PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 3344999

Effect of preeclampsia on carboxyhemoglobin levels: a mechanism for a decrease in P50.

J R Kambam·S Entman·S Mouton·B E Smith
View original source ↗Export metadata ↓

Abstract

COHb levels were measured in 15 preeclamptic pregnant women and 15 normal pregnant women to investigate the cause for the decrease in P50 associated with preeclampsia. The authors also included six normal and six preeclamptic pregnant patients from the above groups in the determination of P50. Measurements of COHb levels were performed in a Radiometer OSM2 Hemoximeter. Determination of P50 was done using an IL 237 Tonometer, a Radiometer, OSM2 Hemoximeter, and a Corning 168 pH/Blood Gas Analyzer. Preeclamptic pregnant patients had a mean COHb level of 2.8%, whereas normal pregnant women had a mean COHb level of 0.7% (P less than 0.001). Preeclamptic patients also had a significantly lower (24.4 mmHg) P50 than normal pregnant women (P50 = 30.1 mmHg) (P less than 0.001). The authors conclude that a significant elevation of COHb in preeclamptic pregnant women is partly responsible for a significant decrease in P50 seen in preeclampsia.

Explore related subjects

CarboxyhemoglobinFemaleHumansOxyhemoglobinsPre-EclampsiaPregnancyJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J R Kambam, S Entman, S Mouton, B E Smith. 1988. Effect of preeclampsia on carboxyhemoglobin levels: a mechanism for a decrease in P50.. https://doi.org/10.1097/00000542-198803000-00019

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1992

Picosecond phase grating spectroscopy of hemoglobin and myoglobin: energetics and dynamics of global protein motion.

Phase grating spectroscopy has been used to follow the optically triggered tertiary structural changes of carboxymyoglobin (MbCO) and carboxyhemoglobin (HbCO). Probe wavelength and temperature dependencies have shown that the grating signal arises from nonthermal density changes induced by the protein structural changes. The material displaced through the protein structural changes leads to the excitation of coherent acoustic modes of the surrounding water. The coupling of the structural changes to the fluid hydrodynamics demonstrates that a global change in the protein structure is occurring in less than 30 ps. The global relaxation is on the same time scale as the local changes in structure in the vicinity of the heme pocket. The observed dynamics for global relaxation and correspondence between the local and global structural changes provides evidence for the involvement of collective modes in the propagation of the initial tertiary conformational changes. The energetics can also be derived from the acoustic signal. For MbCO, the photodissociation process is endothermic by 21 +/- 2 kcal/mol, which corresponds closely to the expected Fe-CO bond enthalpy. In contrast, HbCO dissipates approximately 10 kcal/mol more energy relative to myoglobin during its initial tertiary structural relaxation. The difference in energetics indicates that significantly more energy is stored in the hemoglobin structure and is believed to be related to the quaternary structure of hemoglobin not present in the monomeric form of myoglobin. These findings provide new insight into the biomechanics of conformational changes in proteins and lend support to theoretical models invoking stored strain energy as the driving force for large amplitude correlated motions.

Carboxyhemoglobin↗
PubMed1992

Speed of intersubunit communication in proteins.

To determine the speed of communication between protein subunits, time-resolved absorption spectra were measured following partial photodissociation of the carbon monoxide complex of hemoglobin. The experiments were carried out using linearly polarized, 10-ns laser pulses, with the polarization of the excitation pulse both parallel and perpendicular to the polarization of the probe pulse. The substantial contribution to the observed spectra from photoselection effects was eliminated by isotropically averaging the polarized spectra, allowing a detailed comparison of the kinetics as a function of the degree of photolysis. These results show that prior to 1 microsecond both geminate ligand rebinding and conformational relaxation are independent of the number of ligands dissociated from the hemoglobin tetramer, as expected for a two-state allosteric model. After this time the kinetics depend on the ligation state of the tetramer. The conformational relaxation at 10 microseconds can be interpreted in terms of the two-state allosteric model as arising from the R to T quaternary conformational change of both unliganded and singly liganded molecules. These results suggest that communication between subunits requires about 1 microsecond and that the mechanism of the communication which occurs after this time is via the R to T conformational change. The optical anisotropy provides a novel means of accurately determining the extinction coefficients of the transient photoproduct. The decay in the optical anisotropy, moreover, provides an accurate determination of the rotational correlation time of 36 +/- 3 ns.

Carboxyhemoglobin↗