A novel, remote-controlled suspension device for brain tissue PO2 measurements with multiwire surface electrodes

Abstract

A new device was developed for rapid assessment of PO2 values in viable tissue, such as the brain, using a multiwire surface electrode. The instrument utilizes a phonograph-like construction with weightless suspension of the electrode which thus minimizes surface pressure and allows for compensation of brain movements. The new and original component of the present device is the motor-driven, servo-controlled rotation of the PO2 electrode around its vertical axis. This enables PO2 measurements from precisely defined locations. From values measured on rabbit brain surface a PO2 histogram was constructed. The mean PO2 and distribution histogram were similar to those obtained with a needle electrode. The novel device, therefore, enables accurate and fast tissue PO2 measurements with minimal risk of brain damage.

Characterization in vitro and in vivo of the oxygen dependence of an enzyme/polymer biosensor for monitoring brain glucose

“…4. Thus, although the estimated concentration of brain extracellular O 2 is relatively low at approximately 50 mM (Nair et al, 1987;Murr et al, 1994), significant increases in its concentration did not affect the glucose current, supporting the O 2 interference analysis presented in Section 3.2.…”

“…Although O 2 ECF levels farthest from blood brain capillaries can be as low as 5 mM (Siesjo, 1978), electrodes the size of CPEs and Pt/PPD/GOx sensors sample the average tissue ECF concentration, estimated at Â/50 mM (Nair et al, 1987;Murr et al, 1994). We therefore calculated the percentage O 2 interference in the glucose signals at 50 mM O 2 per micromolar change in O 2 concentration (S % ), i.e., the tangential slope of plots similar to those in Fig.…”

Simultaneous measurement of cholinergic tone and neuronal network dynamics in vivo in the rat brain using a novel choline oxidase based electrochemical biosensor

“…The KmO 2 calculated from the fits averaged 2.6 ± 1.1 µM (n=4). This result shows that the sensor response is virtually insensitive to changes in O 2 above 10 µM, a value at the low end of the distribution of O 2 concentrations found in vivo (Murr et al, 1994;Nair et al, 1987).…”

“…Measurements of extracellular O 2 concentration in the neocortex and hippocampus have shown a broad distribution of O 2 basal levels around a mean of 35-50 µM but with a considerable number of observations at lower levels, down to 10 µM (Murr et al, 1994;Nair et al, 1987). The extracellular O 2 concentration is also dynamically regulated according to changes in metabolic demand imposed by neuronal activity (Lourenço et al, 2014;Masamoto and Tanishita, 2009).…”

Effects of Ultra-Purified Polymerized Bovine Hemoglobin on Local Tissue Oxygen Tension in Striated Skin Muscle – An Efficacy Study in the Hamster

“…The electrode consists of eight platinum wires and allows simultaneous monitoring of eight different tissue points by recording the pO 2 signals from a spheroid tissue volume of 12 mm in diameter. The employment of a micromanipulator [10] facilitates the gentle movement of the electrode in 8-10 0.5-mm steps permitting assessment of pO 2 at n = 64-80 local data points per animal and time point of investigation. The pO 2 values were registered from the striated skin muscle and classified into 5-mm ranges versus frequency of occurrence.…”