Hg. The duration of ischemic perfusion was 20 min, followed by reperfusion with Tyrode solution for 10 min.
Statistical analysis. Data are presented as mean ± SEM, with n representing the number of patched cells or examined hearts. Mean values obtained were compared by the paired or unpaired Student t test where appropriate. Results for Kir6.2, Kir6.1 and SUR2A obtained with RT-PCR for each sample were normalized, taking into account GAPDH levels even though they were not significantly different in tested samples. The effect of gender on pinacidil-mediated protection of cardiomyocytes was assessed by the two-way repeated measures analysis of variance using the SigmaStat program (Jandel Scientific, Chicago, Illinois). A p value <0.05 was considered statistically significant.
|
Results |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
|
|
|
|
|
|
|
Discussion |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
In this study, RT-PCR analysis demonstrated higher levels of SUR2A mRNA, but not Kir6.2 mRNA and Kir6.1 mRNA, in female compared with male hearts. Although it is generally accepted that Kir6.2 and SUR2A reconstitute this cardiac KATP channel (11), we tested Kir6.1 mRNA as well, bearing in mind previous studies in which changes in Kir6.1 mRNA, but not Kir6.2 mRNA levels, were associated with the changes in SUR2A mRNA levels (21). In this study, this was not the case, and the only observed difference was at the SUR2A mRNA levels. Considering that Kir6.2 and SUR2A subunits form the KATP channel in a 1:1 ratio (19), the presence of higher levels of only one subunit does not necessarily mean that more KATP channels will be formed.
Therefore, to test the hypothesis that more KATP channels are present in the sarcolemma of female cells than male cells, we measured levels of KATP channel protein subunits in cardiac membrane fraction using Western blotting analysis. For this purpose we applied antibodies raised against epitopes on KATP channel subunits, Kir6.2 and SUR2A. Anti-Kir6.2 antibody was previously established as a specific (22), while for this study we created an anti-SUR2A antibody that has been thoroughly characterized and determined to be highly specific (Fig. 2). The Western blotting analysis of the cardiac membrane fraction demonstrated that both Kir6.2 and SUR2A subunits are present in much higher levels in cardiac membrane fraction from female tissue than from male tissue, thus providing direct evidence that density of sarcolemmal KATP channels differs between genders. Furthermore, our finding that the current density of membrane current evoked by pinacidil, a KATP channel opener, was significantly higher in female tissue than it was in male tissue is in agreement with the idea that there are more functional cardiac KATP channels in female tissue than in male tissue. The fact that that single KATP channel properties did not differ significantly between genders further confirms that the higher current density in response to pinacidil in female tissue is due to a higher number of KATP channels on the sarcolemma and not due to any gender-specific difference(s) at the level of single-channel properties. The apparent discrepancy between the results obtained with an RT-PCR methodology (differences only in SUR2A level) on one and Western blot and electrophysiology (differences in both Kir6.2 and SUR2A levels) on the other side could be explained by the fact that RT-PCR measured levels of total SUR2A and Kir6.2 mRNA, while Western blot, directly, and patch clamp electrophysiology, indirectly, selectively measured levels of those SUR2A and Kir6.2 subunits that are physically associated to form the channels.
The consequence of the gender-specific difference in cardiac KATP channel expression has yet to be fully understood. In principle, female gender is associated with a lower incidence of cardiovascular diseases (1–3), and the overexpression of Kir6.2 and SUR2A subunits confers resistance against metabolic stress in an otherwise metabolic stress-sensitive cell line (23,24). From this point of view, it is possible that more cardiac KATP channels in female tissue than in male tissue would contribute to the higher resistance of females to ischemic heart disease. For example, it has been demonstrated that cardiomyocytes isolated from female hearts are more resistant to severe metabolic stress than those from male hearts (4). In this regard, it has been shown that physiological replacement of estradiol protects the myocardium after global ischemia in the ovariectomized animals (25). In agreement with this concept, we have demonstrated here that cardiomyocytes from female cells are more resistant to ischemia-reperfusion-induced Ca2+ loading compared with cardiomyocytes from male tissue. Bearing in mind the difference between estrogen plasma levels in men and women (approximately 4 pg/ml in men vs. approximately 8 pg/ml in women [26,27]), these results are compatible with the notion that estrogens possess direct cardioprotective properties and associate expression of KATP channels with the estrogen levels.
