Isolation of calcium tolerant myocytes from adult rat hearts: Review of the literature and description of a method

Farmer, Barbara B.; Mancina, Michael; Williams, Eric S.; Watanabe, August M.

doi:10.1016/0024-3205(83)90706-3

Cited by 112 publications

(46 citation statements)

References 56 publications

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“…Single ventricular myocytes were isolated from either ventricle of adult female or male Sprague-Dawley rats (Charles River Breeding Laboratories, Charles River, MA) weighing -200-225 g. The isolation procedure was a modification of methods described by Farmer et al (1983) and Sbeu et al (1984). Myocytes were also obtained from adult guinea pigs using an isolation procedure similar to that described by Mitra and Morad (1985).…”

Section: Methodsmentioning

confidence: 99%

Hydrogen ion modulation of Ca channel current in cardiac ventricular cells. Evidence for multiple mechanisms.

Krafte

Kass

1988

The Journal of General Physiology

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We have investigated the effects of H ions on (L-type) Ca channel current in isolated ventricular cells. We find that the current amplitude is enhanced in solutions that are alkaline relative to pH 7.4 and reduced in solutions acidic to this pH. We measured pHo-induced shifts in channel gating and analyzed our results in terms of surface potential theory. The shifts are well described by changes in surface potential caused by the binding of H ions to negative charges on the cell surface. The theory predicts a pK of 5.8 for this binding. Gating shifts alone cannot explain all of our observations on modulation of current amplitude. Our results suggest that an additional mechanism contributes to modification of the current amplitude.

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Section: Methodsmentioning

confidence: 99%

Hydrogen ion modulation of Ca channel current in cardiac ventricular cells. Evidence for multiple mechanisms.

Krafte

Kass

1988

The Journal of General Physiology

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“…Single ventricular myocytes were enzymatically isolated using essentially standard procedures (Farmer, Mancina, Williams & Watanabe, 1983). Briefly, 4-to 6-month-old Wistar rats were given an intraperitoneal injection of 2000 units of heparin and killed 20 min later by cervical dislocation.…”

Section: Isolation Of Ventricular Myocytesmentioning

confidence: 99%

A persistent sodium current in rat ventricular myocytes.

Saint

Gage

1992

The Journal of Physiology

191

146

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SUMMARY1. The tight seal, whole-cell, voltage-clamp technique was used to record currents from single ventricular myocytes acutely dissociated from adult rat hearts. Subtraction of currents recorded in the presence and absence of tetrodotoxin (TTX, 50 /SM) revealed a small, persistent, inward current following a much larger, transient, inward current.2. Both currents were sodium currents because they reversed close to the sodium equilibrium potential and were depressed when choline was substituted for extracellular sodium.3. The persistent sodium current could be recorded when the transient current had been inactivated with conditioning depolarization. Only slight inactivation of the persistent current occurred during depolarizing pulses lasting up to 900 ms. 4. A lower concentration of TTX (0-1 /,lM) blocked the persistent sodium current while having little effect on the transient sodium current.5. The persistent sodium current was activated at more negative potentials than the transient sodium current. It cannot have been a window current because it was recorded at positive potentials when the transient current was completely inactivated.6. Because the persistent and transient sodium currents had a different voltage dependence and sensitivity to TTX, it was concluded that different channels are responsible for the two currents.

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“…Isolated ventricular myocytes were obtained from guinea pigs (weighing 200-300 g) by a collagenase dissociation technique. 14 Briefly, hearts were perfused through the aorta and coronary arteries with a nominally calcium-free solution for approximately 1 minute followed by a 10-20-minute perfusion with solution containing 0.15% (123-153 units/mg, Worthington type II) collagenase and 50 ,M CaCl2. After the perfusion with enzyme, the heart was minced and gently agitated in a shaking water bath at 370 C. Cells were washed three times in enzyme-free solution supplemented with 1 mg/ml bovine serum albumin (Sigma Chemical, St Louis, Missouri) and 0.05, 0.1, and 0.5 mM CaCl2, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…His lidocaine level 4 hours after beginning the infusion was 2.9 ,g/ml, and the GX concentration was 0.1 gg/ml. His arrhythmia slowly returned within [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] hours with an average of 300 ventricular premature depolarizations/hr and occasional runs of unsustained ventricular tachycardia. His plasma lidocaine concentration at that time was 3.1 gag/ml, and the GX concentration was 0.8 ,ug/ml.…”

Section: Patientsmentioning

confidence: 99%

Competition between lidocaine and one of its metabolites, glycylxylidide, for cardiac sodium channels.

1988

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The modulated receptor hypothesis states that sodium channels have a specific receptor for antiarrhythmic drugs. Therefore, two agents that block sodium channels by binding to this receptor are expected to compete for occupancy. Glycylxylidide (GX) is a deethylated metabolite of lidocaine that accumulates in patients on lidocaine therapy. In single, voltage-clamped cardiocytes, GX, like lidocaine, blocked cardiac sodium channels in a use-dependent manner. However, its kinetics of recovery from block were markedly different from lidocaine: at potentials between -80 and -100 mV, GX-blocked channels recovered faster and more completely than lidocaine-blocked channels but recovered more slowly at more negative potentials (-120 to -140 mV). If lidocaine and GX compete for a common receptor, then there are conditions in which addition of a "faster" drug to a "slower" drug will produce less block than the slower drug alone. At potentials between -120 and -140 mV, addition of GX (slower drug) to lidocaine always increased the level of block, but addition of lidocaine to GX decreased the block in four of nine experiments and did not increase it in three of nine experiments. Conversely, at potentials between -80 and -100 mV, addition of lidocaine (slower drug) to GX always increased block, whereas addition of GX to lidocaine reduced the level of block in five of 16 experiments and did not increase it in seven of 16 experiments. Thus, upon addition of more blocker, the sodium current increased in 36% of cases or did not decline in 76% of cases. These results can be explained by the modulated receptor hypothesis with two drugs competing for the same receptor. This is the first demonstration of an antiarrhythmic drug metabolite that can competitively displace its parent compound in vitro. Whether competitive displacement of a parent compound by a metabolite also occurs in humans will require clinical studies.

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Isolation of calcium tolerant myocytes from adult rat hearts: Review of the literature and description of a method

Cited by 112 publications

References 56 publications

Hydrogen ion modulation of Ca channel current in cardiac ventricular cells. Evidence for multiple mechanisms.

Hydrogen ion modulation of Ca channel current in cardiac ventricular cells. Evidence for multiple mechanisms.

A persistent sodium current in rat ventricular myocytes.

Competition between lidocaine and one of its metabolites, glycylxylidide, for cardiac sodium channels.

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