Growth Hormone Deficiency Impairs Blood Clotting and Reduces Factor VII Coagulant Activity in Rat

To investigate pituitary effects on the vitamin K-dependent coagulation factors, female rats were hypophysectomized (hypox) and treated with growth hormone (GH), cortisone, thyroxine, vitamin K, or saline. After 11 days of treatment, the prothrombin time, platelet count, and factors II, VII, IX, and X were determined. The prothrombin time was 52.9 ± 1.2% for control rats and 39.1 ± 0.8% for hypox rats (mean ± SEM; p<0.001). All factors decreased after hypophysectomy, reaching significance for factor VII (from 264 ± 23% to 131 ± 9%; p <0.001) and factor IX (from 28.4 ± 2.2% to 17.1 ± 2.5%; p<0.01) while the platelet count was unaffected. When hypox rats were treated with GH, the prothrombin time increased to 50.9 ± 1.0% (p <0.001) and factor VII to 299 ± 10% (p<0.001). Factor II, IX, and X were slightly increased after GH substitution but not after cortisone, thyroxine, or vitamin K treatment. To summarize, GH is of importance for normal hemostasis in the female rat.

Influence of pericardial suction blood retransfusion on memory function and release of protein S100B

Background: To study the influence of pericardial suction blood (PSB) on postoperative memory disturbances and release patterns of protein S100B during and after cardiopulmonary bypass (CPB).

Methods: Sixty male patients admitted for coronary artery bypass surgery were prospectively randomized to receive PSB either by using conventional cardiotomy suction retransfusion or after cell-saver processing.

Results: The concentration of S100B rose during the period of CPB from 0.065±0.004 to 0.24±0.001 mg/L (p<0.001). PSB contained 18.0±1.7 mg/L of S100B. Direct retransfusion from the cardiotomy reservoir made the systemic level increase to 1.42±0.19 mg/L compared to 0.25±0.02 mg/L using a cell-saver. Signs of postoperative memory dysfunction (> 1 SD) were discovered in one of three tests, but were unrelated to technique of retransfusion. No associations were found between serum concentrations of S100B and memory function.

Conclusion: In this study, retransfusion of PSB during cardiac surgery appeared not to cause memory disturbances. PSB contained high concentrations of protein S100B making its use as a marker of cerebral injury unsuitable.

Endogenous gas formation of carbon dioxide used for wound flooding--an experimental study with implications regarding gas microembolism during cardiopulmonary bypass

BACKGROUND

Gas microembolisation is an identified risk in cardiac surgery. Flooding the wound with carbon dioxide is a method proposed to reduce this problem. The high solubility of carbon dioxide is beneficial, but may also cause problems. The gas solubility diminishes at warming and endogenous bubbles are formed when cold blood saturated with carbon dioxide is returned by cardiotomy suction.

METHODS

The release of endogenous gas was measured at high resolution in an experimental digital model. A medium (water or blood) was incubated and equilibrated with gas (100% carbon dioxide or air) at a low temperature (10 °C or 23 °C). The temperature was increased to 37 °C and the gas release was measured, at rest and at fluid motion.

RESULTS

The amount of carbon dioxide released at warming was substantial for both water and blood (both p=0.005). The effect was more pronounced when the temperature differential increased (p=0.005). However, blood and water differed in these terms: with water, the release of carbon-dioxide started instantly at warming; with blood, carbon dioxide remained dissolved and was released at fluid motion. When blood was warmed from 10 °C to 37 °C, the gas release corresponded to 44.4% (40.6/46.5) of the medium volume (median with quartile range).

CONCLUSION

Gas dissolved in a medium becomes released at warming, as confirmed here. Blood exposed to carbon dioxide became heavily oversaturated at warming, with the gas instantly released at fluid motion. The amount of contained gas increased with a higher temperature differential. Our study has relevance to wound flushing, using carbon dioxide, in cardiac surgery. The clinical consequences of these findings remain to be answered.

Inflammatory mediators in autotransfusion drain blood after knee arthroplasty, with and without leucocyte reduction

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate whether leucocyte-reducing filters influenced complement activation and the formation of pro-inflammatory cytokines in autotransfusion drain blood after knee arthroplasty.

MATERIALS AND METHODS

Twenty-three patients undergoing knee arthroplasty were divided into two groups. All patients were given salvage blood postoperatively. In Group A, a leucocyte filter was connected between the wound and the drain blood container. In Group B the drain blood was not leucocyte filtered. Complement split products and cytokines were analysed in circulating blood and in drain blood, together with blood-cellular differential counts.

