scholarly journals Role of the perinodal region in atrioventricular nodal reentry: Evidence in an isolated rabbit heart preparation

1983 ◽  
Vol 2 (3) ◽  
pp. 465-473 ◽  
Author(s):  
Hiroyuki Iinuma ◽  
Leonard S. Dreifus ◽  
Todor Mazgalev ◽  
Rohn Price ◽  
Eric L. Michelson
Keyword(s):  
Rabbit Heart ◽  
Isolated Rabbit Heart ◽  
Heart Preparation

Independent role of arterial O2 tension in local control of coronary blood flow

1990 ◽  
Vol 258 (5) ◽  
pp. H1388-H1394 ◽  
Author(s):  
J. F. Baron ◽  
E. Vicaut ◽  
X. Hou ◽  
M. Duvelleroy
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Perfusion Pressure ◽  
Rabbit Heart ◽  
Coronary Resistance ◽  
Heart Preparation ◽  
Myocardial O2 Consumption ◽  
O2 Delivery ◽  
Arterial Po2

The aim of this study of a blood-perfused isolated rabbit heart preparation was to differentiate the effects on coronary resistance of large changes in arterial O2 tension (arterial PO2 = 45-400 Torr) from the effects of variations in arterial O2 content or myocardial O2 delivery. Standard stored human blood was resuspended in Krebs-Henseleit buffer and was oxygenated to obtain normal PO2, high PO2, and low PO2. Hemoglobin concentrations were adjusted to obtain the same arterial O2 content (CaO2) for the three PO2s. In a first set of experiments, in which coronary blood flow (CBF) was free and adapted to a constant perfusion pressure, switching from control [138 +/- 17 (SE) Torr] to high PO2 blood (380 +/- 27 Torr) induced a significant decrease in CBF and myocardial O2 consumption (MVO2). Switching from control (125 +/- 3 Torr) to low PO2 blood (49 +/- 5 Torr) induced a significant increase in CBF and MVO2. In a second set of experiments, the switch from control (159 +/- 5 Torr) to high PO2 (389 +/- 32 Torr) was performed in a preparation in which CBF and consequently O2 delivery were constant. Under these conditions, the increase in perfusion pressure demonstrated that PO2 affected coronary resistance, even though the O2 delivery was constant. No significant change in myocardial performance was observed in any of these experimental procedures. These results show that arterial PO2 may affect coronary blood flow regulation independently of any mediation by the autonomic nervous system and of any associated changes in O2 content or O2 delivery.

Abstract 095: Uncoupling The Mitochondria Facilitates Alternans Formation In The Isolated Rabbit Heart

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Elena Tolkacheva ◽  
Jillian Wothe ◽  
Iryna Talkachova ◽  
Rebecca Smith ◽  
Ramjay Visweswaran
Keyword(s):  
Ventricular Arrhythmias ◽  
Ischemia Reperfusion ◽  
Rabbit Heart ◽  
Mitochondrial Depolarization ◽  
Atp Production ◽  
Isolated Rabbit Heart ◽  
Whole Heart ◽  
Early Occurrence ◽  
Mitochondrial Uncoupler

Alternans of action potential duration (APD) and intracellular calcium ([Ca 2+ ] i ) transients in the whole heart are thought to be markers of increased propensity to ventricular fibrillation during ischemia reperfusion injuries. During ischemia, ATP production is affected and the mitochondria become uncoupled. This uncoupling may play an important role in alternans formation in the heart. The aim of our study was to investigate the role of mitochondrial depolarization on the formation of APD and [Ca 2+ ] i alternans in the isolated rabbit heart. We performed dual voltage and [Ca 2+ ] i optical mapping of isolated rabbit hearts under control conditions, global no-flow ischemia (n=6), and after treatment with 50 nM of the mitochondrial uncoupler FCCP (n=6). We investigated the formation of alternans of APD, [Ca 2+ ] i amplitude (CaA), and [Ca 2+ ] i duration (CaD) in the heart, under different rates of pacing. We found that treatment with FCCP leads to the early occurrence of APD (192 ± 18 ms vs 136 ± 6 ms, p<0.05), CaD (182 ± 20 ms vs 133 ± 6 ms, p<0.05), and CaA (152 ± 5 ms vs 141 ± 3 ms, p<0.05) alternans, and an increase of intraventricular APD (0.44 ± 0.02 vs 0.2 ± 0.05, p<0.05) but not CaD (0.20 ± 0.03 vs 0.16 ± 0.03, p=N/S) heterogeneity, when compared to control. On the other hand, FCCP does not affect the conduction velocity in the heart (0.95 ± 0.06 m/s vs 1.05 ± 0.11 m/s, p=N/S). Furthermore, we demonstrated that FCCP and global ischemia have similar effects on the prolongation of [Ca 2+ ] i transients, whereas ischemia induces a significantly larger reduction of APD compared to FCCP treatment. Our results demonstrate that uncoupling of mitochondria leads to earlier occurrence of alternans in the heart. Thus, in conditions of mitochondrial stress, as seen during myocardial ischemia, uncoupled mitochondria may be responsible for the formation of both APD and [Ca 2+ ] i alternans in the heart, which in turn creates a substrate conducive to formation of ventricular arrhythmias.

