An abrupt increase in ambient CO2 resulted in a marked respiratory acidosis which took place within 30 min. During this time there was a considerable reduction in the PCO2 difference between arterial blood and inspired gas caused by an increase in ventilations. Prolonged CO2 exposure (24 h) showed that there was some compensation for the acidosis in that plasma bicarbonate concentrations increa...

We determined the effect of alterations in coronary arterial PCO2 on coronary vascular resistance (CVR) at a constant coronary sinus (CS) PO2 and the effect of coronary arterial PO2 variation on CVR at a constant CS PCO2. A linear but opposing effect on CVR was found for both gases. The sensitivity of CVR to O2 change, represented as CVR/CS PO2, was approximately twice that of the ratio CVR/CS ...

One hundred and fifty eight paired arterial and capillary blood samples were obtained from 41 sick preterm infants in their first week of life and the pH, and PCO2, and PO2 concentrations were measured. Half of the capillary samples were obtained from unwarmed heels and half from heels warmed to 40 degrees C. A potentially significant discrepancy (arbitrarily defined as 0.05 units for pH. 1 kPa...

The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO2 in the widespread and abundant coccolithophore Emi...

Ocean acidification is predicted to impair marine calcifiers' abilities produce shells and skeletons. We conducted laboratory experiments investigating the impacts of CO2-induced ocean (pCO2 = 478–519, 734–835, 8,980–9,567; Ωcalcite 7.3–5.7, 5.6–4.3, 0.6–0.7) on calcification rates two estuarine calcifiers involved in a classic predator-prey model system: adult Panopeus herbstii (Atlantic mud c...

Pulmonary and systemic arterial carbon dioxide tensions (Pco2) were measured at cardiac catheterization in I.f patients with left-to-right circulatory shunts and in irS patients with valvular heart disease. The measurements were performed under resting conditions and at 5-sec intervals during a 30-sec period of hyperventilation. In both groups the systemic arterial Pco2 fell significantly durin...

The late Paleozoic deglaciation is the vegetated Earth's only recorded icehouse-to-greenhouse transition, yet the climate dynamics remain enigmatic. By using the stable isotopic compositions of soil-formed minerals, fossil-plant matter, and shallow-water brachiopods, we estimated atmospheric partial pressure of carbon dioxide (pCO2) and tropical marine surface temperatures during this climate t...

Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility may leave animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore important to determine whether scleractinian corals have the plasticity to adapt and pro...

In densely populated communities, such as coral reefs, organisms can modify the physical and chemical environment for neighbouring individuals. We tested the hypothesis that colony density (12 colonies each placed ∼0.5 cm apart versus ∼8 cm apart) can modulate the physiological response (measured through rates of calcification, photosynthesis and respiration in the light and dark) of the coral ...

The variability of the carbon dioxide in the eastern North Atlantic Ocean was investigated by studying three seasons with different hydrographical and meteorological conditions that lead to two main different situations: upwelling and downwelling. No correlation between surface pCO2 and chlorophyll was found in spring, although significant correlation was found in autumn when strong downwelling...