Glucose oxidation and oxygen consumption of isolated guinea pig and muskrat hearts

Glucose in Krebs-Henseleit buffer was presented to isolated Langendorff perfused muskrat and guinea pig hearts that were paced at 240 beats/min. Glucose uptake (amount removed from the perfusion fluid) was 3 times greater in the muskrat hearts than in the guinea pig heart. Glucose oxidation (amount converted to CO2) and oxygen consumption did not differ in the hearts of the two species. When glucose is the only exogenous substrate, isolated muskrat hearts extract more glucose than guinea pig hearts but oxidize similar amounts of glucose and have a similar myocardial oxygen consumption.     

Effect of normobaric oxygen treatment on oxidative stress and enzyme activities in guinea pig heart

Normobaric oxygen (NBO) therapy is commonly applied for the treatment of various diseases, including myocardial infarctions, but its effectiveness is controversial. Potential adverse effects of hyperoxia are related to excessive formation of free radicals. In the present study we examined the effect of 60-h NBO treatment on lipid peroxidation (LPO), activity of manganese superoxide dismutase (Mn-SOD) and mitochondrial enzymes of energy metabolism in guinea pig heart. NBO treatment resulted in significant accumulation of thiobarbituric acid reactive substances and loss of Mn-SOD activity despite slight elevation of Mn-SOD protein content. Activity of electron transport chain complex III decreased significantly, while activity of complex IV was slightly elevated and citrate synthase was unchanged. LPO, inhibition of Mn-SOD and complex III activities were more pronounced when inhaled oxygen was partially enriched with superoxide radical. In contrast, when O(2) was enriched with oxygen cation (O(2)●+), LPO and loss of Mn-SOD activity were prevented. Complex III activity in the O(2)●+-treated group remained depressed but activities of complex IV and citrate synthase were elevated. These data suggest that NBO treatment is associated with myocardial oxidative damage and attenuation of antioxidant defense, but these adverse effects can be partially attenuated by inhalation of O(2) enriched with oxygen cation.     

Interrelationship between oxygen consumption,superoxide anion and hydrogen peroxide formation in phagocytosing guinea pig polymorphonuclear leucocytes

The paper presents an experimental procedure for a simultaneous assay of oxygen consumption, O2- release and H2O2 accumulation at a very early stage of the respiratory burst that is induced by phagocytosis in guinea pig polymorphonuclear leucocytes. The main findings are as follows: (a) The oxygen consumption that is measurable does not correspond to all oxygen that is reduced. The relationship between the actual oxygen consumed and the amount that is reduced depends on the fate of the intermediate products O2- and H2O2. (b) O2- is measurable extracellularly by the reduction of cytochrome c. When cytochrome c oxidizes the extracellular O2-, molecular oxygen is formed. This fact is shown by a decrease of oxygen consumption. The molar ratio between the O2- detected and the oxygen given back is 1. (c) The amount of O2- released from the cells accounts for only a small part of oxygen actually reduced. (d) H2O2 is detectable only in the presence of NaN3. In this condition almost all oxygen consumed is recovered in the form of H2O2. The molar ratio O2/H2O2 is near unity. The amount of H2O2 derived from dismutation of O2- released is only an aliquot of the total H2O2 accumulated. Thus, most of H2O2 is derived from intracellular sources. (e) In the absence of inhibitors of H2O2 degrading reactions, no detectable accumulation of peroxide occurs. Under these conditions, the main part of H2O2 formed is degraded in almost equal amount by catalase and myeloperoxidase, while only a small aliquot is degraded by NaN3 insensitive reactions.     

Comparative studies on the adhesiveness of granulocytes of guinea pig and man

Summary The high affinity of granulocytes of guinea pig and man to glass surfaces is modified by serum. Native serum contains both an adherence-promoting activity, which is related to complement, and components which reduce the adhesiveness of granulocytes. These components are stable at 56°C for 30 min and are tightly bound to the glass surface. -Lipoproteins are candidates for this adherence reducing ability of serum. Adherence promotion by native serum is mediated by coating the glass surface with C3b/C3bi. Human granulocytes from the peripheral blood adhered to glass surfaces coated by native human or guinea pig serum with C3b/C3bi to almost the same extent as in the presence of native serum, but on guinea pig granulocytes elicited in the peritoneal cavity, a cell surface metalloproteinase degraded the C3b/C3bi, thus reducing the adhesiveness of these cells. This proteinase was inhibited by MgEDTA, DTT, and 1,10-phenanthroline, whereby the high adhesiveness of granulocytes was restored to C3b/C3bi-coated glass.Abbreviations BA benzamidine hydrochloride - BTS Bacillus thuringiensis subtoxicus - DTT dithiothreitol - EAC -amino-caproic acid - gp guinea pig - LDL low density lipoproteins - SEM scanning electron microscopy     

Blood circulation and oxygen transport in the fetal guinea pig

Anaesthetized fetal guinea pigs near term were studied under conditions, where maternal placental flow of haemoglobin was maintained within the normal range. The rate of maternal fetal equilibration of intravenously injected 3H2O was found to be similar as in unanaesthetized animals (half time 4 min) indicating that fetal circulation was undisturbed under the present experimental conditions. Umbilical blood flow as determined by a modified 3H2O method was 0.13 ml . min-1 . g-1 of fetal body mass. Radioactive microspheres, injected into the fetal saphenous (jugular) vein, were distributed to the placenta, the lower body, the upper body and the lungs at a ratio of 31(47):27(39):30(6):12(8). From these data, cardiac output was calculated (0.38 ml . min-1 . g-1) and found to be almost equally distributed between the placenta, the lower body and the upper body. There was preferential streaming of the inferior vena caval blood to the upper body. There was no evidence for flow through a ductus venosus. The O2-saturation in the fetal carotid arterial blood was 59 +/- 4%. The O2-supply to the fetal tissues was estimated to be 3 times the oxygen consumption.     

Semicircular duct and ampulla dimensions in cat,guinea pig and man

Predictions from the classic theory of semicircular canal operation, the torsion pendulum model, depend upon labyrinthine dimensions and the physical properties of the endolymph. The dimensions of the semicircular canal, duct and ampulla in cat, guinea pig and man were determined from measurements of magnified sections of decalcified temporal bones. Estimates of the effect of shrinkage were obtained from measures in fresh material and it appears shrinkage is probably only a fairly small factor. The dimensions so obtained were used to provide new estimates of the short time constant and other mechanical parameters of the torsion pendulum model in the three species.