title: Optical Cryoimaging Reveals a Heterogeneous Distribution of Mitochondrial Redox State in ex vivo Guinea Pig Hearts and Its Alteration During Ischemia and Reperfusion.
abstract: Oxidation of substrates to generate ATP in mitochondria is mediated by redox reactions of NADH and FADH2. Cardiac ischemia and reperfusion (IR) injury compromises mitochondrial oxidative phosphorylation. We hypothesize that IR alters the metabolic heterogeneity of mitochondrial redox state of the heart that is only evident in the 3-D optical cryoimaging of the perfused heart before, during, and after IR. The study involved four groups of hearts: time control (TC: heart perfusion without IR), global ischemia (Isch), global ischemia followed by reperfusion (IR) and TC with PCP (a mitochondrial uncoupler) perfusion. Mitochondrial NADH and FAD autofluorescence signals were recorded spectrofluorometrically online in guinea pig ex vivo-perfused hearts in the Langendorff mode. At the end of each specified protocol, hearts were rapidly removed and snap frozen in liquid N2 for later 3-D optical cryoimaging of the mitochondrial NADH, FAD, and NADH/FAD redox ratio (RR). The TC hearts revealed a heterogeneous spatial distribution of NADH, FAD, and RR. Ischemia and IR altered the spatial distribution and caused an overall increase and decrease in the RR by 55% and 64%, respectively. Uncoupling with PCP resulted in the lowest level of the RR (73% oxidation) compared with TC. The 3-D optical cryoimaging of the heart provides novel insights into the heterogeneous distribution of mitochondrial NADH, FAD, RR, and metabolism from the base to the apex during ischemia and IR. This 3-D information of the mitochondrial redox state in the normal and ischemic heart was not apparent in the dynamic spectrofluorometric data.
authors: Department of Electrical EngineeringUniversity of Wisconsin-MilwaukeeMilwaukeeWI53211USA; Biotechnology and Bioengineering CenterMedical College of WisconsinMilwaukeeWI53226USA.
authors: Mahsa
authors: M
authors: Ranji
authors: Department of Electrical Engineering University of Wisconsin-Milwaukee Milwaukee WI 53211 USA.
authors: Mohammad Masoudi
authors: MM
authors: Motlagh
authors: Department of Electrical Engineering University of Wisconsin-Milwaukee Milwaukee WI 53211 USA.
authors: Fahimeh
authors: F
authors: Salehpour
authors: Department of Electrical Engineering University of Wisconsin-Milwaukee Milwaukee WI 53211 USA.
authors: Reyhaneh
authors: R
authors: Sepehr
authors: Department of Anesthesiology Medical College of Wisconsin Milwaukee WI 53226 USA.
authors: James S
authors: JS
authors: Heisner
authors: Department of PhysiologyMedical College of WisconsinMilwaukeeWI53226USA; Biotechnology and Bioengineering CenterMedical College of WisconsinMilwaukeeWI53226USA; Cardiovascular Research CenterMedical College of WisconsinMilwaukeeWI53226USA.
authors: Ranjan K
authors: RK
authors: Dash
authors: Cardiovascular Research CenterMedical College of WisconsinMilwaukeeWI53226USA; Department of AnesthesiologyMedical College of WisconsinMilwaukeeWI53226USA.
authors: Amadou K S
authors: AK
authors: Camara
keywords: Optical cryoimaging; ischemia and reperfusion; metabolism; mitochondria; redox state