In this study, RT-PCR analysis did not show differences in Kir6.2 levels between genders, suggesting that a higher number of KATP channels on sarcolemma are due solely to a difference in SUR2A expression. The presence of more KATP channels as a consequence of more SUR2A subunits is possible only when the levels of SUR2A in cardiomyocytes are considerably lower then the levels of Kir6.2, that is, a subunit that is less expressed in cardiac tissue controls the number of functional channel proteins. To test the possibility that Kir6.2 is present in higher amounts than SUR2A, we compared RT-PCR products using the primers for Kir6.2 and SUR2A and different amounts of cDNA. Because the PCR reaction was performed under the best conditions for both primers, while all other parameters of PCR reaction were identical, it is plausible to accept that the intensity of PCR-product bands would be a reflection of the SUR2A and Kir6.2 mRNA amounts (28). Reverse transcription polymerase chain reaction analysis demonstrated that SUR2A mRNA is present in considerably smaller amounts than Kir6.2 mRNA, which explains how it is possible that a difference in SUR2A alone is sufficient to create the differences observed in the number of cardiac KATP channels. In this regard, this is the first report to demonstrate that SUR2A subunit expression is the rate-limiting factor in the production of cardiac KATP channels.
Conclusion and significance. In conclusion, this study has demonstrated: 1) that female tissue expresses higher levels of functional cardiac KATP channels than male tissue and this is due to the higher expression of SUR2A subunit; and 2) that the observed difference may underlie the gender-specific difference in susceptibility toward heart diseases. This is the first study that demonstrated a gender-specific difference in cardiac KATP channel expression as well as the functional importance of this difference. The obtained results could provide a basis for developing therapeutic strategies against ischemic heart disease centered around KATP channels that would take into account gender-specific differences.
Study limitations. The only limitation of the study is that it was done on guinea pig and not human ventricular tissue and cells. However, bearing in mind similarities between cardiovascular systems in guinea pigs and humans, it is likely that the findings from this study pertain to humans as well.
|
Footnotes |
|---|
|
References |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
S, Jovanovi A, Shen WK, Terzic A. Low concentrations of 17ß-estradiol protect single cardiac cells against hypoxia-reoxygenation induced Ca2+ loading. J Am Coll Cardiol. 2000;36:948–952 A, Alekseev AE, Lopez JR, Shen W, Terzic A. Adenosine prevents hyperkalemia-induced calcium loading in cardiac cells: relevance for cardioplegia. Ann Thorac Surg. 1997;63:153–161 A, Gomez LA, Alekseev AE, Terzic A. Reversal of the ATP-liganded state of ATP-sensitive K+ channels by adenylate kinase activity. J Biol Chem. 1996;271:31903–31908 A, Jovanovi S, Carrasco AJ, Terzic A. Acquired resistance of a mammalian cell line to hypoxia-reoxygenation through cotransfection of Kir6.2 and SUR1 clones. Lab Invest. 1998;78:1101–1107[Medline]
A, Jovanovi S, Lorenz E, Terzic A. Recombinant cardiac ATP-sensitive K+ channel subunits confer resistance towards chemical hypoxia-reoxygenation injury. Circulation. 1998;98:1548–1555 N, Jovanovi S, Jovanovi A, Terzic A. Gene delivery of Kir6.2/SUR2A in conjunction with pinacidil handles intracellular Ca2+ homeostasis under metabolic stress. FASEB J. 1999;13:923–929This article has been cited by other articles:
|
|
 |
|
  M. A. Burke, R. K. Mutharasan, and H. Ardehali The Sulfonylurea Receptor, an Atypical ATP-Binding Cassette Protein, and Its Regulation of the KATP Channel Circ. Res., February 1, 2008; 102(2): 164 - 176. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Philip-Couderc, N. I. Tavares, A. Roatti, R. Lerch, C. Montessuit, and A. J. Baertschi Forkhead Transcription Factors Coordinate Expression of Myocardial KATP Channel Subunits and Energy Metabolism Circ. Res., February 1, 2008; 102(2): e20 - e35. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Brown and R. L. Moore Perspectives in innate and acquired cardioprotection: cardioprotection acquired through exercise J Appl Physiol, November 1, 2007; 103(5): 1894 - 1899. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. L. Lujan, V. J. Kramer, and S. E. DiCarlo Sex influences the susceptibility to reperfusion-induced sustained ventricular tachycardia and beta-adrenergic receptor blockade in conscious rats Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2799 - H2808. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Bennet, L. C. Booth, N. Ahmed-Nasef, J. M. Dean, J. Davidson, J. S. Quaedackers, and A. J. Gunn Male disadvantage? Fetal sex and cardiovascular responses to asphyxia in preterm fetal sheep Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1280 - R1286. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Chicco, M. S. Johnson, C. J. Armstrong, J. M. Lynch, R. T. Gardner, G. S. Fasen, C. P. Gillenwater, and R. L. Moore Sex-specific and exercise-acquired cardioprotection is abolished by sarcolemmal KATP channel blockade in the rat heart Am J Physiol Heart Circ Physiol, May 1, 2007; 292(5): H2432 - H2437. