Dataset Information

Raman Spectroscopic Assessment of Myocardial Viability in Langendorff-Perfused Ischemic Rat Hearts.

ABSTRACT: Spontaneous Raman spectroscopy, which senses changes in cellular contents of reduced cytochrome c, could be a powerful tool for label-free evaluation of ischemic hearts. However, undetermined is whether it is applicable to evaluation of myocardial viability in ischemic hearts. To address this issue, we investigated sequential changes in Raman spectra of the subepicardial myocardium in the Langendorff-perfused rat heart before and during ligation of the left coronary artery and its subsequent release and re-ligation. Under 532-nm wavelength excitation, the Raman peak intensity of reduced cytochrome c at 747 cm^-1 increased quickly after the coronary ligation, and reached a quasi-steady state within 30 min. Subsequent reperfusion of the heart after a short-term (30-min) ligation that simulates reversible conditions resulted in quick recovery of the peak intensity to the baseline. Further re-ligation resulted in resurgence of the peak intensity to nearly the identical value to the first ischemia value. In contrast, reperfusion after prolonged (120-min) ligation that assumes irreversible states resulted in incomplete recovery of the peak intensity, and re-ligation resulted in inadequate resurgence. Electron microscopic observations confirmed the spectral findings. Together, the Raman spectroscopic measurement for cytochrome c could be applicable to evaluation of viability of the ischemic myocardium without labeling.

SUBMITTER: Ikemoto K

PROVIDER: S-EPMC8116620 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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Raman Spectroscopic Assessment of Myocardial Viability in Langendorff-Perfused Ischemic Rat Hearts.

Ikemoto Koki K Hashimoto Kosuke K Harada Yoshinori Y Kumamoto Yasuaki Y Hayakawa Michiyo M Mochizuki Kentaro K Matsuo Kazuhiko K Yashiro Kenta K Yaku Hitoshi H Takamatsu Tetsuro T Tanaka Hideo H

Acta histochemica et cytochemica 20210417 2

Spontaneous Raman spectroscopy, which senses changes in cellular contents of reduced cytochrome c, could be a powerful tool for label-free evaluation of ischemic hearts. However, undetermined is whether it is applicable to evaluation of myocardial viability in ischemic hearts. To address this issue, we investigated sequential changes in Raman spectra of the subepicardial myocardium in the Langendorff-perfused rat heart before and during ligation of the left coronary artery and its subsequent rel ...[more]

PMID: 34012178

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Project description:Insulin exerts positive inotropic effects on cardiac muscle; however, the relationship between cardiac contractility and phosphoinositol-3-kinase/Akt (PI3K/Akt) activation remains unclear. We hypothesized that the positive inotropic effects of insulin are dose-dependent and mediated via the PI3K/Akt pathway in isolated normal rat hearts. The Institutional Animal Investigation Committee approved the use of hearts excised from rats under pentobarbital anesthesia. The hearts were perfused at a constant pressure using the Langendorff technique. After stabilization (baseline), the hearts were randomly divided into the following four insulin (Ins) groups: 1) Ins0 (0 IU/L), 2) Ins0.5 (0.5 IU/L), 3) Ins5 (5 IU/L), and 4) Ins50 (50 IU/L) (n = 8 in each group). To clarify the role of the PI3K/Akt pathway in insulin-dependent inotropic effects, we also treated the insulin groups with the PI3K inhibitor wortmannin (InsW): 5) InsW0 (0 IU/L), 6) InsW0.5 (0.5 IU/L), 7) InsW5 (5 IU/L), and 8) InsW50 (50 IU/L). Hearts were perfused with Krebs-Henseleit buffer solution with or without wortmannin for 10 min, followed by 20 min perfusion with the solution containing each concentration of insulin. The data were recorded as the maximum left ventricular derivative of pressure development (LV dP/dt max). Myocardial p-Akt levels were measured at 3 min, 5 min, and at the end of the perfusion. In the Ins groups, LV dP/dt max in Ins5 and Ins50 increased by 14% and 48%, respectively, 3 min after insulin perfusion compared with the baseline. Tachyphylaxis was observed after 10 min in the Ins5 and Ins50 treatment groups. Wortmannin partially inhibited the positive inotropic effect of insulin; although insulin enhanced p-Akt levels at all time points compared with the control group, this increase was suppressed in the presence of wortmannin. The positive inotropic effect of insulin is dose-dependent and consistent with Akt activation. This effect mediated by high doses of insulin on cardiac tissue was temporary and caused tachyphylaxis, potentially triggered by Akt overactivation, which leads beta 1 deactivation.

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Project description:BackgroundIn clinical practice, we encounter ischemic cardiomyopathy (ICM) with underlying viable, dysfunctional myocardium on a regular basis. Evidence from the Surgical Treatment for Ischemic Heart failure (STICH) and its Extension Study is supportive of improved outcomes with coronary revascularization, irrespective of myocardial viable status. However, Dobutamine stress echocardiography (DSE) and single-photon emission computed tomography (SPECT), used in STICH to assess myocardial viability may fail to distinguish hibernating myocardium from scar due to suboptimal image resolution and poor tissue characterization.HypothesisCardiac magnetic resonance (CMR) and positron emission tomography (PET) can precisely quantify myocardial scar and identify metabolically active, viable myocardium respectively. Unlike DSE and SPECT, CMR and PET allow examining myocardial status as a contiguous spectrum from viable to partially viable myocardium with varying degrees of subendocardial scar and nonviable myocardium with predominantly transmural scar, the therapeutic and prognostic determinants of ICM.MethodsUnder the guidance of CMR and PET imaging, myocardium can be distinguished viable from partially viable with subendocardial scar and predominantly transmural scar. In ICM, optimal medical therapy and coronary revascularization of viable/partially viable myocardium but not transmural scar may improve outcomes in patients with acceptable procedural risk.ResultsCoronary revascularization of partially viable and viable myocardial territory may improve clinical outcomes by preventing future ischemic, infarct events and further worsening of left ventricular remodeling and function.ConclusionsWhen deciding if coronary revascularization is appropriate in a patient with ICM, it is essential to take a patient-tailored, comprehensive approach incorporating myocardial viability, ischemia, and scar data with others such as procedural risk, and patient's comorbidities.

Dataset Information

Raman Spectroscopic Assessment of Myocardial Viability in Langendorff-Perfused Ischemic Rat Hearts.

Publications

Raman Spectroscopic Assessment of Myocardial Viability in Langendorff-Perfused Ischemic Rat Hearts.

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