RESULTS

Drain blood showed activation vs. venous blood, with elevated concentrations of C3a, SC5b-9, interleukin (IL)-6, IL-8, polymorphonuclear (PMN) elastase and tumour necrosis factor-alpha (TNF-alpha) (P<0.05 to P<0.001). The leucocyte filter reduced TNF-alpha (P<0.01), but triggered complement activation (P<0.05). Room-temperature incubation increased the concentration of IL-8 (P<0.01), which was seen in both venous and drain blood. The leucocyte filter prevented formation of IL-8 (P<0.01). In drain blood at 24 h the inflammatory reactions accelerated (P<0.05-0.001), although the filter reduced the leucocyte counts and TNF-alpha concentrations.

CONCLUSIONS

The leucocyte filter reduced IL-8 and TNF-alpha in drain blood, but at the same time triggered complement activation. Incubation affected the inflammatory spectrum of both drain blood and control venous blood, and the filtering reduced this activation.

Theoretical and experimental aspects of erythrocyte filterability testing; flow acceleration and systemic resistance

Blood cell filterability is an established method in blood rheology. The dynamics at flow onset and its relevance to the data interpretation is, however, not fully known. This paper aims to investigate what controls the length and slope of flow acceleration as the medium accelerates to reach the steady state, and how this phenomenon may interfere with the data output. The acceleration time was not constant. With buffer the steady-state flow showed a logarithmic correlation (p<0.05) versus acceleration time and a linear correlation (p<0.001) versus acceleration slope. With 5% erythrocyte resuspension the steady-state flow instead demonstrated a linear relationship versus acceleration time (p<0.001) and no correlation versus acceleration slope. A cut-off timing of 0.6s is suggested to avoid artifacts associated with flow acceleration. The possible influence on data interpretation from the flow channel systemic resistance was also addressed, and found to significantly underestimate measurable changes in erythrocyte properties from unprocessed flow curves. This was despite the traditional correction for blank filtration flow. Both acceleration and effects from systemic resistance do probably have minor influence on the historic data interpretation but could perhaps be considered in the methodology to sharpen the data output.

Impaired contractility of left-over vein grafts used for CABG and the possible trauma caused by air exposure

OBJECTIVE

The patency of vein grafts limits the long-term results after bypass surgery. Vein graft trauma may contribute to the clinical results.

DESIGN

Left-over pieces of vein after routine coronary bypass surgery were compared with references of the same vein that were stored with maximum care. Blood perfusion (20 h, 37 degrees C) was also tested to evaluate possible recovery. Vessel rings were measured by isometric tone recordings.

RESULTS

Left-over veins showed a contractile dysfunction compared to reference (p < 0.01-0.001, n = 13), and that did not recover after blood perfusion. Four trauma models were tested, using saphenous vein graft (SVG)-references (n = 5). Chemical exposures (0-90 min) to NaCl-papaverin or cardioplegic medium affected the baseline (p < 0.05-0.01). With mechanical distension, up to 450 mmHg leak testing, an increased norepinephrine (NE) reactivity appeared. Air contact, 20 min, reduced the NE reactivity to half maximum (p < 0.05). Longer exposures (40-60 min) completely abolished the contractility.

CONCLUSIONS

The saphenous vein smooth muscle function appeared permanently traumatized following routine harvesting and handling. Air exposure gave dramatic deterioration and could in theory contribute to hamper the long-term results after bypass surgery.

D-glucose additive protects against osmotic-induced decrease in erythrocyte filterability

Glucose has long-term effects on erythrocyte filterability owing to sorbitol accumulation and glycosylation of intracellular proteins, but glucose effects prior to these long-term metabolic consequences have not been studied to the same extent. D-glucose is osmotically inert in erythrocytes because of facilitated diffusion. Erythrocyte volume regulation, hemolysis and filterability were studied with reference to effects of glucose derivatives dissolved in water. Control situations were water alone or buffer. Salt-stock dilution by water, D-glucose, or 3-O-M-glucose in water (both 570 mmol/L additives) created volume increases of 4.0 +/- 0.2%, 3.4 +/- 0.5% and 3.3 +/- 0.2%, respectively, whereas L-glucose resulted in a 2.2 +/- 0.4% volume decrease (all p < 0.001 versus baseline, mean values +/- SEM). D-glucose at a final concentration 30 mmol/L did not display any osmotic properties. Despite erythrocyte swelling, electrolyte-free glucose did not induce any significant changes in filterability with either 3-microm or 5-microm filters. 3-O-M-glucose gave a 7.8 +/- 1.4% decrease in 3-microm filterability (mean value +/- SEM, p < 0.001), but not to the same extent as by water alone at the corresponding dilution rate (31.7 +/- 3.5%, mean value +/- SEM, p < 0.001). L-glucose caused a 2.0 +/- 0.8% decrease in filterability across the 5-microm (mean value +/- SEM, p < 0.05), but not with the 3-microm filters. Stressing the glucose transport system further, to simulate the water-like properties of electrolyte-free glucose during intravenous infusion, we found that glucose becomes osmotically active and prevents hemolysis at these extreme concentrations (> 114 mmol/L). We conclude that an in vivo concentration range of D-glucose protects the erythrocytes from a decreased filterability induced by osmotic swelling but without having any osmotic properties.

