scholarly journals Ischemia Enhances the Acute Stretch-Induced Increase in Calcium Spark Rate in Ventricular Myocytes

2020 ◽  
Vol 11 ◽  
Author(s):  
Breanne A. Cameron ◽  
Hiroaki Kai ◽  
Keiko Kaihara ◽  
Gentaro Iribe ◽  
T. Alexander Quinn
Keyword(s):  
Ventricular Myocytes ◽  
Calcium Spark

Calcium spark properties in ventricular myocytes are altered in aged mice

2006 ◽  
Vol 290 (4) ◽  
pp. H1566-H1574 ◽  
Author(s):  
Susan E. Howlett ◽  
Scott A. Grandy ◽  
Gregory R. Ferrier
Keyword(s):  
Young Adult ◽  
Ventricular Myocytes ◽  
Adult Life ◽  
Field Stimulation ◽  
Calcium Spark ◽  
Age Related ◽  
Transient Rise ◽  
Decay Times ◽  
Old Mice ◽  
Age Related Changes

This study determined whether whole cell Ca2+ transients and unitary sarcoplasmic reticulum (SR) Ca2+ release events are constant throughout adult life or whether Ca2+ release is altered in aging ventricular myocytes. Myocytes were isolated from young adult (∼5 mo old) and aged (∼24 mo old) mice. Spontaneous Ca2+ sparks and Ca2+ transients initiated by field stimulation were detected with fluo-4. All experiments were conducted at 37°C. Ca2+ transient amplitudes were reduced, and Ca2+ transient rise times were abbreviated in aged cells stimulated at 8 Hz compared with young adult myocytes. Furthermore, the incidence and frequency of spontaneous Ca2+ sparks were markedly higher in aged myocytes compared with young adult cells. Spark amplitudes and spatial widths were similar in young adult and aged myocytes. However, spark half-rise times and half-decay times were abbreviated in aged cells compared with younger cells. Resting cytosolic Ca2+ levels and SR Ca2+ stores were assessed by rapid application of caffeine in fura-2-loaded cells. Neither resting Ca2+ levels nor SR Ca2+ content differed between young adult and aged cells. Thus increased spark frequency in aging cells was not attributable to increased SR Ca2+ stores. Furthermore, the decrease in Ca2+ transient amplitude was not due to a decrease in SR Ca2+ load. These results demonstrate that alterations in fundamental SR Ca2+ release units occur in aging ventricular myocytes and raise the possibility that alterations in Ca2+ release may reflect age-related changes in fundamental release events rather than changes in SR Ca2+ stores and diastolic Ca2+ levels.

CARP Plays a Key Role in Cellular Growth Under Hypertrophic Stimuli in Neonatal Rat Ventricular Myocytes

2013 ◽  
Vol 9 ◽  
Author(s):  
Tara A Shrout
Keyword(s):  
Gene Expression ◽  
Ventricular Myocytes ◽  
Cellular Growth ◽  
Neonatal Rat ◽  
Transcriptional Level ◽  
Dual Nature ◽  
Hypertrophic Growth ◽  
Rat Ventricular Myocytes ◽  
Neonatal Rat Ventricular Myocytes ◽  
Over Time

Cardiac hypertrophy is a growth process that occurs in response to stress stimuli or injury, and leads to the induction of several pathways to alter gene expression. Under hypertrophic stimuli, sarcomeric structure is disrupted, both as a consequence of gene expression and local changes in sarcomeric proteins. Cardiac-restricted ankyrin repeat protein (CARP) is one such protein that function both in cardiac sarcomeres and at the transcriptional level. We postulate that due to this dual nature, CARP plays a key role in maintaining the cardiac sarcomere. GATA4 is another protein detected in cardiomyocytes as important in hypertrophy, as it is activated by hypertrophic stimuli, and directly binds to DNA to alter gene expression. Results of GATA4 activation over time were inconclusive; however, the role of CARP in mediating hypertrophic growth in cardiomyocytes was clearly demonstrated. In this study, Neonatal Rat Ventricular Myocytes were used as a model to detect changes over time in CARP and GATA4 under hypertrophic stimulation by phenylephrine and high serum media. Results were detected by analysis of immunoblotting. The specific role that CARP plays in mediating cellular growth under hypertrophic stimuli was studied through immunofluorescence, which demonstrated that cardiomyocyte growth with hypertrophic stimulation was significantly blunted when NRVMs were co-treated with CARP siRNA. These data suggest that CARP plays an important role in the hypertrophic response in cardiomyocytes.

Reduced Contraction and Altered Frequency Response of Isolated Ventricular Myocytes From Patients With Heart Failure

Circulation ◽  
1995 ◽  
Vol 92 (9) ◽  
pp. 2540-2549 ◽  
Author(s):  
C.H. Davies ◽  
K. Davia ◽  
J.G. Bennett ◽  
J.R. Pepper ◽  
P.A. Poole-Wilson ◽  
...  
Keyword(s):  
Heart Failure ◽  
Frequency Response ◽  
Ventricular Myocytes ◽  
Patients With Heart Failure ◽  
Isolated Ventricular Myocytes
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