scholarly journals Uniform sarcomere shortening behavior in isolated cardiac muscle cells.

1980 ◽  
Vol 76 (5) ◽  
pp. 587-607 ◽  
Author(s):  
J W Krueger ◽  
D Forletti ◽  
B A Wittenberg
Keyword(s):  
Cardiac Muscle ◽  
Heart Muscle ◽  
Sarcomere Length ◽  
Maximum Velocity ◽  
Diffraction Method ◽  
Muscle Cells ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Ventricular Tissue ◽  
Intact Heart

We have observed the dynamics of sarcomere shortening and the diffracting action of single, functionally intact, unattached cardiac muscle cells enzymatically isolated from the ventricular tissue of adult rats. Sarcomere length was measured either (a) continuously by a light diffraction method or (b) by direct inspection of the cell's striated image as recorded on videotape or by cinemicroscopy (120--400 frames/s). At physiological levels of added CaCl2 (0.5--2.0 mM), many cells were quiescent (i.e., they did not beat spontaneously) and contracted in response to electrical stimulation (less than or equal to 1.0-ms pulse width). Sarcomere length in the quiescent, unstimulated cells (1.93 +/- 0.10 [SD] micrometers), at peak shortening (1.57 +/- 0.13 micrometers, n = 49), and the maximum velocity of sarcomere shortening and relengthening were comparable to previous observations in intact heart muscle preparations. The dispersion of light diffracted by the cell remained narrow, and individual striations remained distinct and laterally well registered throughout the shortening-relengthening cycle. In contrast, appreciable nonuniformity and internal buckling were seen at sarcomere lengths < 1.8 micrometers when the resting cell, embedded in gelatin, was longitudinally compressed These results indicate (a) that shortening and relengthening is characterized by uniform activation between myofibrils within the cardiac cell and (b) that physiologically significant relengthening forces in living heart muscle originate at the level of the cell rather than in extracellular connections. First-order diffracted light intensity, extremely variable during sarcomere shortening, was always greatest during midrelaxation preceding the onset of a very slow and uniform phase of sarcomere relengthening.

scholarly journals Choline Permeability in Cardiac Muscle Cells of the Cat

1970 ◽  
Vol 55 (5) ◽  
pp. 602-619 ◽  
Author(s):  
S. Bosteels ◽  
A. Vleugels ◽  
E. Carmeliet
Keyword(s):  
Cell Membrane ◽  
Cardiac Muscle ◽  
Paper Chromatography ◽  
Heart Muscle ◽  
Muscle Cells ◽  
Heart Cells ◽  
Ventricular Muscle ◽  
Cardiac Cell ◽  
Cardiac Muscle Cells ◽  
Rapid Phase

Permeability of the cardiac cell membrane to choline ions was estimated by measuring radioactive choline influx and efflux in cat ventricular muscle. Maximum values for choline influx in 3.5 and 137 mM choline were respectively 0.56 and 9 pmoles/cm2·sec. In 3.5 mM choline the intracellular choline concentration was raised more than five times above the extracellular concentration after 2 hr of incubation. In 137 mM choline, choline influx corresponded to the combined loss of intracellular Na and K ions. Paper chromatography of muscle extracts indicated that choline was not metabolized to any important degree. The accumulation of intracellular choline rules out the existence of an efficient active pumping mechanism. By measuring simultaneously choline and sucrose exchange, choline efflux was analyzed in an extracellular phase, followed by two intracellular phases: a rapid and a slow one. Efflux corresponding to the rapid phase was estimated at 16–45 pmoles/cm2·sec in 137 mM choline and at 1.3–3.5 pmoles/cm2·sec in 3.5 mM choline; efflux in 3.5 mM choline was proportional to the intracellular choline concentration. The absolute figures for unidirectional efflux were much larger than the net influx values. The data are compared to Na and Li exchange in heart cells. Possible mechanisms for explaining the choline behavior in heart muscle are discussed.

scholarly journals Proto-oncogene expression in proliferating and differentiating cardiac and skeletal muscle

1987 ◽  
Vol 247 (3) ◽  
pp. 701-706 ◽  
Author(s):  
W C Claycomb ◽  
N A Lanson
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Muscle Tissue ◽  
Cellular Proliferation ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Specific Cell ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Oncogene Expression

We have examined the expression of 13 proto-oncogenes in proliferating and terminally differentiated cardiac and skeletal muscle. Total RNA was prepared from intact ventricular cardiac-muscle tissue and from purified ventricular cardiac-muscle cells of neonatal and adult rats and from cultured proliferating and terminally differentiated L6A1 rat skeletal-muscle cells. cDNA probes for histone H4, thymidine kinase, myosin heavy chain and M-creatine kinase were used to assess cellular proliferation and differentiation. Oncogenes c-myc, c-raf, c-erb-A, c-ras-H, c-ski, and c-sis were expressed in both proliferating and differentiated cardiac muscle tissue and cells, whereas c-myb expression was not observed in either. c-src was expressed only in neonatal cardiac muscle tissue and cells. c-fms, c-abl, and c-ras-K were expressed in tissue from both neonatal and adult animals but only in purified cells from neonatal animals. c-fes/fps was expressed only in neonatal cardiac muscles cells. c-fos expression was not observed in cardiac-muscle tissue from either neonatal or adult rats, but surprisingly was abundantly expressed in freshly isolated cardiac-muscle cells from animals of both ages. These results emphasize that biochemical analysis using intact cardiac-muscle tissue may not necessarily reflect muscle-specific cell processes. They also show that the expression of c-fos can be activated by the cell isolation procedure. c-myc, c-ski, c-ras-H, c-ras-K, c-abl, c-raf and c-erb-A were expressed in both proliferating and terminally differentiated skeletal-muscle cells, whereas c-myb, c-fos, c-src and c-fms transcripts were observed only in proliferating cells. c-fes/fps and c-sis were not expressed in dividing or fused skeletal-muscle cells. These results demonstrate unique tissue and cell-specific patterns of proto-oncogene expression and suggest that these genes may be involved with the regulation of cellular proliferation and terminal differentiation in striated muscle.