Narrow-pore flow behavior of blood cells in cardioplegic suspension

Cardioplegia alters the ionic composition of the myocardium and also the blood in a way that may influence the cellular capillary flow behavior. We measured changes in RBC volume and narrow-pore flow resistance of blood cardioplegia versus crystalloid medium. Potassium, magnesium and sodium as osmotic control caused an expected cell shrinkage and reduced the flow resistance through 3 microm pores; however, stressing the osmosis further resulted in increased resistance. No major effects were seen with the 5 microm filters. Twenty percent blood cells in the cardioplegic medium caused a 360% increase in 5 microm pore resistance. There were no obvious additional filterability effects of the cardioplegic additives other than their osmotic patterns. There may be a theoretical advantage in having a cell-free medium in terms of flow resistance. Using blood cardioplegia, a limited hypertonicity may be beneficial in reducing the capillary flow resistance of RBC.

Response in shape and size of individual p31 cancer cells to cisplatin and ouabain: a computerized image analysis of cell halo characteristics during continuous perfusion

BACKGROUND

Volume regulation is essential for cellular functions, including cell death, such as apoptosis. Flow cytometry is standard for nonadherent cells, such as blood cells. Our aim was to explore image analysis methods to study adherent cancer cells of a solid tumor.

METHODS

P31 mesothelioma cells were perifused (40 min) and studied by phase-contrast microscopy. A noise reduction of the cell contour was tested to more accurately yield the cell shape factor (SF). The optical halo around the cell was analyzed for information about membrane blebbing.

RESULTS

The projected cell area (PCA) slowly increased under control perfusion, the halo outside more than the halo inside. Cisplatin (apoptosis) caused an immediate increase in the PCA-halo outside (5.9 +/- 1.2 %, P < 0.01, 1-5 min) and the SF indicated decreased roundness (P < 0.05). The SF-halo inside became more irregular than the outside, which was different from the control cells. The morphology reflected instant blebbing, and the cell bodies showed fragmentation after about 20 min. Ouabain resulted in only small changes in PCA and SF, significantly different from both control and cisplatin conditions.

CONCLUSIONS

Image analysis (PCA and SF) on perifused adherent cancer cells may serve as a tool to follow the sensitivity of cancer chemotherapy and to study cell death patterns.

Red blood cell trauma during cardiopulmonary bypass: narrow pore filterability versus free haemoglobin

Ten patients admitted for coronary artery bypass grafting were investigated with respect to the influence of cardiopulmonary bypass (CPB) on red blood cell (RBC) trauma. Blood samples were collected prior to, at the start of, and at 30 and 60 min of CPB. RBC deformability was assessed by filtering re-suspended RBCs through a polycarbonate membrane using a computer-controlled filtrometer. Multiple regression analysis was employed to evaluate RBC flow-curve characteristics denoted by the initial filtration rate (IFR) and clogging slope (CS). Release of free haemoglobin was determined concomitantly. IFR was estimated at 90.39 microl/s and CS at -5.32 microl/s2 prior to CPB. During 60 min of CPB, neither IFR nor CS deviated significantly (p > 0.05) from these reference values. However, release of free haemoglobin increased significantly (p < 0.018) from the start of CPB to the 60-min determination. In conclusion, 60 min of CPB seems not to alter significantly RBC deformability in a 5 microm pore filtration model, despite a significant release of haemoglobin.

Microrheology of filtered autotransfusion drain blood with and without leukocyte reduction

Autotransfusion of filtered knee drain blood (FKDB) is frequently practised in orthopaedic surgery, but questioned because it contains inflammatory cytokines, contaminants from lysed blood cells, debris and chemicals from the wound. We have studied the microrheology (5 microm pore filtration) of FKDB (n = 23) with versus without the addition of a leukocyte reducing filter (LRF) in line with the drain. As expected the whole blood clogging was reduced (p < 0.01) due to the lowered leukocyte number by the LRF. FKDB plasma contains clogging particles of unknown origin. With the LRF the increased plasma clogging was reduced (p approximately 0.05). With resuspended erythrocytes there was an increase in clogging rate in FKDB at 24 hours. This increase was abolished with the addition of the LRF, which may indicate that the erythrocyte trauma results from the incubation together with leukocytes in the drain container. There is a potential for further improvement of the filters in autotransfusion drains.

