Positive staircase effect in the rat heart

1975 ◽  
Vol 228 (2) ◽  
pp. 360-364 ◽  
Author(s):  
PD Henry
Keyword(s):  
Left Ventricular Pressure ◽  
Peak Stress ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Papillary Muscles ◽  
Apparent Lack ◽  
Rat Hearts ◽  
Staircase Effect ◽  
Krebs Buffer ◽  
Isolated Rat

The apparent lack of a positive staircase effect in ray myocardium may reflect inadequate metabolic support. Isolated rat hearts (n equals 10) were perfused at 37 degrees C with Krebs buffer containing 5 mM glucose. In 10 preparations increases in heart rate from 240 to 480/min resulted in twofold increases in left ventricular pressure and dP/dt. Pacing at a rate of 480/min resulted in mechanical deterioration of the preparation and in 50% decreases of myocardial ATP concentration within a 10-min period. Hearts of open-chest rats driven at the same rate for the same period maintained normal ATP stores. In isolated papillary muscles contracting isometrically at a rate of 30/min, peak stress 15g/mm2 (mean plus or minus SE, n equals 8) and was not changed by increasing the concentration of glucose from 5 to 30 mM. When frequency was raised from 30 to 300/min, stress declined to 5.0 plus or minus .15 g/mm2 in the presence of 5mM glucose (P smaller than .001) but increased to 8.8 plus or minus .21 g/mm2 (P smaller than 0.001) in the presence of 30 mM glucose. Thus, rat ventricular myocardium exhibits a positive staircase effect at physiological heart rates when metabolic support is adequate.

Detection of Cardiac Variability in the Isolated Rat Heart

2006 ◽  
Vol 8 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Autumn M. Schumacher ◽  
Joseph P. Zbilut ◽  
Charles L. Webber ◽  
Dorie W. Schwertz ◽  
Mariann R. Piano
Keyword(s):  
Rat Heart ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Isolated Rat Heart ◽  
Rat Hearts ◽  
Before And After ◽  
Quantification Analysis ◽  
Physical Attributes ◽  
Cardiac Variability ◽  
Isolated Rat

Cardiac variability can be assessed from two perspectives: beat-to-beat performance and continuous performance during the cardiac cycle. Linear analysis techniques assess cardiac variability by measuring the physical attributes of a signal, whereas nonlinear techniques evaluate signal dynamics. This study sought to determine if recurrence quantification analysis (RQA), a nonlinear technique, could detect pharmacologically induced autonomic changes in the continuous left ventricular pressure (LVP) and electrographic (EC) signals from an isolated rat heart—a model that theoretically contains no inherent variability. LVP and EC signal data were acquired simultaneously during Langendorff perfusion of isolated rat hearts before and after the addition of acetylcholine (n = 11), norepinephrine (n = 12), or no drug (n = 12). Two-minute segments of the continuous LVP and EC signal data were analyzed by RQA. Findings showed that%recurrence,%determinism, entropy, maxline, and trend from the continuous LVP signal significantly increased in the presence of both acetylcholine and norepinephrine, although systolic LVP significantly increased only with norepinephrine. In the continuous EC signal, the RQA trend variable significantly increased in the presence of norepinephrine. These results suggest that when either the sympathetic or parasympathetic division of the autonomic nervous system overwhelms the other, the dynamics underlying cardiac variability become stationary. This study also shows that information concerning inherent variability in the isolated rat heart can be gained via RQA of the continuous cardiac signal. Although speculative, RQA may be a tool for detecting alterations in cardiac variability and evaluating signal dynamics as a nonlinear indicator of cardiac pathology.

Cardiac Effects of Postconditioning Depend Critically on the Duration of Reperfusion and Reocclusion Episodes

2010 ◽  
Vol 13 (1) ◽  
pp. 52 ◽  
Author(s):  
Bruno Botelho Pinheiro ◽  
Alfredo In�cio Fiorelli ◽  
Otoni Moreira Gomes ◽  
Borut Gersak
Keyword(s):  
Systolic Pressure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ischemic Postconditioning ◽  
Ventricular Pressure ◽  
Maximum Speed ◽  
P Value ◽  
Rat Hearts ◽  
Stabilization Period ◽  
Isolated Rat

