J. Gripenberg

Effects of Halothane, Thiopental, and Lidocaine on Fluidity of Synaptic Plasma Membranes and Artificial Phospholipid Membranes

The effects of halothane, thiopental, and lidocaine were studied with spin-labeling methods in synaptic plasma membranes (order parameter) and artificial phospholipid membranes (lateral diffusion). Halothane had a biphasic action, low concentrations (0.64 ran) ordering and high concentrations (2.9 ran) fluidizing both types of membranes. A biphasic effect in phospholipid membranes was also seen with thiopental, 0.1 mM ordering and 10 mM fluidizing, whereas in synaptic plasma membranes both low and high concentrations caused an increased order in the lipid bilayer region. At high thiopental concentrations, a considerable number of molecules may have reacted with membrane proteins or accumulated in the highly fluidic hydrophobic interior region of the membrane without affecting the rotational movement of the labeled fatty acid. Lidocaine alone, or together with calcium chloride, at various concentrations to 10 mM had no significant effect, and a fluidizing effect of 1 mM calcium chloride was possibly a result of interaction of calcium chloride with the label. The results indicate that the three lipid-soluble anesthetics interact differently with the lipid part of membranes. Lidocaine did not seem to affect bilayer lipids, while thiopental and halothane in phospholipid vesicles and halothane alone in synaptic membranes caused a dose-dependent biphasic effect.

Uptake of radiocalcium by nerve endings isolated from rat brain: kinetic studies.

1 The uptake of radiocalcium by nerve‐ending particles isolated from rat brain was studied in vitro by means of a rapid lanthanum quenching technique. 2 The observed uptake fits a theoretical three‐compartment model with two separate uptake phases, a fast, initial phase followed by a late, slow phase. This holds true during control conditions as well as during high‐potassium stimulation. 3 The uptake as a function of the external calcium concentration can be described in terms of Michaelis‐Menten kinetics during high‐potassium stimulation. Under control conditions the fit is clearly applicable but statistically not as good as during potassium stimulation. 4 The affinity for the uptake of calcium remains unchanged under control conditions while during high‐potassium stimulation the affinity drastically decreases during the late, slow phase of uptake. 5 During high‐potassium stimulation the maximal velocity of calcium uptake is twice that during control conditions. This holds true for both the fast and the slow phases of the uptake. 6 Mg2+ has an inhibitory effect on the uptake, the inhibition being more effective during high‐potassium stimulation. Tetrodotoxin has a slight inhibitory effect additional to that exerted by Mg2+ during the initial phase of uptake into high potassium stimulated synaptosomes.

Fine structure and enzyme histochemistry of developing duodenal epithelium of the chicken

SummaryThe histochemical activity of alkaline (AlPh) and acid phosphatases (AcPh), adenosine triphosphatase (ATPase), monoamine oxidase (MAO), succinic (SDH), isocitric (ICDH), glucose-6-phosphate (G6PDH) and lactic (LDH) dehydrogenase and leucinamino-peptidase (LAP) was studied in the duodenal wall of the chicken during pre- and postnatal growth. The morphogenesis of the developing epithelium was studied by electron microscopy.In 8-day-old embryos weak activity of all the enzymes but AlPh was observed in the cytoplasm of the epithelial cells of the mucosa. During the last third of the prenatal growing period the activity of AlPh, ATPase, MAO, SDH, ICDH, G6PDH and LAP increased strongly in the epithelium. In the adult chickens the epithelium exhibited strong activity of all the enzymes studied but LAP, the activity of which was moderate. The most intense activity of AlPh, AcPh, MAO and LAP was located in the cytoplasmic region adjacent to the bowel lumen, i. e. the microvillous and terminal web area of the epithelial cells.By electron microscopy, and inactive phase in the development of the epithelial microvilli was seen from the 10th to the 16th incubation day, followed by slow (16th–19th) and rapid (at about the time of birth) growing phases. The differentiation and the growth of the microvilli occurred at about the same time as the appearance of the enzymes in the apical cytoplasmic region of the epithelial cells. During the last third of the prenatal life the volume of the epithelial cells increased greatly, as did the number of mitochondria, lysosomes, vesicles and saccules of the Golgi apparatus. The crypt cells and the villus epithelial cells did not show similar morphological and enzymatic characteristics. The fine structure of the crypt cells resembled that of the non-differentiated embryonic epithelial cells of the duodenal mucosa.

The fluidity gradient in erythrocyte membranes in hereditary spherocytosis: a spin label study.

Summary. The fluidity gradient and sulphydryl groups in erythrocyte ghost membranes from healthy subjects and from seven patients with hereditary spherocytosis (HS) Lvere studied by spin label techniques. The mobility of the stearic acid spin labels was lower in the spherocyte membranes, indicating greater stability of the phospholipid layer in these membranes than in those of matched controls. This stabilization was most distinct in the intermediate and deep membrane layers. No clear differences were observed in the protein sulphydryl groups. It is suggested that the decreased cellular deformability characterizing spherocytes reflects altered lipid organization or lipid‐protein interaction in the interior of the cell membrane.

