In order to assess the quality of freshly isolated and cultivated pancreatic islets designed for experimental transplantation in rats we combined the vitality staining test, in vitro measurement of insulin secretion capacity, and assessment of islet respiration. Oxygen consumption was measured using the respirometer Oxygraph 2K equipped with polarographic oxygen sensors. The results of oxymetry demonstrated a linear correlation between islet number and oxygen consumption. Respiration per unit of viable islet tissue was constant. Oxygen consumption tests were in good correlation with the results of insulin release assays, with a correlation coefficient of 0.82. We found no significant differences in all three vitality-testing methods performed with fresh and 24-hour cultivated islets (P > .05). We conclude that polarographic oxymetry provides a fast and easy evaluation test of islet quality. After appropriate standardization, the oxymetric technique can be used for routine clinical pretransplant islet quality testing. In addition, cell membrane integrity and mitochondrial function could be assessed after addition of specific respiration inhibitors or stimulators.
- MeSH
- Insulin secretion MeSH
- Rats MeSH
- Cells, Cultured MeSH
- Islets of Langerhans * cytology physiology secretion MeSH
- Oximetry methods MeSH
- Rats, Wistar MeSH
- Oxygen Consumption * physiology MeSH
- Cell Survival MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
UNLABELLED: Remote ischemic preconditioning (RIP)-induced protection of myocardial energetics was well documented on the level of tissue, but data concerning the involvement of mitochondria were missing. We aimed at the identification of changes in membrane properties and respiratory functions induced in rat heart mitochondria by RIP. Experiments were performed on 46 male Wistar rats divided into control and RIP-treated groups of 21 animals each. Blood flow in the occluded area was recorded by MRI angiography in four animals. RIP protocol comprised of three successive 5-min occlusions each followed by 5-min reperfusions of descending branches of the right hind limb femoral artery. The efficacy of RIP was evaluated as the extent of RIP-induced protection against damage to the functions of mitochondria isolated by differential centrifugation after 30-min global ischemia followed by 40-min reperfusion of the hearts in Langendorff mode. ASSESSMENTS: mitochondrial membrane fluidity with a fluorescent probe DPH, CoQ(9) and CoQ(10) with HPLC, mitochondrial respiration with the Oxygraph-2k (Oroboros). Results revealed that RIP was affecting the mitochondria. The immediate protection conferred by RIP involves beneficial and prognostically significant effects: a total elimination of ischemia/reperfusion-induced depression of mitochondrial membrane fluidity and a trend for better preservation of mitochondrial state 3 respiration.
- MeSH
- Cell Membrane metabolism MeSH
- Ischemic Preconditioning, Myocardial * MeSH
- Extremities blood supply MeSH
- Oxidative Phosphorylation MeSH
- Rats, Wistar MeSH
- Mitochondria, Heart metabolism MeSH
- Electron Transport MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Mitochondria play an essential role in improved cardiac ischaemic tolerance conferred by adaptation to chronic hypoxia. In the present study, we analysed the effects of continuous normobaric hypoxia (CNH) on mitochondrial functions, including the sensitivity of the mitochondrial permeability transition pore (MPTP) to opening, and infarct size (IS) in hearts of spontaneously hypertensive rats (SHR) and the conplastic SHR-mt(BN) strain, characterized by the selective replacement of the mitochondrial genome of SHR with that of the more ischaemia-resistant brown Norway (BN) strain. Rats were adapted to CNH (10% O2, 3 weeks) or kept at room air as normoxic controls. In the left ventricular mitochondria, respiration and cytochrome c oxidase (COX) activity were measured using an Oxygraph-2k and the sensitivity of MPTP opening was assessed spectrophotometrically as Ca(2+)-induced swelling. Myocardial infarction was analysed in anaesthetized open-chest rats subjected to 20 min of coronary artery occlusion and 3 h of reperfusion. The IS reached 68±3.0% and 65±5% of the area at risk in normoxic SHR and SHR-mt(BN) strains, respectively. CNH significantly decreased myocardial infarction to 46±3% in SHR. In hypoxic SHR-mt(BN) strain, IS reached 33±2% and was significantly smaller compared with hypoxic SHR. Mitochondria isolated from hypoxic hearts of both strains had increased detergent-stimulated COX activity and were less sensitive to MPTP opening. The maximum swelling rate was significantly lower in hypoxic SHR-mt(BN) strain compared with hypoxic SHR, and positively correlated with myocardial infarction in all experimental groups. In conclusion, the mitochondrial genome of SHR modulates the IS-limiting effect of adaptation to CNH by affecting mitochondrial energetics and MPTP sensitivity to opening.
- MeSH
- Chronic Disease MeSH
- Genome, Mitochondrial genetics MeSH
- Hypoxia * MeSH
- Myocardial Infarction genetics metabolism pathology MeSH
- Rats MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondrial Proteins genetics metabolism MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- Rats, Inbred BN MeSH
- Rats, Inbred SHR MeSH
- Rats, Transgenic MeSH
- Myocardial Reperfusion Injury genetics metabolism physiopathology MeSH
- Electron Transport Complex IV genetics metabolism MeSH
- Mitochondria, Heart genetics metabolism MeSH
- Mitochondrial Membrane Transport Proteins metabolism MeSH
- Blotting, Western MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
