Results of intraperitoneal microdialysis depend on the location of the catheter.

BACKGROUND AND OBJECTIVE: Intraperitoneal microdialysis was recently described as a method for early detection of visceral ischemia. The method seems safe and accurate. The intra-abdominal catheter used may imply variations in results depending on the location of the catheter. The aim of the study was to investigate possible differences in metabolic parameters obtained depending on various locations of the intra-abdominal catheter, compared with using the subcutaneous reference catheter. METHOD: After right-sided hemicolectomy in 12 patients, three catheters were placed and fixed intraperitoneally: one at the anastomosis, one in the omentum and one embedded between the small intestinal loops. A subcutaneous catheter placed in the pectoral region was used as reference. Analyses of lactate/pyruvate ratio and glucose and glycerol levels were done during a period of 45 hours postoperatively. RESULTS: Lactate/pyruvate ratio decreased numerically at all three intraperitoneal locations during the study while the subcutaneous lactate/pyruvate ratio increased slightly. Significant differences between intraperitoneal and subcutaneous locations were found as well as differences between the three intraperitoneal locations. Highest values of the lactate/pyruvate ratio were found at the anastomosis, while the widest range was found at the small intestine. Subcutaneous glucose levels were lower while glycerol levels were higher compared with intraperitoneal values. CONCLUSIONS: In evaluating postoperative metabolism, intraperitoneal microdialysis is influenced by the location of the microdialysis catheter. The same pattern is, however, recorded over time. The juxta-anastomotic region and the small intestinal loop area seem to be the most reasonable locations for measurements.

Adrenaline potentiates PI 3-kinase in platelets stimulated with thrombin and SFRLLN: role of secreted ADP.

Adrenaline significantly potentiated late thrombin- and SFRLLN-induced PtdIns(3,4)P(2) production. Furthermore, the potentiating effect of adrenaline on thrombin-induced PtdIns(3, 4)P(2) production was independent on secreted ADP, whereas, the effect of adrenaline on SFRLLN-induced PtdIns(3,4)P(2) production was completely dependent of secreted ADP. However, the ADP-dependent accumulation of PtdIns(3,4)P(2) was not required for irreversible platelet aggregation induced by SFRLLN in the presence of adrenaline. It is concluded that adrenaline can replace secreted ADP to potentiate PtdIns(3,4)P(2) production in thrombin-stimulated but not in SFRLLN-stimulated platelets, thus demonstrating a qualitative difference between platelet stimulation by thrombin and the thrombin receptor activating peptide SFRLLN.

Genetic variation and functional properties of Atlantic cod hemoglobins: introducing a modified tonometric method for studying fragile hemoglobins.

Hemoglobin polymorphism in Atlantic cod has been investigated with respect to physiological performance at 10, 15 and 20 degrees C applying a modified tonometric method for O2 equilibrium analysis with full control of the equilibrating gas mixture. The results did not indicate any dissociation of the hemoglobins by a reduction in cooperativity and a parallel increase in affinity during the analytical procedure in contrast to the original tonometric method. With the applied preparation technique, we could store the hemolysate for 70 days at -25 degrees C without any significant changes in the O2 binding properties (P < 0.05) demonstrating the high quality of this procedure for analysing fragile fish hemoglobins. The present investigation demonstrates that the oxygen affinity of the hemoglobins varied between the genotypes. At all temperatures, except 20 degrees C and pH 8.0, Hb-I(2/2) had a higher O2 affinity than Hb-I(1/1). These results conform with previous results (16), suggesting Hb-I(2/2), the genotype which is the dominant allele in northern areas, to be the most efficient O2 carrier at low temperatures. The highest O2 affinity, however, was found for Hb-I(2/2b), supporting the results of Fyhn et al. (9), that this genotype is more restricted to coastal and warmer water and thus a better marker of the coastal population. Our results further suggest a correlation between genotype specific growth rates and oxygen affinities at all temperatures studied, with the highest growth rates observed in those genotypes having the highest O2 affinities. In conclusion, the hemoglobin polymorphism of cod seems to be correlated with physiological performance.

Functional characterisation of Eskimo dog hemoglobin: I. Interaction of Cl- and 2,3-DPG and its importance to oxygen unloading at low temperature.

The oxygen binding properties of hemoglobin and some hematological parameters in Eskimo dogs (belonging to Canis lupus familiaris) in Ilulissat/Jacobshavn, Greenland were analysed. The average [2,3-DPG] and [Hb] (n = 16) were 3.14 +/- 0.34 mmol l-1 blood and 9.53 +/- 0.65 g dl-1 (1.49 mmol l-1), respectively, giving a stoichiometric ratio of 2.11 mol 2,3-DPG/mol Hb. Oxygen binding analysis carried out on hemolysate in HEPES buffer at 20 and 37 degrees C revealed a high oxygen affinity (1.2 mmHg at pH 7.4, 20 degrees C) in the desalted condition, which decreased markedly in the presence of chloride and 2,3-DPG. A low apparent equilibrium constant for the binding of 2,3-DPG (1.0 x 10(-5) mol l-1) was found at pH 7.2 and 20 degrees C in the absence of chloride. Moreover, we show that chloride ions have an additive effect on oxygen affinity in the concentration range 10-300 mmol l-1 in the presence of 3 mmol l-1 2,3-DPG at low pH and temperature (pH < 7.4 and 20 degrees C). This feature may be of physiological importance to oxygen unloading under acidotic conditions when tissue temperature is low. Thermodynamic analysis reveal that in the presence of 3 mmol l-1 2,3-DPG and 100 mmol l-1 chloride, the Eskimo dog hemoglobin exhibits a low heat of oxygenation, which places this animal close to arctic ruminants with respect to the influence of temperature on oxygen binding in vivo.

Nitrogen microbubbles induce a disappearance of single platelets (aggregation) with porcine platelets: a comparative study of the effects of anticoagulants and blood collection methods.

The pathogenesis of decompression illness (DCI) is uncertain. DCI involves all parts of the organism where gas bubbles are produced. They have both primary and secondary effects and have been classified as an agonist aggregating human platelets. In vitro effects of N2 bubbles on porcine platelets were investigated. Comparative studies using two different anticoagulants and three different sampling methods were performed. A disappearance of single platelets interpreted as platelet aggregation was observed in the presence of N2 bubbles in all studied groups. Aggregatory responses were more profound with platelets in heparinized plasma than in citrated plasma. In citrated plasma the aggregatory responses were more profound when blood was obtained from nonanaesthetized (awake) animals than from slaugtherhouse animals. Adrenaline (1 microM) had an inhibitory effect on N2 bubble induced platelet aggregation in vitro. The pig could be useful to investigate possible gas bubble effects in vivo.