Opioid Effects on Contractility, Ca2+-transients and Intracellular pH in Cultured Cardiac Myocytes

1993 ◽  
Vol 25 (5) ◽  
pp. 599-613 ◽  
Author(s):  
Catherine Ela ◽  
Yonathan Hasin ◽  
Yael Eilam
Keyword(s):  
Cardiac Myocytes ◽  
Intracellular Ph

scholarly journals Regulation of Intracellular pH is Altered in Cardiac Myocytes of Ovariectomized Rats

2019 ◽  
Vol 8 (7) ◽  
Author(s):  
Alejandro Martín Ibañez ◽  
María Sofía Espejo ◽  
Maite Raquel Zavala ◽  
María Celeste Villa‐Abrille ◽  
Juan Manuel Lofeudo ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Ovariectomized Rats

Intracellular pH and Ca2+ homeostasis in the pH paradox of reperfusion injury to neonatal rat cardiac myocytes

1993 ◽  
Vol 265 (1) ◽  
pp. C129-C137 ◽  
Author(s):  
J. M. Bond ◽  
E. Chacon ◽  
B. Herman ◽  
J. J. Lemasters
Keyword(s):  
Reperfusion Injury ◽  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Ischemia Reperfusion ◽  
Atp Depletion ◽  
Neonatal Rat ◽  
Metabolic Inhibitors ◽  
Simulated Ischemia ◽  
Neonatal Rat Cardiac Myocytes ◽  
Rat Cardiac Myocytes

Ischemia is characterized by anoxia and a large decrease of tissue pH. After a critical period of ischemia, reperfusion precipitates irreversible injury. Previous work showed that reperfusion injury to cultured neonatal myocytes was precipitated by a rapid return to physiological pH, a "pH paradox" (Bond, J., B. Herman, and J. Lemasters. Biochem. Biophys. Res. Commun. 179: 798-803, 1991). The aim of this study was to measure intracellular pH (pHi) and cytosolic free Ca2+ during the pH paradox of reperfusion injury to cultured neonatal rat cardiac myocytes. pHi and free Ca2+ were measured by ratio imaging of 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein and fura 2 fluorescence. To simulate ATP depletion and acidosis of ischemia, myocytes were incubated with 20 mM 2-deoxyglucose plus 2.5 mM NaCN at pH 6.2. During simulated ischemia, pHi dropped to < 6.5 and subsequently remained constant. During this time, some blebbing but little hypercontraction occurred. After 3 or 4 h of simulated ischemia, inhibitors were removed and cells were incubated at pH 7.4 to simulate reperfusion. pHi began to increase, blebbing accelerated, and myocytes hypercontracted. As pHi increased, viability was lost. The same occurred if pH was increased but metabolic inhibitors were not removed. Monensin, a Na(+)-H+ ionophore, accelerated the increase of pH after reperfusion and hastened cell killing. Hypercontraction, blebbing, and loss of viability did not occur when inhibitors were removed at pH 6.2 or in the presence of dimethylamiloride, an inhibitor of Na(+)-H+ exchange. Protection was associated with maintenance of an acidotic pHi. Free Ca2+ progressively increased during simulated ischemia. After simulated reperfusion, free Ca2+ increased further.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired posthypoxic relaxation in single cardiac myocytes: role of intracellular pH and inorganic phosphate

1993 ◽  
Vol 27 (11) ◽  
pp. 1983-1990 ◽  
Author(s):  
A. G Bertoni ◽  
S. Adrian ◽  
S. Mankad ◽  
H. S Silverman
Keyword(s):  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Inorganic Phosphate

scholarly journals 5-Aminoimidazole-4-Carboxamide-1-β-d-Ribofuranoside Reduces Glucose Uptake via the Inhibition of Na+/H+ Exchanger 1 in Isolated Rat Ventricular Cardiomyocytes

Endocrinology ◽  
2008 ◽  
Vol 149 (4) ◽  
pp. 1490-1498 ◽  
Author(s):  
Coralie Ségalen ◽  
Sarah L. Longnus ◽  
Delphine Baetz ◽  
Laurent Counillon ◽  
Emmanuel Van Obberghen
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Insulin Signaling ◽  
Glycogen Synthase ◽  
Adult Rat ◽  
Ventricular Cardiomyocytes ◽  
Isolated Cardiac Myocytes

AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that is activated by an increased AMP/ATP ratio. AMPK is now well recognized to induce glucose uptake in skeletal muscle and heart. 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) is phosphorylated to form the AMP analog ZMP, which activates AMPK. Its effects on glucose transport appear to be tissue specific. The purpose of our study was to examine the effect of AICAR on insulin-induced glucose uptake in adult rat ventricular cardiomyocytes. We studied isolated adult rat ventricular cardiomyocytes treated or not with the AMPK activators AICAR and metformin and, subsequently, with insulin or not. Insulin action was investigated by determining deoxyglucose uptake, insulin receptor substrate-1- or -2-associated phosphatidylinositol 3-kinase activity and protein kinase B (PKB) cascade using antibodies to PKB, glycogen synthase kinase-3, and Akt substrate of 160 kDa. Intracellular pH was evaluated using the fluorescent pH-sensitive dye 2′,7′-bis (2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) and Na+/H+ exchanger 1 (NHE1) activity was assessed using the NH4+ prepulse method. Our key findings are as follows. AICAR and metformin enhance insulin signaling downstream of PKB. Metformin potentiates insulin-induced glucose uptake, but surprisingly, AICAR inhibits both basal and insulin-induced glucose uptake. Moreover, we found that AICAR decreases intracellular pH, via inhibition of NHE1. In conclusion, AMPK potentiates insulin signaling downstream of PKB in isolated cardiac myocytes, consistent with findings in the heart in vivo. Furthermore, AICAR inhibits basal and insulin-induced glucose uptake in isolated cardiac myocytes via the inhibition of NHE1 and the subsequent reduction of intracellular pH. Importantly, AICAR exerts these effects in a manner independent of AMPK activation.