Serotoninergic modulation of cell volume response to estramustine: an image-analysis study on perifused individual glioma cells

A technique of microscopy with computerised detection of early morphological changes during continuous perifusion was used to monitor the geometry changes of cultured glioma cells (MG-251) when exposed to 40 mg/L estramustine phosphate (EMP) alone or in combination with granisetron (0.1 mumol/L), ondansetron (0.1 mumol/L), or serotonin (1 mumol/L). When the cells were exposed to EMP, cell volume measured as projected cell area (PCA) rapidly increased. Serotonin and ondansetron, but not granisetron, prevented the acute EMP response (PCA). Serotonin, but none of the 5-HT3 receptor antagonists, protected against the cytotoxicity of EMP to the glioma cells as measured by a fluorometric microculture assay. Our results demonstrate hitherto unknown differences between selective 5-HT3 receptor antagonist on the cellular response to EMP and shows the necessity to study the receptor antagonists from viewpoint of interference with the antitumour drug effects on malignant cells. The perifusion technique could be used to study the effects of serotoninergic agonists and antagonists on cell volume regulation of cells exposed to anticancer drugs.

Filterability of autotransfusion blood cells and plasma after total knee arthroplasty

Postoperatively filtered drain blood can be used for autotransfusion, but quality has been questioned. The blood contains activated or destroyed blood cells, debris, and chemicals from the wound. The ConstaVac autotransfusion system was used in 18 patients operated with a total knee prosthesis. Samples were taken from drain blood and compared with venous blood at different sampling times (to 24 h) and different incubation conditions. Micro-rheology was measured as pore filterability (5 microm) in whole blood, erythrocyte resuspension, and plasma. The filtration flow resistance was significantly lower in drain whole blood, but was unchanged in erythrocyte resuspension compared to venous blood. However, the rate of filter clogging was unchanged in drain whole blood, but was increased in the erythrocyte resuspension at 2 h. Drain plasma filterability indicated particle contamination. In total, the filterability of resuspended drain erythrocytes and cell-free plasma is affected, but this is not significant enough to have effects on drain whole blood filterability which is increased, possibly due to the leukocyte reduction. From these perspectives, we consider drain blood acceptable for autotransfusion.

Treatment of myeloproliferative disorders with hydroxyurea: effects on red blood cell geometry and deformability

Hydroxyurea (HU) is used in suppressing the bone marrow and producing fetal-like red blood cells (RBCs). These RBCs are large in size and may theoretically disturb the microcirculation. In five patients with myeloproliferative disorders (MPD), the RBC geometry and deformability were analyzed before and after 6 to 8 months of HU treatment. In untreated MPD, the RBC geometry and filterability was normal. After HU, the RBC membrane area increased 24% and the cell volume increased 39% (P <.005). This change resulted in a 12% increase in the minimum cylindrical diameter (MCD). From a static bending model of initial deformation, the RBC diametrical cross-section had a significantly increased section modulus. However, this increase in profile stiffness was compensated for by its larger projected cell area and, thus, pressure load on the RBC corpuscle. The resulting resistance to initial deformation therefore remained unchanged after HU. These findings were tested experimentally; with 3-microm filter membranes, HU treatment caused a significant increase in flow resistance (P <.02), in accordance with MCD. However, with 5-microm pores, no difference was seen, again in consonance with the theoretical findings of initial deformation. Because most capillaries are larger than 3 microm, we suggest that HU is acceptable from a perspective of cellular microrheology.

Use of polyester leukocyte elimination filters in blood filterability research

We tested a new routine to eliminate leukocytes for blood rheology measurements using commercial leukocyte absorbing filters (here PALL RC400). These filters were punched out and fitted in smaller chambers through which blood was filtered under controlled suction pressure (< 30 mm Hg). This technique resulted in a very effective leukocyte elimination to 0.0022% but also a platelet reduction to 0.2%. The process causes a small but significant hemolysis with free hemoglobin, of the order of 0.06% of the filtered erythrocytes. A small fraction of the erythrocytes were retained in the filter, versus plasma, to reduce the hematocrit on the order of 1.4%. The leukocyte filtration did not cause any detectable functional trauma to the erythrocytes, measured as micro-pore filterability of normal and glutaraldehyde (GA) hardened erythrocytes. However, when 10% of the erythrocytes were hardened with GA, which caused an increase in pore clogging slope (p < 0.05), the additional passage through the leukocyte elimination filter removed this measured change in clogging. This observation suggests that the leukocyte elimination filter may selectively remove, not only leukocytes and platelets, but also hardened erythrocytes. Reticulocyte counting did not reveal any selective removal of young erythrocytes. In general, we find the presented method reproducible, efficient and easy for eliminating leukocytes for blood rheology research although the risk of removing undeformable erythrocytes must be considered.

