Atypical Langmuir adsorption of inhalation anesthetics on phospholipid monolayer at various compressional states: difference between alkane-type and ether-type anesthetics

Adsorption of chloroform, halothane, enflurane and diethyl ether on the air/water interface was compared with adsorption on the dipalmitoylphosphatidylcholine monolayer, spread on the air/water interface, at four compressional states; 88.5, 77.0, 66.5 and 50.5 A2 surface area per phosphatidylcholine molecule. Anesthetics were administered from the gas phase. The affinities of these agents to the phosphatidylcholine monolayer varied according to the state of the monolayer. Chloroform and halothane showed a stronger affinity to the highly compressed phosphatidylcholine monolayer (50.5 A2) than to the expanded monolayer (88.5 A2) or to the air/water interface without the monolayer. Diethyl ether behaved in reverse; a stronger affinity to the expanded monolayer was exhibited than to the compressed monolayer. Enflurane showed the highest affinity to the intermediately compressed monolayer (77.0 A2). The adsorption isotherm of anesthetics to the monolayer was characterized by atypical Langmuir-type, in which available number of binding sites changed when anesthetics were adsorbed. The mode of adsorption onto the monolayer was dissimilar to adsorption onto air/water interface, where adsorption followed the Gibbs surface excess. A theory is presented to explain the above differences. The adsorbed anesthetic molecules do not stick to phosphatidylcholine molecules but penetrate into the monolayer lattice and occupy the phosphatidylcholine sites at the interface. Quantitative agreement between the theory and the experimental data was excellent. For the monolayer at 50.5 A2 compression, the changes in the transfer free energy accompanying the anesthetic adsorption from the gas phase to the monolayer were in the order of chloroform greater than halothane greater than enflurane greater than diethyl ether, in agreement with the clinical potencies.     

Stopped-flow rapid kinetics of anesthetic-induced phase transition in phospholipid vesicle membranes: nonlocalized fluctuation

Kinetics of the gel to liquid-crystalline phase transition of dipalmitoylphosphatidylcholine vesicle membrane was studied by the stopped-flow technique with turbidity detection. The observed change in turbidity was well characterized by a single-exponential decay curve with relaxation time in the millisecond range, although the existence of a faster process than the dead-time of the stopped-flow apparatus was inferred from the amplitude analysis. Relaxation times were determined as functions of 1-hexanol concentration and temperature just below phase transition. From the analysis based on the theories of nonequilibrium relaxation, it is concluded that the phase transition induced by 1-hexanol is governed by a nonlocalized fluctuation mechanism. The anesthetic-induced nonequilibrium state is unstable rather than metastable.     

Immunohistochemical studies of the serotonergic supraependymal plexus in the mammalian ventricular system, with special reference to the characteristic reticular ramification

Distributional and morphological features, especially characteristics of the ramification of serotonin-containing supraependymal fibers (SEF), were studied in the ventricular systems of mammals (mouse, rat, guinea pig, rabbit, cat, dog, monkey) by means of a modified peroxidase antiperoxidase technique, using antiserotonin antiserum prepared in our laboratory. SEF were present in all ventricular systems, except on the third ventricle floor and in the choroid plexus. The density of SEF was higher in the smaller species. In the rat, light- and scanning electron microscopical SEF were almost completely abolished 1 week after intraventricular administration of 5,6-dihydroxytryptamine. Ramification of SEF was complicated; the SEF formed a true network with frequent anastomosing. In the ventricular system of rats rendered hydrocephalic by kaolin administration, the mode of axonal branching in the supraependymal plexus could best be analyzed by the scanning electron microscope because the meshes of the plexus were spread out.     

Studies on the ontogenesis and the regulatory mechanisms of placental lactogen and insulin binding sites (receptor) in rat liver

The ontogenesis of specific binding of 125I-hPL and 125I-insulin was determined in rat liver cell membranes (10(5) X g pellets), and the regulatory mechanisms of these binding sites were also examined. There were striking differences in the mode of ontogenesis between binding sites of hPL and insulin in rats. HPL binding sites were very few in liver cell membranes from fetal and immature rats. They began to increase after puberty, and markedly increased in late pregnancy. On the other hand, insulin binding sites, which decreased in late pregnancy, were dominant in fetal liver and placenta. Consequently, the lipolytic and glycogenolytic activities of hPL in maternal liver were accentuated, whereas the effects of insulin on maternal liver were suppressed. In contrast, in fetal liver and placenta only the anabolic effects of insulin seemed conspicuous. According to the results of experiments on in vivo administration of estradiol-17 beta, progesterone, hydrocortisone or hPL to intact or hypox-rats, and the measurement of serum rat chorionic mammotropin (rCM), rPRL, estradiol-17 beta, and insulin during pregnancy in rats, the increase in hepatic hPL binding sites observed in late pregnancy might be, at least in part, due to rCM secreted from placenta, and the decrease in insulin binding sites due to the increase in serum insulin itself in rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Subcellular distributions of calcium/calmodulin-stimulated and guanine nucleotide-regulated adenylate cyclase activities in the cerebral cortex

The subcellular distribution of Ca²⁺/calmodulin-stimulated adenylate cyclase activity was studied in comparison with that of guanine nucleotide-stimulated cyclase activity. The distributions of these activities were similar among the crude fractions but differed among the purified subsynaptosomal fractions. The specific activity of Ca²⁺/calmodulin-stimulated cyclase was highest in a light synaptic membrane fraction, which has few, if any, postsynaptic densities, whereas that of guanine nucleotide-stimulated cyclase was highest in a heavier synaptic membrane fraction rich in postsynaptic densities. These results suggest that the Ca²⁺/calmodulin-stimulated cyclase has, at least in part, a different cellular or subcellular location than the guanine nucleotide-stimulated cyclase.Abbreviations used CaM calmodulin - GppNHp guanosine 5-(,-imino) triphosphate     

Vascular systems in the magnoliaceae

Journal of Plant Research - The vascular anatomy of seven genera of Magnoliaceae:Elmerrillia, Liriodendron, Magnolia, Manglietia, Michelia, Paramichelia andTalauma, was examined. Based on the...     

Haemolysis of rabbit erythrocytes by a lectin from the seeds of<Emphasis Type="Italic">Croton tiglium</Emphasis>

The kinetics of haemolysis of rabbit erythrocytes byCroton tiglium lectin was studied as a function of concentration of the lectin and erythrocytes. The length of the prelytic period decreased with increasing lectin concentrations, indicating that the secondary events at the membrane which follow the binding of the lectin to cell surface carbohydrate receptors are accelerated at higher surface concentrations of the lectin. The rate or extent of haemolysis was not affected by the inclusion of ions like K⁺, Ca²⁺ and Mg²⁺ in the medium or by the substitution of ionic medium by a non-ionic medium. The inhibition of haemagglutination and haemolysis of rabbit red cells byCroton tiglium lectin by antilectin rabbit serum was observed. A possible mechanism of haemolysis by the lectin is discussed.