Frequency, amplitude, and propagation velocity of spontaneous Ca++-dependent contractile waves in intact adult rat cardiac muscle and isolated myocytes

A. A. Kort, M. C. Capogrossi, Edward Lakatta

Research output: Contribution to journalArticle

Abstract

Spontaneous contractile waves due to spontaneous calcium cycling by the sarcoplasmic reticulum occur in unstimulated bulk rat papillary muscle and single rat cardiac myocytes with intact sarcolemmal function. We used video analytic techniques to quantify the wave characteristics in both bulk muscle and myocytes; laser-light scattering techniques were also employed in muscle. In muscle bathed in physiological concentrations of calcium, the true periodicity of these waves was a fraction of 1 Hz and increased up to several hertz with increases in cell calcium. This was paralleled by an increase in the frequency of scattered laser light intensity fluctuations. In myocytes, a range of spontaneous contractile wave frequencies similar to that which occurred in the muscle was observed; it could be demonstrated that an increase in superfusate calcium concentrations (2-15 mm at 23° ) increases the oscillation frequency but not amplitude. In both myocytes and muscle, low concentrations of caffeine (0.5 mm) and higher temperature increased the oscillation frequency but diminished their amplitude. However, the scattered light fluctuations did not change with temperature and decreased with caffeine. These results demonstrate that (1) the true frequency of spontaneous sarcoplasmic reticulum oscillations in the unstimulated rat muscle and single myocytes with intact sarcolemmal function is low, i.e., a fraction of a hertz; (2) with cell calcium loading, the oscillation frequency accelerates to those fequencies measured previously in the 'calcium overload' state; (3) while scattered light fluctuations which sample myofilament motion are a sensitive, noninvasive method of detecting the oscillations in bulk muscle, they can be insensitive to the divergent changes in oscillation amplitude and frequency.

Original languageEnglish (US)
Pages (from-to)844-855
Number of pages12
JournalCirculation Research
Volume57
Issue number6
StatePublished - 1985
Externally publishedYes

Fingerprint

Muscle Cells
Myocardium
Muscles
Calcium
Light
Sarcoplasmic Reticulum
Caffeine
Lasers
Temperature
Calcium Signaling
Papillary Muscles
Myofibrils
Periodicity
Cardiac Myocytes

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Frequency, amplitude, and propagation velocity of spontaneous Ca++-dependent contractile waves in intact adult rat cardiac muscle and isolated myocytes. / Kort, A. A.; Capogrossi, M. C.; Lakatta, Edward.

In: Circulation Research, Vol. 57, No. 6, 1985, p. 844-855.

Research output: Contribution to journalArticle

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