Autotransfusion after total knee arthroplasty. Effects on blood cells, plasma chemistry, and whole blood rheology

Postoperative drain blood was collected and reinfused using the ConstaVac system (Stryker, Kalamazoo, MI) in 30 patients after total knee arthroplasty. Of the total 1.1-L volume of postoperative bleeding, 60% was reinfused. No clinical complications were observed. Differences between venous blood and drain blood and between venous blood and drain blood after separate incubation were studied with respect to acidic and inflammatory effects on blood cells, plasma chemistry, and whole blood rheology. In drain blood, leukocyte and platelet counts were reduced (P < .001), probably as a result of consumption in the wound. Acidic incubation occurs in the drain container because of production of lactate from glucose, with a minimum pH at 5 hours of 7.2. The low pH caused slight but significant erythrocyte swelling (P < .01). The complement C3d indicated leukocyte activation, although of modest magnitude. Despite incubation and complement activation, maximum erythrocyte hemolysis after 24 hours of incubation was less than 1%. Drain blood showed a lower resistance against micropore filtration than venous blood (P < .001), mainly because of the reduced number of leukocytes, and remained unchanged with incubation. Although the autotransfusion system can be improved with respect to blood quality, filtered drain blood should be considered acceptable for reinfusion.

Combined use of micropipette aspiration and perifusion for studying red blood cell volume regulation

We combined micropipette aspiration with a new technique of perifusion to study volume behavior of single red blood cells (RBCs) during anisotonic conditions. Other techniques have suggested that RBC volume changes are complete within 1 s, but our pipette data indicate a slower volume response of 5-10 s. This difference appears to be due to the partial aspiration of the cell into the pipette, which in part prevents exposure of the membrane area to the anisotonic medium. However, we found that medium will pass the aspirated RBC (-20 mm H2O aspiration pressure) and enter the pipette at a volume rate of 0.3 micron3/s; this rate was measured by introducing a flow marker, a separate RBC or a cell fragment, into the pipette. The osmotic balance across the RBC also affected the flow: if the outside fluid was made hypertonic, the pipette flow decreased, but a hypotonic conditions, the flow increased and contributed to the exposure of the aspirated portions of the RBC. However, after the initial 10 s, the RBC geometry can be precisely monitored; at 200 mOsm, the RBC swelled by 41.0 +/- 0.9% and then demonstrated a small but significant (P < 0.001) regulatory volume decrease. We suggest that this technique is very precise in measuring the dynamics of geometric regulation, although acute changes are affected by the partial cell aspiration and pipette flow.

Computerized detection of morphological changes to glioma cells during estramustine and ion-channel blocker perifusion

A perifusion technique for microscopy with computerized detection of early changes in cell morphology during continuous perifusion was used to show that the geometry of cultured glioma cells (MG-251) changes rapidly when they are exposed to estramustine phosphate (EMP). When the cells were exposed to 20 or 40 mg l(-1) EMP, cell volume projected cell area (PCA) rapidly increased. When the Na+,K+-ATPase blocker ouabain (100 micromol l(-1)) was added to the EMP (40 mg l(-1)) perifusion, the acute EMP response was eradicated. When the PCA curve for ouabain alone was subtracted from the curve of combined ouabain and EMP perifusion, the resulting curve showed that ouabain completely blocked the EMP-induced increase in PCA. When the Na+, K+, Cl- co-transport inhibitors bumetanide (10 micromol l(-1)), or furosemide (100 micromol l(-1)), were added to EMP (40 mg l(-1)), the acute increase in PCA seen for EMP alone was also completely blocked. This study shows that inhibitors of ion transmembrane transport can modify EMP-induced cell volume increases. This may be of particular importance since the blockers have been found to interfere also with the cytotoxic function of EMP during cell culture. Thus, it is possible that cell volume changes could serve as a rapid technique for predicting the cytotoxic activity of antineoplastic drugs.

Analysis of flow acceleration during erythrocyte filtration: dependence of hematocrit and cell rigidity

At flow onset the blood filtration rate accelerates to a steady state, this may affect the interpretation of red blood cell (RBC) filterability. We studied the acceleration of flow while the pressure is built up across the filter to analyse effects of various hematocrits and RBC rigidity by glutaraldehyde (GA) hardening. This was analysed by a new filtration system with high time resolution and unlimited filtration volume. The system uses a digital balance that samples the accumulated weight (e.g., filtration rate through 5 microns Nucleopore membranes) with on-line computer communication. The filtration is computer controlled via a pneumatic valve. White blood cells (WBC) were removed prior to filtration by a WBC-eliminating filter to avoid clogging artifacts. When flow is initiated a steady state is reached at 0.3-0.4 s. This timing was also tested and confirmed by a video monitoring technique of filtration flow into a horizontal pipette. The digital balance has a mathematical function to reduce the effects of vibration noise; when this function was activated the apparent acceleration was retarded to 1.2 s. With any of these techniques the steady state timing did not vary with the hematocrit, however, the volume of filtered suspension during acceleration varied with both the hematocrit and the GA hardening (p < 0.001). Extrapolation to yield the initial filtration rate from the relative flow curve (RBC suspension divided by buffer flow) varied depending on if the acceleration phase was included or not. In the most unfavourable situation, with GA-hardened RBC, this difference was 340% (p < 0.01). The slope to calculate clogging rate was affected in a similar way. Moreover, with the most GA-hardened RBC a delay in flow onset was observed with this technique. The acceleration phenomenon may cause artifacts in systems employing volume-derived filtration kinetics because of fixed volumes of filtrated medium.