Objective: The objective of the present study was to evaluate the effects of ischemic postconditioning on left ventricular function in isolated rat hearts.Methods: The hearts of 24 Wistar rats were were isolated, perfused immediately, and distributed into 3 groups: GI, control (n = 8); GII, three 10-second cycles of postconditioning (n = 8); and GIII, three 30-second cycles of postconditioning (n = 8). After a 15-minute stabilization period, all hearts underwent 20 minutes of global ischemia following 20 minutes of reperfusion. At times t0 (control), t5, t10, t15, and t20 (0, 5, 10, 15, and 20 minutes of reperfusion, respectively), we recorded the heart rate, coronary flow, systolic pressure, +(dP/dt)max (maximum speed of increase in the left ventricular pressure), and -(dP/dt)max (maximum speed of decrease in the left ventricular pressure). Data were analyzed by a 1-way analysis of variance, followed by the Tukey test; a P value .05); however, statistically significant differences in +(dP/dt)max between GII and GI and between GII and GIII occurred at t20 (GI, 1409.0 415.1 mm Hg/s; GII, 1917.3 403.0 mm Hg/s; GIII, 1344.8 355.8 mm Hg/s) (GII versus GI, P = .04; GII versus GIII, P = .02).Conclusion: Ischemic postconditioning with three 10-second cycles of reperfusion/reocclusion was demonstrated effective for preserving +(dP/dt)max in isolated rat hearts that underwent 20 minutes of ischemia following 20 minutes of reperfusion.

scholarly journals The Effects of Potassium Cyanide on the Functional Recovery of Isolated Rat Hearts after Ischemia and Reperfusion: The Role of Oxidative Stress

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Anica M. Petkovic ◽  
Vladimir Lj. Jakovljevic ◽  
Jovana V. Bradic ◽  
Jovana N. Jeremic ◽  
Nevena S. Jeremic ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Functional Recovery ◽  
Heart Function ◽  
Potassium Cyanide ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Global Ischemia ◽  
Albino Rats ◽  
Rat Hearts ◽  
Isolated Rat

This investigation is aimed at examining the effects of pharmacological PostC with potassium cyanide (KCN) on functional recovery, gene expression, cytochrome c expression, and redox status of isolated rat hearts. Rats were divided into the control and KCN groups. The hearts of male Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure of 70 cmH2O. After stabilisation, control hearts were subjected to global ischemia (5 minutes), followed by reperfusion (5 minutes), while experimental hearts underwent global ischemia (5 minutes) followed by 5 minutes of reperfusion with 10 μmol/L KCN. The following parameters of heart function were measured: maximum and minimum rates of pressure development, systolic and diastolic left ventricular pressure, heart rate, and coronary flow. Levels of superoxide anion radical, hydrogen peroxide, nitrites, and index of lipid peroxidation (measured as thiobarbituric acid-reactive substances) were measured in coronary venous effluent, and activity of catalase was determined in heart tissue. Expression of Bax, Bcl-2, SOD-1, SOD-2, and cytochrome c was studied as well. It was shown that expression of Bax, Bcl-2, and SOD-2 genes did not significantly differ between groups, while expression of SOD-1 gene and cytochrome c was lower in the KCN group. Our results demonstrated that KCN improved the recovery of myocardial contractility and systolic and diastolic function, enhanced catalase activity, and diminished generation of prooxidants. However, all possible mechanisms and potential adverse effects of KCN should be further examined in the future.

Mechanical workload-myocardial water content relationship in isolated rat hearts

1997 ◽  
Vol 273 (1) ◽  
pp. H271-H278
Author(s):  
E. R. Schertel ◽  
R. M. Daye ◽  
D. E. McClure ◽  
T. Lai ◽  
M. Miyamoto ◽  
...  
Keyword(s):  
Water Content ◽  
Isolated Heart ◽  
Left Ventricular Pressure ◽  
Myocardial Edema ◽  
Left Ventricular ◽  
Edema Formation ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Heart Preparation ◽  
Isolated Rat

We tested the hypothesis that the mechanical workload of the heart inversely determines the rate of myocardial edema formation in an isolated, perfused rat heart preparation. Heart rate (HR) was varied in three groups by pacing at 125 (HR125), 250 (HR250), or 350 beats/min (HR350). Left ventricular pressure (LVP) was varied in two additional groups by pacing at 250 beats/min and with the addition of either epinephrine (Epi) or propranolol (Pro) to the perfusate. In five otherwise identical groups, variation of coronary vascular resistance was minimized by adenosine. Myocardial water content (MWC) varied significantly and inversely with HR in the HR125, HR250, and HR350 groups. MWC of the HR250 group was significantly less than that of the Pro group but did not differ from the Epi group. However, when adenosine was used, MWC had significant inverse relationships with HR and LVP. We concluded that the mechanical workload of the heart inversely determines the rate and degree of myocardial edema formation in this isolated heart preparation, and both HR and LVP are determinants of this relationship.

