It is well established that isolated intact mitochondria actively bind or accumulate various inorganic ions such as K+ and Na+ (l-9). It appears, however, that the intact mitochondrial structure may not be an absolute requirement for energy-linked active binding of inorganic ions, since Gamble (5) has demonstrated that phosphorylating digitonin fragments of rat liver mitochondria (10, 11) retai...

BACKGROUND The "topical" effect of non-steroidal anti-inflammatory drugs (NSAIDs) seems to be an important cause of NSAID induced gastrointestinal damage. AIM To examine the possible mechanism of the "topical" phase of damage in the small intestine. METHODS Electron microscopy and subcellular organelle marker enzyme studies were done in rat small intestine after oral administration of indom...

We reviewed mechanisms that determine reactive oxygen species (redox) homeostasis, redox information signaling and metabolic/regulatory function of autocrine insulin signaling in pancreatic β cells, and consequences of oxidative stress and dysregulation of redox/information signaling for their dysfunction. We emphasize the role of mitochondrion in β cell molecular physiology and pathology, incl...

Metformin is a drug widely used to treat type 2 diabetes. It enhances insulin sensitivity by improving glucose utilization in tissues like liver or muscle. Metformin inhibits respiration, and the decrease in cellular energy activates the AMP-activated protein kinase that in turn switches on catabolic pathways. Moreover, metformin increases lipolysis and beta-oxidation in white adipose tissue, t...

To determine the importance of mitochondrial reactive oxygen species toxicity in aging and senescence, we analyzed changes in mitochondrial function with age in mice with partial or complete deficiencies in the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD). Liver mitochondria from homozygous mutant mice, with a complete deficiency in MnSOD, exhibited substantial respir...

An immunodetection study of protein tyrosine phosphatase 1B (PTP-1B), SHP-2, and Src in isolated mitochondria from different rat tissues (brain, muscle, heart, liver, and kidney) revealed their exclusive localization in the brain. Given this result, we sought whether mitochondria respond to ATP and to the general tyrosine phosphatase inhibitor orthovanadate and found little or no change in the ...

The omission of K+ from the buffer used for isolation and it .cubation of rat brown fat cells blocked the large increases in respiration seen after the addition of lipolytic agents. The effect of K+ was on the activation of respiration by free fatty acids rather than upon the lipolytic action of agents such as theophylline. Rb+ and Cs+, but not NH4+, could partially substitute for K+ in the act...

PURPOSE Molecular mechanisms underlying hyperthermia-induced cellular injury are not fully understood. The aim of this study was to identify the components of mitochondrial oxidative phosphorylation affected by mild hyperthermia and to quantify the contribution of each component to changes in system behaviour. METHODS Temperature effects on the oxidative phosphorylation in isolated rat-heart ...

Ozone was found to inhibit oxidative phosphorylation and oxygen uptake in mitochondria of tobacco leaves (Nicotiana tabacum, L. var. White Gold). The inhibition appeared to occur at both substrate and electron-transport chain levels. The inhibition increased with the length of exposure to ozone, however, the phosphorylative system was more sensitive to ozone than the respiratory system. With mi...

OBJECTIVE To provide novel insights on mitochondrial respiration in β-cells and the adaptive effects of hypoxia. METHODS AND DESIGN Insulin-producing INS-1 832/13 cells were exposed to 18 hours of hypoxia followed by 20-22 hours re-oxygenation. Mitochondrial respiration was measured by high-resolution respirometry in both intact and permeabilized cells, in the latter after establishing three ...