Thiocyanate induces vasoconstriction in rat-tail artery primed with norepinephrine

The vasoregulating effects of thiocyanate (SCN-) were studied by means of a new rat tail artery perfusion model that uses constant driving pressure (1000 mm H2O). When a 30 mm long artery was perfused with 20 micromol/L verapamil, the flow rate increased 6%. Norepinephrine (10 to 1000 nmol/L) caused a dose-dependent flow inhibition. SCN- alone (0.05 to 5 mmol/L) had a slight, if any, effect on the arterial flow. However, when the artery was pretreated with norepinephrine (1000 nmol/L) for 10 minutes, followed by a basal-medium washout that left a 13% norepinephrine-induced flow inhibition, 0.05 to 5 mmol/L SCN- caused a marked flow rate reduction of between 20.4% +/- 9.8% and 28.0% +/- 21.8%, as calculated for the entire test perfusion. The decrease in flow rate correlated with the SCN- concentration (p < 0.05) and showed a clear reversibility. A similar SCN(-)-induced (0.05 mmol/L) vasoconstriction (p < 0.05) was seen when the artery was given a basal tone by continuous perfusion with low-dose norepinephrine, 10 nmol/L. Nifedipine (100 nmol/L) abolished the effect of 0.05 mmol/L SCN- but did not affect the norepinephrine priming. We conclude that SCN- amplifies the norepinephrine-induced vascular smooth muscle tone and that this may be caused by an altered calcium channel activity.

Effects of pressure on red blood cell geometry during micropipette aspiration

Micropipette aspiration is a potentially useful and accurate technique to measure red blood cell (RBC) geometry. Individual RBCs are partially aspirated and from the resulting sphere diameter, total cell length, and pipette diameter, membrane area and cell volume can be calculated. In this study we have focused on possible shape artifacts associated with the aspirated portion of RBC. We observed that the apparent RBC geometry (calculated area and volume) changed markedly (P < 0.001) with the applied aspiration pressure; for normal human RBC the area increased by 5.6 +/- 0.6% and volume decreased by 4.7 +/- 0.6% when the aspiration pressure was increased from 20 to 100 mm water. The calculated membrane area dilation modulus was 7.4 dyn/ cm, which is far below the expected value, and microscopic observations revealed a membrane folding artifact as a possible artifact. These assumptions were strengthened by using a short-duration (3 s) pressure peak of 20-100-20 mm water. The folding then disappeared permanently, but a small (0.31 +/- 0.09%; P < 0.001) area decrease was detected which yields a realistic dilation modulus of 215 dyn/cm. We conclude that membrane folding can critically affect RBC micropipette measurements and that a transient pressure peak can unfold the RBC membrane, thus allowing accurate measurements of RBC geometry.

Cell quality of salvaged blood after total knee arthroplasty. Drain blood compared to venous blood in 32 patients

We used the ConstaVac drainage retransfusion system in 32 patients operated on with cemented tricompartmental knee arthroplasty. The mean total postoperative bleeding was 1.1 L of which 0.7 L was retransfused within 8 hours postoperatively. Samples were taken from the venous blood and drain blood at 2 hours and 6-8 hours postoperatively. The drain blood had low counts for leukocytes and thrombocytes as compared to venous blood, and fibrinogen was almost absent. Incubation at room temperature slightly lowered glucose and pH which made the erythrocytes swell. There was a slight hemolysis in the drain blood at 2 hours. At 6-8 hours the shed blood was closer to normal, especially with regard to hemolysis, but there was a further decrease in glucose. Within this time, there was no change in acidity and no further swelling of the erythrocytes. No clinical adverse reactions were observed and we consider the observed cellular and chemical changes to be of little importance. The quality of filtered drain blood within the analyzed time limit is considered acceptable for clinical use.

Cell volume and shape oscillations in rat type-II somatotrophs at hypotonic conditions

The size and shape of growth hormone (GH)-producing rat type-II somatotrophs was studied during osmotic manipulation. When somatotrophs were exposed to large osmotic stress (200 and 225 mOsm), the peak projected cell area (PCA) was 132.9% +/- 12.6% and 116.8% +/- 2.8% (P < 0.01) and triggered a regulatory volume decrease (RVD) to avoid lysis. At lower osmotic stress (250 mOsm), the rate of swelling was slower, and the volume reached a steady state at 109.4% +/- 2.4% (P < 0.05) and was without RVD. At 275 and 287 mOsm, the swelling was delayed [PCA peak at 3-4 min; 105.8% +/- 1.5% (P < 0.05) and 104.2% +/- 1.7%] and then showed repeated synchronized cycles of swelling and shrink-age (P < 0.05). The data suggest that somatotrophs may have more than one mechanism for volume regulation. One mechanism is for large swelling (classic RVD response), whereas the other represents more physiological mechanisms for regulating the cell volume within a more limited geometry range. For low osmotic stress (250-287 mOsm), the somatotrophs became less spherical during swelling and, thus, were without membrane dilation. Therefore, this type of volume regulation must work independently from membrane stress. Related volume regulation mechanisms may underlie the previously observed volume fluctuations in somatotrophs seen during secretory stimulation with GH-releasing hormone.