scholarly journals Ras triggers acidosis-induced activation of the extracellular-signal-regulated kinase pathway in cardiac myocytes

2006 ◽  
Vol 399 (3) ◽  
pp. 493-501 ◽  
Author(s):  
Robert S. Haworth ◽  
Semjidmaa Dashnyam ◽  
Metin Avkiran
Keyword(s):  
Protein Kinase ◽  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Ph Dependence ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Nucleotide Exchange ◽  
Intracellular Acidosis ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal

In cardiac myocytes, sustained (3 min) intracellular acidosis activates the ERK1/2 (extracellular-signal-regulated kinase 1/2) pathway and, through this pathway, increases sarcolemmal NHE (Na+/H+ exchanger) activity [Haworth, McCann, Snabaitis, Roberts and Avkiran (2003) J. Biol. Chem. 278, 31676–31684]. In the present study, we aimed to determine the time-dependence, pH-dependence and upstream signalling mechanisms of acidosis-induced ERK1/2 activation in ARVM (adult rat ventricular myocytes). Cultured ARVM were subjected to intracellular acidosis for up to 20 min by exposure to NH4Cl, followed by washout with a bicarbonate-free Tyrode solution containing the NHE1 inhibitor cariporide. After the desired duration of intracellular acidosis, the phosphorylation status of ERK1/2 and its downstream effector p90RSK (90 kDa ribosomal S6 kinase) were determined by Western blotting. This revealed a time-dependent transient phosphorylation of both ERK1/2 and p90RSK by intracellular acidosis (intracellular pH ∼6.6), with maximum activation occurring at 3 min and a return to basal levels by 20 min. When the degree of intracellular acidosis was varied from ∼6.8 to ∼6.5, maximum ERK1/2 phosphorylation was observed at an intracellular pH of 6.64. Inhibition of MEK1/2 [MAPK (mitogen-activated protein kinase)/ERK kinase 1/2) by pre-treatment of ARVM with U0126 or adenoviral expression of dominant-negative D208A-MEK1 protein prevented the phosphorylation of ERK1/2 by sustained intracellular acidosis, as did inhibition of Raf-1 with GW 5074 or ZM 336372. Interference with Ras signalling by the adenoviral expression of dominant-negative N17-Ras protein or with FPT III (farnesyl protein transferase inhibitor III) also prevented acidosis-induced ERK1/2 phosphorylation, whereas inhibiting G-protein signalling [by adenoviral expression of RGS4 or Lsc, the RGS domain of p115 RhoGEF (guanine nucleotide-exchange factor)] or protein kinase C (with bisindolylmaleimide I) had no effect. Our data show that, in ARVM, sustained intracellular acidosis activates ERK1/2 through proximal activation of the classical Ras/Raf/MEK pathway.

Furazolidone increases thapsigargin-sensitive Ca(2+)-ATPase in chick cardiac myocytes

1994 ◽  
Vol 267 (2) ◽  
pp. H734-H741 ◽  
Author(s):  
D. Lax ◽  
R. Martinez-Zaguilan ◽  
R. J. Gillies
Keyword(s):  
Steady State ◽  
Sarcoplasmic Reticulum ◽  
Dilated Cardiomyopathy ◽  
Cardiac Muscle ◽  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Cardiac Injury ◽  
Chick Embryos ◽  
Cardiac Muscle Cells ◽  
Induced Changes

Furazolidone is a nitrofuran antibiotic that causes dilated cardiomyopathy in turkeys and chicks and serves as an important model of human dilated cardiomyopathy. The mechanism by which furazolidone produces cardiac injury remains unknown. We investigated the hypothesis that furazolidone alters Ca2+ homeostasis in cardiac muscle cells. Myocytes harvested from 7-day-old chick embryos were treated with furazolidone (0.02, 0.1, and 1 mM) for 24–52 h and then coloaded with seminaphthorhodafluor-1 (SNARF 1) and fura 2 to measure simultaneously intracellular pH (pHi) and intracellular Ca2+ concentration ([Ca2+]i), respectively. Furazolidone did not affect steady-state [Ca2+]i levels in cardiac myocytes. Na+ removal was associated with a rapid increase in [Ca2+]i due to the Na+/Ca2+ exchanger, which was similar in control and furazolidone-treated cells. The rate of [Ca2+]i recovery after Na+ removal was significantly increased in the furazolidone-treated cells compared with controls. In most cells, recovery from Ca2+ load is accomplished by the activity of Ca(2+)-adenosinetriphosphatases (ATPases). Thapsigargin, inhibitor of sarcoplasmic reticulum Ca(2+)-ATPase, prevented the furazolidone-induced changes. These results demonstrate that furazolidone increases the activity of thapsigargin-sensitive Ca(2+)-ATPase without affecting Na+/Ca2+ exchange. These data enhance our understanding of the mechanism of furazolidone-induced injury in cardiac myocytes and may be useful in determining mechanisms of injury in dilated cardiomyopathy.

scholarly journals Experimental Generation and Computational Modeling of Intracellular pH Gradients in Cardiac Myocytes

2005 ◽  
Vol 88 (4) ◽  
pp. 3018-3037 ◽  
Author(s):  
Pawel Swietach ◽  
Chae-Hun Leem ◽  
Kenneth W. Spitzer ◽  
Richard D. Vaughan-Jones
Keyword(s):  
Computational Modeling ◽  
Cardiac Myocytes ◽  
Intracellular Ph ◽  
Ph Gradients
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