[1] Carbon perturbations leading to an increase in atmospheric CO2 are partly offset by the carbon uptake by the oceans and the rest of the climate system. Atmospheric CO2 approaches a new equilibrium state, reached after ocean invasion ceases after typically 1000 years, given by PCO2 = P0exp(dIc/IB), where P0 and PCO2 are the initial and final partial pressures of atmospheric CO2, dIc is a CO2...

The importance of intrapulmonary chemoreceptors (IPC), sensitive to PCO2 in the lung, in the control of ventilatory movements is yet to be demonstrated in the self-ventilating bird. We distinguished between the effects of PCO2 on IPC and on extrapulmonary CO2-sensitive receptors (EPC) in anaesthetized cockerels by denervating IPC in the right lung, ligating the left pulmonary artery and changin...

These experiments were designed to test the hypothesis that increases in blood flow to the lower brainstem would be greater than forebrain regions during arterial hypercapnia. Total and regional cerebral blood flow (CBF) was measured via the tracer microsphere technique in seven anesthetized New Zealand white rabbits during normocapnia (arterial PCO2 congruent to 40 torr) and hypercapnia (arter...

Culturing experiments were performed with the benthic foraminifer Ammonia aomo riensis from Flensburg Fjord, western Baltic Sea. The experiments simulated a projected rise in atmospheric CO2 concentrations. We exposed specimens to 5 seawater pCO2 levels ranging from 618 μatm (pH 7.9) to 3130 μatm (pH 7.2) for 6 wk. Growth rates and mortality differed significantly among pCO2 treatments. The hig...

When venous oxygen saturation increases as a result of increased blood flow, changes in venous blood PCO2 and carbon dioxide content may differ because of the Haldane effect. The Haldane effect may also explain increases in gastric mucosal-arterial PCO2 gradient despite major increases in splanchnic blood flow. We re-analysed data from 22 patients after cardiac surgery who were randomized to re...

The potential interactive effects of iron (Fe) limitation and Ocean Acidification in the Southern Ocean (SO) are largely unknown. Here we present results of a long-term incubation experiment investigating the combined effects of CO2 and Fe availability on natural phytoplankton assemblages from the Weddell Sea, Antarctica. Active Chl a fluorescence measurements revealed that we successfully cult...

In six patients an apnoea test was carried out to confirm brain death according to a protocol recommended in the USA. After ten minutes' apnoea the pCO2 did not reach the target value of 7.98 kPa (60 mm Hg) in any of these patients. This was caused by the low initial value and the slow increase of the pCO2. Moreover, we could not confirm the belief that the necessary duration of the apnoea test...

Since around 1950, physiological dead space - the difference between arterial and mixed expired pCO2 (partial pressure of carbon dioxide) divided by the arterial pCO2 - has been a useful clinical parameter of pulmonary gas exchange. In the previous issue of Critical Care, Niklason and colleagues remind us that physiological dead space, while easily measured, consolidates potentially very comple...

We investigated the effect of five levels pCO2-adjusted seawater (300 μatm [pre-industrial] to 1200 [near-future]) on calcification rates six coral species: Acropora nasuta, A. tenuis, Montipora digitata, Pocillopora damicornis, Porites cylindrica, and Galaxea fascicularis, which are common species in subtropical Ryukyu Archipelago, Japan. In most species, declines were pCO2-dependent as previo...

Tonometry of gastric mucosal partial carbon dioxide tension (PCO2) has been forwarded as a clinically applicable tool to monitor regional perfusion adequacy during circulatory failure. The technique is still not used widely, partly because of methodological problems. Current measurement principles are reviewed, with help of the report on PCO2 measurements in gastric juice and tonometer in this ...