Growth hormone deficiency impairs blood clotting and reduces factor VII coagulant activity in rat

To investigate pituitary effects on the vitamin K-dependent coagulation factors, female rats were hypophysectomized (hypox) and treated with growth hormone (GH), cortisone, thyroxine, vitamin K, or saline. After 11 days of treatment, the prothrombin time, platelet count, and factors II, VII, IX, and X were determined. The prothrombin time was 52.9 +/- 1.2% for control rats and 39.1 +/- 0.8% for hypox rats (mean +/- SEM; p < 0.001). All factors decreased after hypophysectomy, reaching significance for factor VII (from 264 +/- 23% to 131 +/- 9%; p < 0.001) and factor IX (from 28.4 +/- 2.2% to 17.1 +/- 2.5%; p < 0.01) while the platelet count was unaffected. When hypox rats were treated with GH, the prothrombin time increased to 50.9 +/- 1.0% (p < 0.001) and factor VII to 299 +/- 10% (p < 0.001). Factor II, IX, and X were slightly increased after GH substitution but not after cortisone, thyroxine, or vitamin K treatment. To summarize, GH is of importance for normal hemostasis in the female rat.

Optical and mathematical corrections of micropipette measurements of red blood cell geometry during anisotonic perifusion

Accurate knowledge of red blood cell (RBC) membrane surface area and cellular volume is critical to understanding the geometric factors that affect RBC deformability. A useful method to determine RBC geometry is via micropipette aspiration in which the cell partially enters the tip of a glass pipette with a diameter of about 2 microns. Measurement of the cell while in the pipette allows calculation of cell geometry, but such measurements are subject to several artifacts. Herein, we analyze the effects of three artifacts on calculated RBC geometry during experimental osmotic manipulation. 1) The pipette internal diameter, as measured optically, requires correction for refractive index and focusing errors; 2) the pipette barrel is tapered rather than cylindrical; 3) the observed RBC outline is affected by a diffraction phenomenon. These optical and mathematical errors were all found to influence the calculated RBC geometry; both absolute values and relative changes during osmotic manipulation were affected. For RBC in isotonic medium, use of the above corrections significantly (p < 0.001) reduced the calculated area by 3.7%, the volume by 7.0%, and the minimum cylindrical diameter by 3.9%. The calculated membrane area dilation for cells exposed to hypotonic media was also significantly reduced; at 200 mOsm, the dilation was 2.8% +/- 0.2% without correction vs. 1.5% +/- 0.2% when all corrections were employed (p < 0.01). We therefore suggest that micropipette aspiration of RBC requires use of these correction techniques to obtain accurate values for RBC geometry and that such correction methods are of particular importance when RBC of different sizes are compared.

Fabrication of glass micropipettes: a semi-automatic approach for trimming the pipette tip

Micropipettes as research instruments are well established in cell biology, including blood rheology. However, the experimental results are, to some extent, dependent on the quality of the pipette itself; it is usually critical to have the desired pipette internal diameter and a perpendicular tip. Pipette fabrication is a two-step procedure involving: a) the pulling of the pipette from a glass capillary; b) the trimming of the pipette tip. A common method to trim and fracture the pipette tip is the use of a melted glass bead on a heated tungsten wire. Previous devices using this method were often associated with problems because the heated wire varied in length with temperature. As a result, the bead together with the attached pipette tip moved markedly and thus hampered the possibility to obtain a perpendicularly cut pipette tip. An improved design, based on the same principle with a melted glass bead, is thus suggested; it eliminates the problem with a moving glass bead and, in addition, allows semi-automatic pipette trimming by utilizing the heat-induced elongation/retraction of the heated wire to fracture the tip without requiring manual assistance. Furthermore, a simple pipette storing technique is suggested, based on standard laboratory utensils, in order to more easily handle fragile pipettes without risk of breakage.

