The meaning of H2O2 generation in carotid body cells for PO2 chemoreception.

The rat carotid body is able to generate H2O2 in type-I cells with the aid of an electron-transferring chain with cytochrome b as the major component as it can be detected by spectrophotometry as well as confocal laser-microscopy. This cytochrome b is reducible by hypoxia, but not by cyanide, indicating that it does not participate in the energy production by the respiratory chain. The carotid body possesses a glutathione peroxidase (GPO) which scavenges H2O2 and other organic hydroperoxides.

Effects of amiloride treatment on U-118 MG and U-251 MG human glioma and HT-29 human colon carcinoma cells.

Human glioma (U-118 MG, U-251 MG) and human colon carcinoma (HT-29) spheroids and monolayers were continuously exposed to amiloride under physiological Na+ and HCO3- conditions. Amiloride in concentrations of 0.1-0.

Indications to an NADPH oxidase as a possible pO2 sensor in the rat carotid body.

The rat carotid body superfused with low pO2 exhibited an optical absorbance spectrum which resembles the reduced spectrum of the NADPH oxidase in neutrophils. Diphenylene iodonium (DPI) as a specific inhibitor of the oxidase attenuated the reduced absorbance spectrum in the carotid body. Also absorbance bleaching by low doses of cyanide (50 and 100 microM) was inhibited by DPI, whereas higher doses of cyanide (300 microM) caused an absorbance spectrum typical for reduced cytochromes.

Triple-barrelled ion-sensitive microelectrode for simultaneous measurements of two extracellular ion activities.

A method has been described by which triple-barrelled ion-sensitive microelectrodes for simultaneous measurements of two extracellular ion activities could be produced with a tip diameter of 1-2 microns. The following combinations with two ion exchangers could be achieved: Ca++/K+, Ca++/Cl-, K+/Na+. The mean steepness for the potassium electrode was 55.