Catecholamine–Ouabain Interaction on the Isolated Perfused Rat Heart

1975 ◽  
Vol 53 (1) ◽  
pp. 150-154 ◽  
Author(s):  
G. Tremblay ◽  
G. Porlier ◽  
V. Elharrar ◽  
R. Nadeau ◽  
J. de Champlain ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Inotropic Response ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
The Individual ◽  
6 Hydroxydopamine ◽  
Isolated Rat

The effect of catecholamine-depleting pretreatments, reserpine, and 6-hydroxydopamine (6-OH-DA) on left ventricular pressure (LVP) and the inotropic response to graded doses of ouabain (up to 300 μg/0.05 ml) was studied in isolated perfused rat and guinea-pig hearts. In rats, reserpine and 6-OH-DA depleted myocardial catecholamine content (p <0.001), increased initial LVP (p < 0.05), and virtually abolished the inotropic response to ouabain (p < 0.01). The individual maximal inotropic response to ouabain was negatively correlated with the initial LVP (r = −0.47), and this relationship was significant. In guinea pigs, reserpine and 6-OH-DA significantly depleted the cardiac content of catecholamine, but did not increase initial LVP and did not reduce the inotropic response to the highest dose of ouabain. It is concluded that in isolated rat hearts, these catecholamine-depleting pretreatments nearly abolish the inotropic response to ouabain, and this effect appears to be mediated mainly through an increase in initial LVP. The reason why catecholamine depletion failed to increase initial LVP in guinea pigs remains unexplained.

scholarly journals Electrophysiological effects of right and left vagal nerve stimulation on the ventricular myocardium

2014 ◽  
Vol 307 (5) ◽  
pp. H722-H731 ◽  
Author(s):  
Kentaro Yamakawa ◽  
Eileen L. So ◽  
Pradeep S. Rajendran ◽  
Jonathan D. Hoang ◽  
Nupur Makkar ◽  
...  
Keyword(s):  
Heart Rate ◽  
Nerve Stimulation ◽  
Regional Differences ◽  
Left Ventricular Pressure ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Vagal Nerve ◽  
Vagal Nerve Stimulation ◽  
Ventricular Pressure ◽  
Electrophysiological Effects

Vagal nerve stimulation (VNS) has been proposed as a cardioprotective intervention. However, regional ventricular electrophysiological effects of VNS are not well characterized. The purpose of this study was to evaluate effects of right and left VNS on electrophysiological properties of the ventricles and hemodynamic parameters. In Yorkshire pigs, a 56-electrode sock was used for epicardial ( n = 12) activation recovery interval (ARI) recordings and a 64-electrode catheter for endocardial ( n = 9) ARI recordings at baseline and during VNS. Hemodynamic recordings were obtained using a conductance catheter. Right and left VNS decreased heart rate (84 ± 5 to 71 ± 5 beats/min and 84 ± 4 to 73 ± 5 beats/min), left ventricular pressure (89 ± 9 to 77 ± 9 mmHg and 91 ± 9 to 83 ± 9 mmHg), and dP/d tmax (1,660 ± 154 to 1,490 ± 160 mmHg/s and 1,595 ± 155 to 1,416 ± 134 mmHg/s) and prolonged ARI (327 ± 18 to 350 ± 23 ms and 327 ± 16 to 347 ± 21 ms, P < 0.05 vs. baseline for all parameters and P = not significant for right VNS vs. left VNS). No anterior-posterior-lateral regional differences in the prolongation of ARI during right or left VNS were found. However, endocardial ARI prolonged more than epicardial ARI, and apical ARI prolonged more than basal ARI during both right and left VNS. Changes in dP/d tmax showed the strongest correlation with ventricular ARI effects ( R2 = 0.81, P < 0.0001) than either heart rate ( R2 = 0.58, P < 0.01) or left ventricular pressure ( R2 = 0.52, P < 0.05). Therefore, right and left VNS have similar effects on ventricular ARI, in contrast to sympathetic stimulation, which shows regional differences. The decrease in inotropy correlates best with ventricular electrophysiological effects.