High-Speed Digital Data Acquisition of Sarcomere Length from Isolated Skeletal and Cardiac Muscle Cells

1983 ◽  
Vol BME-30 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Richard L. Lieber ◽  
Kenneth P. Roos ◽  
Bradford A. Lubell ◽  
James W. Cline ◽  
Ronald J. Baskin
Keyword(s):  
Data Acquisition ◽  
Cardiac Muscle ◽  
High Speed ◽  
Sarcomere Length ◽  
Muscle Cells ◽  
Digital Data ◽  
Cardiac Muscle Cells ◽  
Digital Data Acquisition

scholarly journals Preproenkephalin mRNA expression in developing rat heart and in cultured ventricular cardiac muscle cells

1989 ◽  
Vol 258 (1) ◽  
pp. 73-78 ◽  
Author(s):  
J P Springhorn ◽  
W C Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Cell Cultures ◽  
Translational Regulation ◽  
Muscle Cells ◽  
Heart Cell ◽  
Developmentally Regulated ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Developing Rat

Heart muscle tissue has previously been reported to have the highest content of preproenkephalin (ppEnk) mRNA of any tissue in the adult rat. We have determined that it is present in the ventricular cardiac muscle cells of the heart and is developmentally regulated. The expression of ppEnk mRNA was observed to be low throughout the first 2 weeks of postnatal development and decreases substantially during week 3. Expression was again low by week 4, but by adulthood (approx. 3 months), it reached a maximum. ppEnk mRNA was actively expressed in primary cardiac muscle cell cultures prepared from both neonatal and adult rats. Its steady-state content in cell cultures was observed to be increased by cyclic AMP and 3-isobutyl-1-methylxanthine. The phorbol ester phorbol 12-myristate 13-acetate elicited a transient effect (i.e. an increase was observed at 4 h and a return to control values by 24 h). We speculate that enkephalin may play a multi-functional role in the differentiation of neonatal cardiac muscle cells and in the terminally differentiated adult heart cell. We demonstrate that the primary culture systems employed in this study will be useful models with which to explore both transcriptional and translational regulation of ppEnk mRNA in the heart.

Ultrastructure of cultured atrial cardiac muscle cells from adult rats

1984 ◽  
Vol 171 (2) ◽  
pp. 191-206 ◽  
Author(s):  
R. L. Moses ◽  
William C. Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Muscle Cells ◽  
Adult Rats ◽  
Cardiac Muscle Cells

Effects of oligomycin and acidosis on rates of ATP depletion in ischemic heart muscle

1986 ◽  
Vol 250 (3) ◽  
pp. H503-H508 ◽  
Author(s):  
W. Rouslin ◽  
J. L. Erickson ◽  
R. J. Solaro
Keyword(s):  
Myocardial Ischemia ◽  
Cardiac Muscle ◽  
Heart Muscle ◽  
Ph Dependence ◽  
Muscle Cells ◽  
Atp Depletion ◽  
Ischemic Heart ◽  
Mitochondrial Atpase ◽  
Cardiac Muscle Cells ◽  
Tissue Ph

The perfusion of canine cardiac muscle with 10 microM oligomycin produced a nearly 90% slowing of the net rate of tissue ATP depletion from 0.200 to 0.025 mumol X min-1 X g wet wt-1 of tissue during a subsequent myocardial autolytic interval during which tissue pH was held constant. Moreover, lowering the tissue pH during the autolytic process by 0.6 unit from approximately 6.8 to approximately 6.2 produced a nearly 60% slowing of the net rate of tissue ATP depletion from 0.200 to 0.087 mumol X min-1 X g wet wt-1. The pH dependence of the net rate of tissue ATP depletion (by an oligomycin-sensitive process) was that predicted from the mitochondrial ATPase pH-inhibition profiles reported earlier (J. Biol. Chem. 258: 9657-9661, 1983). When taken together with our observation that the mitochondrial ATPase comprises approximately 90% of the total of all of the ATP hydrolyzing activities present in cardiac muscle cells, data reported here suggest that the protonic inhibition of the mitochondrial ATPase plays a major role in regulating the rate of tissue ATP depletion during myocardial ischemia.

THE EFFECTS OF ACUPUNCTURE ON CARDIAC MUSCLE CELLS AND BLOOD PRESSURE IN SPONTANEOUS HYPERTENSIVE RATS

2004 ◽  
Vol 29 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Hung-Chien Wu ◽  
Jaung-Geng Lin ◽  
Chun-Hsien Chu ◽  
Yung-Hsien Chang ◽  
Chung-Gwo Chang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Muscle ◽  
Muscle Cells ◽  
Hypertensive Rats ◽  
Cardiac Muscle Cells
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