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Carotid body physiology meets cytochrome c oxidase crystallography Commentary to Ortega-Sáenz P, López-Barneo J. Physiology of the Carotid Body: From Molecules to Disease. Changing gas composition of the super-fusion medium from 20% O SB 2 sb , 3% CO SB 2 sb , 77% N SB 2 sb (normoxia) to 97% N SB 2 sb , 3% CO SB 2 sb (full hypoxia) is followed by a characteristic hypoxia-induced increased chemoreceptor sinus nerve activity (registration in black) serving as control. 1 CcO crystallographic changes of about 3 Ångström are displayed by CB chemoreceptor discharge. a Chemoreceptor discharge under normoxic and hypoxic CO application (red registration line) The effect of CO is shown as a percentage of peak chemoreceptor activity induced by 4-min hypoxia. [Extracted from the article]

A PCO electrode working on the principle of electrical conductivity is described. The calibration curve can be linearized according to the formula $$G = G_0 + b\sqrt {P{\text{CO}}_2 } $$ . This linearity has been tested in the PCO range of 0.93-9.33 kPa (7-70 Torr). For the experiments electrodes are used which have conductivity values of about 50 nS and drifts of maximally 5%/h at a PCO of 5.33 kPa (40 Torr). The response time ( T) is about 20 s. The temperature sensitivity is 2.4 nS/1 K between 298K-310K. The standard error of the measurements is σ=0.33 nS. With these electrodes tissue PCO can be measured on the surface of various organs. [ABSTRACT FROM AUTHOR]