Abstract 1712: The P2Y 12 Antagonist Cangrelor and the GP IIb/IIIa Blocker Abciximab Reduce Platelet-Mediated Myocardial Injury After Ischemia and Reperfusion

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jose A Barrabes ◽  
Javier Inserte ◽  
Maribel Mirabet ◽  
Adoracion Quiroga ◽  
Victor Hernando ◽  
...  
Keyword(s):  
Myocardial Injury ◽  
Myocardial Damage ◽  
Left Ventricular ◽  
Myocardial Salvage ◽  
Ischemia And Reperfusion ◽  
Activated Platelets ◽  
Rat Hearts ◽  
Developed Pressure ◽  
Enddiastolic Pressure ◽  
Isolated Rat

Objective: Platelets activated during experimental acute myocardial infarction (AMI) contribute to myocardial injury. We aimed to investigate whether platelets from patients with AMI increase myocardial damage after transient ischemia in isolated rat hearts and the modification of this effect by the P2Y 12 receptor antagonist cangrelor and the GPIIb/IIIa receptor blocker abciximab. Methods: Platelets were obtained from 9 AMI patients (7 thrombolyzed, all on aspirin) within 24 h after symptom onset. Incubation with 100 μM cangrelor or 50 μg/ml abciximab resulted, respectively, in 78 ± 4 and 90 ± 2% inhibition of aggregation (optical aggregometry). Isolated rat hearts (four simultaneous experiments per patient) were subjected to 40 min of global ischemia and 60 min of reperfusion. Hearts received no additional intervention (Control) or were infused during the 5 min prior to ischemia with platelets (22.5x10 6 /min), either untreated or treated with cangrelor or abciximab. Results: P-selectin expression (flow cytometry) in isolated platelets before infusion was 31 ± 3% (P = NS between groups). Platelets augmented myocardial injury, as demonstrated by worse left ventricular developed pressure (LVDevP), higher left ventricular enddiastolic pressure (LVEDP) and coronary resistance, and greater LDH release and infarct size (TTC staining), and both cangrelor and abciximab greatly attenuated these effects (Table ). Conclusions: Activated platelets from patients with AMI increase myocardial injury after ischemia and reperfusion, and cangrelor and abciximab attenuate this effect. The results support the notion that very early antiplatelet treatment may increase myocardial salvage by direct effects on the microcirculation in these patients.

scholarly journals Dose-dependent Effects of Perfluorocarbon Based Blood Substitute Perftoran on Cardyodinamics in Animal Model of Ischemia-reperfusion Injury

2021 ◽  
Author(s):  
Vladimir Jakovljevic ◽  
Sergey Vorobyev ◽  
Sergey Bolevich ◽  
Elena Morozova ◽  
Stefani Bolevich ◽  
...  
Keyword(s):  
Growth Rate ◽  
Reperfusion Injury ◽  
Rat Heart ◽  
Ex Vivo ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Isolated Rat Heart ◽  
Ischemic Reperfusion Injury ◽  
Ischemic Reperfusion ◽  
Isolated Rat

Abstract The main goal of this study was to investigate the cardioprotective properties in terms of effects on cardiodynamics of perfluorocarbon emulsion in ex vivo-induced ischemic-reperfusion injury of an isolated rat heart. The first part of the study aims to determine the dose of 10% perfluoroemulsion (PFT) that will show the best cardioprotective effect in rats on ex vivo-induced ischemic / reperfusion injury of an isolated rat heart. Depending on whether the animals received saline or PFT, the animals were divided into a control or experimental group, and depending on the application of a dose (8, 12, 16 ml / kg body weight) of saline or PFT. At a dose of 8 ml / kg, the results indicate statistically significantly lower values ​​of the maximum pressure growth rate in the group treated with 10% PFT compared to the control group treated with saline at R5 and R25 points. At a dose of 12 ml / kg, the maximum left ventricular pressure growth rate differed statistically significantly in the PFT group, ie there was an increase in this parameter at points R25 and R30, and the minimum left ventricular pressure growth rate in R15-R30 compared to saline-treated group. At a dose of 16 ml / kg, PFT also had a statistically significant effect on the change in cardiodynamic parameters in an isolated rat heart organ. Based on all the above, we can conclude that Peftoran administered immediately before ischemia (1 hour) has less positive effects on myocardial function in a model of an isolated rat heart compared to earlier administration (10 and 20 hours). Also, the effects of 10% peftoran solution are more pronounced if there is a longer period of time from application to ischemia, ie immediate application of peftoran before ischemia (1 hour) gave the weakest effects on the change of cardiodynamics of isolated rat heart.

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