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. J. Gumina, D. F. O'Cochlain, C. E. Kurtz, P. Bast, D. Pucar, P. Mishra, T. Miki, S. Seino, S. Macura, and A. Terzic KATP channel knockout worsens myocardial calcium stress load in vivo and impairs recovery in stunned heart Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1706 - H1713. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. L. Moore Myocardial KATP channels are critical to Ca2+ homeostasis in the metabolically stressed heart in vivo Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1692 - H1693. [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Du, S. Jovanovic, A. Clelland, A. Sukhodub, G. Budas, K. Phelan, V. Murray-Tait, L. Malone, and A. Jovanovic Overexpression of SUR2A generates a cardiac phenotype resistant to ischemia FASEB J, June 1, 2006; 20(8): 1131 - 1141. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Johnson, R. L. Moore, and D. A. Brown Sex differences in myocardial infarct size are abolished by sarcolemmal KATP channel blockade in rat Am J Physiol Heart Circ Physiol, June 1, 2006; 290(6): H2644 - H2647. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Sakamoto, E. Zarrinpashneh, G. R. Budas, A.-C. Pouleur, A. Dutta, A. R. Prescott, J.-L. Vanoverschelde, A. Ashworth, A. Jovanovic, D. R. Alessi, et al. Deficiency of LKB1 in heart prevents ischemia-mediated activation of AMPK{alpha}2 but not AMPK{alpha}1 Am J Physiol Endocrinol Metab, May 1, 2006; 290(5): E780 - E788. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Brown, A. J. Chicco, K. N. Jew, M. S. Johnson, J. M. Lynch, P. A. Watson, and R. L. Moore Cardioprotection afforded by chronic exercise is mediated by the sarcolemmal, and not the mitochondrial, isoform of the KATP channel in the rat J. Physiol., December 15, 2005; 569(3): 913 - 924. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Bae and L. Zhang Gender Differences in Cardioprotection against Ischemia/Reperfusion Injury in Adult Rat Hearts: Focus on Akt and Protein Kinase C Signaling J. Pharmacol. Exp. Ther., December 1, 2005; 315(3): 1125 - 1135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. A Brown, J. M Lynch, C. J Armstrong, N. M Caruso, L. B Ehlers, M. S Johnson, and R. L Moore Susceptibility of the heart to ischaemia-reperfusion injury and exercise-induced cardioprotection are sex-dependent in the rat J. Physiol., April 15, 2005; 564(2): 619 - 630. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Jovanovic and A. Jovanovic High Glucose Regulates the Activity of Cardiac Sarcolemmal ATP-Sensitive K+ Channels via 1,3-Bisphosphoglycerate: A Novel Link Between Cardiac Membrane Excitability and Glucose Metabolism Diabetes, February 1, 2005; 54(2): 383 - 393. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X.-J. Du Gender modulates cardiac phenotype development in genetically modified mice Cardiovasc Res, August 15, 2004; 63(3): 510 - 519. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. van Bever, S. Poitry, C. Faure, R. I. Norman, A. Roatti, and A. J. Baertschi Pore loop-mutated rat KIR6.1 and KIR6.2 suppress KATP current in rat cardiomyocytes Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H850 - H859. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. A. Brady and A. Jovanovic The sulfonylurea controversy: Much ado about nothing or cause for concern? J. Am. Coll. Cardiol., September 17, 2003; 42(6): 1022 - 1025. [Full Text] [PDF]
|
|
|
|
 |
|
 R. M. Crawford, S. Jovanovic, G. R. Budas, A. M. Davies, H. Lad, R. H. Wenger, K. A. Robertson, D. J. Roy, H. J. Ranki, and A. Jovanovic Chronic Mild Hypoxia Protects Heart-derived H9c2 Cells against Acute Hypoxia/Reoxygenation by Regulating Expression of the SUR2A Subunit of the ATP-sensitive K+ Channel J. Biol. Chem., August 15, 2003; 278(33): 31444 - 31455. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Jovanovic, R. M. Crawford, H. J. Ranki, and A. Jovanovic Large Conductance Ca2+-Activated K+ Channels Sense Acute Changes in Oxygen Tension in Alveolar Epithelial Cells Am. J. Respir. Cell Mol. Biol., March 1, 2003; 28(3): 363 - 372. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Molero, M. Garcia-Duran, J. Diaz-Recasens, L. Rico, S. Casado, and A. Lopez-Farre Expression of estrogen receptor subtypes and neuronal nitric oxide synthase in neutrophils from women and men: Regulation by estrogen Cardiovasc Res, October 1, 2002; 56(1): 43 - 51. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Rajashree, J. C. Koster, K. P. Markova, C. G. Nichols, and P. A. Hofmann Contractility and ischemic response of hearts from transgenic mice with altered sarcolemmal KATP channels Am J Physiol Heart Circ Physiol, August 1, 2002; 283(2): H584 - H590. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. J. Ranki, G. R. Budas, R. M. Crawford, A. M. Davies, and A. Jovanovic 17{beta}-Estradiol regulates expression of KATP channels in heart-derived H9c2 cells J. Am. Coll. Cardiol., July 17, 2002; 40(2): 367 - 374. [Abstract] [Full Text] [PDF]
|
|
| |||||||