Evaluation of the Myotoxicity of Bupivacaine in Bier Blocks???A Biochemical and Electron Microscopic Study

The possible myotoxic effect of bupivacaine in combination with tourniquet ischemia was evaluated in 11 patients who underwent surgery of an arm under intravenous regional anesthesia. Eleven patients with the same kind of surgery and tourniquet who had general anesthesia served as controls. Venous blood bupivacaine concentrations in the anesthetized arm were high at the end of tourniquet time (27.2–202 μg/ml) and varied from 2.3 to 12.3 μg/ml 10 min after tourniquet release. Changes in blood-gas tensions and plasma potassium and lactate concentrations before and just after tourniquet release correlated with the ischemia time. Changes in creating phosphokinase, lactate dehydrogenase and aspartate aminotransferase activities, possible indices of loss of integrity of muscle cell membranes, varied considerably and did not correlate with the ischemia time. There were no significant differences between the two groups in any of the parameters. Electron microscopy revealed no evidence of muscle degeneration 24 hr after the use of tourniquet with either bupivacaine intravenous regional (n = 4) or general anesthesia (n = 3).

Uptake of radiocalcium by nerve endings isolated from rat brain: pharmacological studies.

1 The uptake of radiocalcium by nerve‐ending particles isolated from the striatum of rat brain was studied using lanthanum as a quenching agent. 2 High potassium‐induced calcium uptake occurred in two phases: an initial rapid phase and a late slow phase. Following preincubation with CaCl2 2.2 mmol/l for 1 h, dopamine at 1 to 2 × 10−4 mol/l reduced the high potassium‐induced calcium uptake which occurred during the initial rapid phase by 66 and 25% at 2 and 4 s of incubation, respectively, but had no effect on the late slow uptake phase. 3 Haloperidol at 1 × 10−6 mol/l abolished the inhibitory effect of dopamine on the initial rapid phase of the high potassium‐induced calcium uptake. Haloperidol per se had no effect on the calcium uptake. 4 Dibutyryl cyclic adenosine monophosphate at 2.5 × 10−3 mol/l or prostaglandin E1 (PGE1) at 1 × 10−5 mol/l had no effect on the initial rapid phase of the high potassium‐induced calcium uptake by striatal synaptosomes. Neither of these agents affect calcium uptake by whole brain synaptosomes. 5 It appears that in the striatum, dopamine regulates the depolarization‐induced influx of calcium in presynaptic nerve endings. This mechanism could constitute a feed‐back inhibition for transmitter release in the striatum.

Methodological studies on the uptake of radiocalcium by nerve endings isolated from rat brain

Abstract Different techniques for arresting uptake of 45 Ca by synaptosomes were compared. 1) Dilution of samples with incubation medium arrested calcium uptake but did not remove extracellularly bound calcium. 2) Dilution with medium containing 0.4 mmol 1 −1 LaCl 3 not only arrested calcium uptake but also prevented calcium efflux and, if enough time was allowed, displaced extracellular calcium. 3) Dilution with medium containing 3 mmol 1 −1 EGTA gave uptake values similar to those obtained with La 3+ , but only if extensive extraction of calcium was prevented by rapid handling of samples. Results obtained after quenching with La 3+ or EGTA showed that calcium uptake by synaptosomes may be a multiphasic process, which emphasizes the need for techniques that allow for satisfactory time resolution.

Intestinal accumulation of 111In-granulocytes in patients studied because of occult infection

Abstract111In-granulocyte scintigraphy was performed on 245 patients in whom a localized infection was suspected. In 123 patients scintigraphy was positive and of these 35 (28%) had intestinal accumulations of 111In-granulocytes. Specific local causes for the intestinal uptake of radioactivity were antibiotic associated colitis (eight patients), local pyogenic bowel infection (four patients), systemic disease (two patients), bowel necrosis (two patients), colonic cancer (one patient) and Stevens-Johnsons syndrome (one patient). Nonspecific mechanisms of bowel accumulation were desquamation of labelled granulocytes (12 patients) and bleeding (two patients). In three cases the mechanism of colonic accumulation of granulocytes was not revealed. These results show that unexpected accumulations of labelled granulocytes in the gut is not a rare phenomenon and is often due to clinically significant intestinal inflammation or other disease, especially in patients who do not have signs of respiratory, pancreatic or oesophageal inflammation causing desquamated granulocytes to accumulate in the gut.

Membrane Characteristics and Metabolic Properties of Glucose‐6‐Phosphate Dehydrogenase Deficient Red Cells

Summary. Two Finnish variants of reduced erythrocyte glucose‐dehydrogenase (G‐6‐PD) activity were studied. The G‐6‐PD Espoo variant is characterized by severe enzyme deficiency which is normally non‐haemolytic although primaquine sensitive. The other variant, G‐6‐PD Helsinki, in which the enzyme activity is moderately reduced, is associated with chronic haemolytic anaemia.