scholarly journals Impaired Myocardial Function and Oxygen Utilization Due to Protamine Sulfate in an Isolated Rabbit Heart Preparation

1990 ◽  
Vol 212 (4) ◽  
pp. 387-394 ◽  
Author(s):  
THOMAS W. WAKEFIELD ◽  
LARRY E. BIES ◽  
SHIRLEY K. WROBLESKI ◽  
STEVEN F. BOLLING ◽  
JAMES C. STANLEY ◽  
...  
Keyword(s):  
Myocardial Function ◽  
Rabbit Heart ◽  
Protamine Sulfate ◽  
Oxygen Utilization ◽  
Isolated Rabbit Heart ◽  
Heart Preparation

scholarly journals Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart

PLoS ONE ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. e0209085
Author(s):  
Luis Such-Miquel ◽  
Laia Brines ◽  
Antonio M. Alberola ◽  
Manuel Zarzoso ◽  
Francisco J. Chorro ◽  
...  
Keyword(s):  
Cholinergic Neurons ◽  
Rabbit Heart ◽  
Chronic Exercise ◽  
Isolated Rabbit Heart

Uncoupling the mitochondria facilitates alternans formation in the isolated rabbit heart

2013 ◽  
Vol 305 (1) ◽  
pp. H9-H18 ◽  
Author(s):  
Rebecca M. Smith ◽  
Ramjay Visweswaran ◽  
Iryna Talkachova ◽  
Jillian K. Wothe ◽  
Elena G. Tolkacheva
Keyword(s):  
Ventricular Arrhythmias ◽  
Ischemia Reperfusion ◽  
Rabbit Heart ◽  
Mitochondrial Stress ◽  
Atp Production ◽  
Isolated Rabbit Heart ◽  
Whole Heart ◽  
Early Occurrence ◽  
Mitochondrial Uncoupler

Alternans of action potential duration (APD) and intracellular calcium ([Ca2+]i) transients in the whole heart are thought to be markers of increased propensity to ventricular fibrillation during ischemia-reperfusion injuries. During ischemia, ATP production is affected and the mitochondria become uncoupled, which may affect alternans formation in the heart. The aim of our study was to investigate the role of mitochondria on the formation of APD and [Ca2+]i alternans in the isolated rabbit heart. We performed dual voltage and [Ca2+]i optical mapping of isolated rabbit hearts under control conditions, global no-flow ischemia ( n = 6), and after treatment with 50 nM of the mitochondrial uncoupler FCCP ( n = 6). We investigated the formation of alternans of APD, [Ca2+]i amplitude (CaA), and [Ca2+]i duration (CaD) under different rates of pacing. We found that treatment with FCCP leads to the early occurrence of APD, CaD, and CaA alternans; an increase of intraventricular APD but not CaD heterogeneity; and significant reduction in conduction velocity compared with that of control. Furthermore, we demonstrated that FCCP and global ischemia have similar effects on the prolongation of [Ca2+]i transients, whereas ischemia induces a significantly larger reduction of APD compared with that in FCCP treatment. In conclusion, our results demonstrate that uncoupling of mitochondria leads to an earlier occurrence of alternans in the heart. Thus, in conditions of mitochondrial stress, as seen during myocardial ischemia, uncoupled mitochondria may be responsible for the formation of both APD and [Ca2+]i alternans in the heart, which in turn creates a substrate for ventricular arrhythmias.

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