Negative chronotropic effect of dibutyryl cyclic AMP on the cultured chick embryonic heart cells and the prolongation of the action potential duration.

Shigenobu, Koki; Shibano, Toshiro; Kasuya, Yutaka

doi:10.1248/bpb1978.3.537

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…The rate of the spontaneous activity was 76/min in control and it was increased to 85/min 5 min after starting the ejection. The transient increase in the spontaneous activity, as was reported by SHIGENOBU et al (1980), was not observed. Rhythm and shape of action potentials in NE and EP medium is shown in Table 1.…”

Section: Methodssupporting

confidence: 55%

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Differentiation of inotropic action from chronotropic action of sympathetic agents in cultured cells of chick embryonic ventricles.

Toyota

Matsumura

1989

Jpn.J.Physiol

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The rate of the spontaneous activity of cultured cells from the chick embryonic ventricle was only slightly increased by norepinephrine (NE) or epinephrine (EP), even if it was applied close to the cell. On the other hand, the amplitude of contraction, measured from the shortening of the diameter of the cell aggregate, was clearly augmented by up to 50%. Intracellularly injected cAMP also potentiated contraction. Namely, NE, EP, or CAMP showed positive inotropic action but slight Chronotropic action on cultured ventricle cells. NE produced an increase in the action potential amplitude, shortening of action potential, and slight hyperpolarization in 17-to 19-day-old but not in 7-to 9-day-old embryo. If NE was applied to the cells whose plateau potential was inhibited by the previous treatment with nifedipine, NE recovered the plateau level to the control. Iontophoretically injected CAMP also recovered the plateau level once it had been inhibited by nifedipine or verapamil. In some cells, the membrane was transiently depolarized after the end of injection and turned back to the control level. This transient depolarization took place spontaneously again. It was suggested that the Cat +-induced Cat + release mechanism from the sarcoplasmic reticulum was involved in the cyclic depolarization.

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Section: Methodssupporting

confidence: 55%

“…SHIGENOBU et al (1980) described the transient increase in spontaneous beating rate by NE but sustained decrease by dibutyryl cyclic AMP (DBcAMP). According to HERMSMEYER and ROBINSON (1977), the cells were sensitive to the autonomic agents if they were applied close to the single cell which was beating spontaneously.…”

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confidence: 99%

Differentiation of inotropic action from chronotropic action of sympathetic agents in cultured cells of chick embryonic ventricles.

Toyota

Matsumura

1989

Jpn.J.Physiol

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Intracellular Free Ca2+ Movements in Cultured Cardiac Myocytes as Shown by Rapid Scanning Confocal Microscopy

Tanaka¹,

Kawanishi²,

Matsuda³

et al. 1996

Journal of Cardiovascular Pharmacology

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Two-dimensional images of intracellular free Ca2+ movements in cultured cardiac myocytes were obtained at 33-ms intervals with a Ca(2+)-sensitive fluorescence probe, fluo-3, and a rapid scanning confocal laser microscope, a prototype of Nikon RCM8000. The cells used were isolated from the ventricular myocardium of neonatal mice, cultured for approximately 72 h and loaded with fluo-3. One type of cytoplasmic Ca2+ movement observed was a simultaneous increase in [Ca2+] throughout the cytoplasm, termed a "spike"; another type was a local increase in [Ca2+] propagating in the cytoplasm, termed a "wave." Cells with either spike or wave or both types of movements were observed. Tetrodotoxin (TTX) 10(-5) M, nicardipine 10(-6) M, and increased extracellular potassium concentration (40 mM) selectively inhibited spike, and ryanodine 10(-6) M and cyclopiazonic acid (CPA) 3 x 10(-6) M selectively inhibited wave. These results indicate that spike was triggered by depolarization-induced Ca2+ influx across the sarcolemma, whereas wave was a propagating local increase in Ca2+ due to Ca2+ release from the sarcoplasmic reticulum (SR). On spike, nuclear [Ca2+] was shown to increase and decrease synchronously with cytoplasmic [Ca2+], with a delay and slower time course.

show abstract

Negative chronotropic effect of dibutyryl cyclic AMP on the cultured chick embryonic heart cells and the prolongation of the action potential duration.

Cited by 2 publications

References 6 publications

Differentiation of inotropic action from chronotropic action of sympathetic agents in cultured cells of chick embryonic ventricles.

Differentiation of inotropic action from chronotropic action of sympathetic agents in cultured cells of chick embryonic ventricles.

Intracellular Free Ca2+ Movements in Cultured Cardiac Myocytes as Shown by Rapid Scanning Confocal Microscopy

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