Acute and long-term biphasic volume alterations in rat type-II somatotrophs during GH secretory stimulation

The size and shape of growth hormone (GH)-producing rat (type II)-somatotrophs was studied during secretory stimulation by either human GH-releasing hormone (hGHRH(1-29)) or 50 nM extracellular potassium. A new type of perfusion chamber for light microscopy allowed the interpretation of early changes in cell morphology. The exposure to 10 nM hGHRH caused a significant transient decrease in cell volume to 94.4 +/- 2.1% within 2 s. The cell volume recovered to 99.2 +/- 1.3% at 30 s. A second, more gradual volume decrease then followed (60 s), which stabilized at about 92.5 (8 min) and was still present after 20 min of continuous hGHRH exposure. Potassium, 50 mM, gave an immediate and persistent cell volume increase of about 5%. The fluctuation in rat somatotroph volume after hGHRH exposure correlates to a previously observed biphasic GH-secretory pattern involving an initial burst secretion and a second slow phase secretion. The transient early volume decrease may reflect ion fluxes across the membrane and/or the response of the cytoskeleton to calcium mobilization during the GH-secretory onset. The second, persistent, volume decrease closely correlates to the calculated volume of lost GH vesicles.

Early morphological detection of estramustine cytotoxicity measured as alteration in cell size and shape by a new technique of microperifusion

The present study describes a new microscopic perifusion technique for detecting momentary alterations in cell volume and shape. The method has been applied for evaluating early signs of cytotoxicity following chemotherapeutic treatments. The effects of estramustine phosphate (EMP) have been evaluated. EMP is a complex between oestradiol-17 beta and the alkylating agent nor-nitrogen mustard and has recently demonstrated a marked cytotoxicity against malignant glioma cells. The results showed a concentration-dependent increase in cell size and a concomitant decrease in shape factor following EMP-treatment of glioma cells. These changes correlated with cytotoxicity evaluated as cell proliferation and cell membrane alterations shown by 86Rb fluxes and ultrastructural visible membrane damage. The colon cancer line HT-29 displayed no reactions at all following EMP treatment. It is suggested that acute alterations in cell morphology and shape display a strong correlation to the cytotoxicity of EMP encountered by traditional cell culture systems. The findings are discussed with respect to cell membrane disturbances caused by EMP and its potential role as an early test of cytotoxicity.

Volume regulation in mouse pancreatic beta-cells is mediated by a furosemide-sensitive mechanism

A possible role for loop diuretic-sensitive Cl-/cation cotransport in volume regulation in the pancreatic beta-cells was investigated by measuring 86Rb+ efflux from beta-cell-rich pancreatic islets as well as the size of isolated beta-cells under different osmotic conditions. Lowering the osmolarity to 262 mosM (83% of control) resulted in a rapid cell swelling which was followed by regulatory volume decrease (RVD). RVD was completely inhibited by furosemide (1 mM), an inhibitor of Cl-/cation co-transport. The hypotonic medium (262 mosM) induced a rapid and strong increase in 86Rb+ efflux from beta-cell-rich mouse pancreatic islets and the furosemide-sensitive portion of the efflux was significantly increased. A slightly less hypotonic medium (285 mosM, 90% of control) induced only cell swelling and no RVD. With this medium only a marginal increase in 86Rb+ efflux was observed. Increasing the osmolarity by adding 50 mM NaCl (final osmolarity: 417 mosM, 132% of control) induced a rapid cell shrinkage but no regulatory volume increase (RVI). When the osmolarity was increased from a slightly hypotonic medium (262 mosM) to an isotonic medium (317 mosM) an initial cell shrinkage was followed by RVI. This RVI was inhibited by 1 mM furosemide. The data suggest that RVD as well as RVI in the beta-cells are mediated by loop diuretic-sensitive cotransport of chloride and cations and that these cells show a threshold for hypotonic stimulation of RVD.

Effect of hypophysectomy and growth hormone substitution on red blood cell morphology and filterability in rats

Growth factors, including insulin, are known to stimulate erythroid cell formation in vitro. This somatotrophic effect of insulin might be involved in blood abnormalities in diabetes mellitus. We therefore investigated whether growth hormone (GH) affects the morphology or filterability of circulating red blood cells (RBCs) in hypophysectomized rats. After hypophysectomy, rats became anemic with a decrease in hematocrit, hemoglobin concentration, RBC count, and reticulocytes. The RBC membrane area was enlarged, giving an increased area-to-volume ratio compared with the control RBCs. The calculated minimum cylindrical diameter (MCD) and resistance to initial folding of the RBC decreased after hypophysectomy, and was confirmed by an enhanced filtration of RBCs through 3 microns Nucleopore membranes. The number of filter clogging particles was also lower in hypophysectomized rats than in control rats. Substitution for 21 days with bovine GH (via subcutaneously implanted osmotic minipumps) normalized RBC morphology and filterability. After withdrawal of GH, all parameters returned toward the presubstitutional levels. Neither cortisone nor thyroxine had any measurable effect on RBC morphology or deformability, indicating that GH deficiency contributes to the abnormal RBC morphology and rheology seen after hypophysectomy.

Insulin-driven erythropoiesis may underlie impairment of erythrocyte deformability in hyperinsulinaemic, hyperglycaemic ob/ob-mice

The circulating erythrocytes in hyperglycaemic and hyperinsulinaemic obese (ob/ob) mice are enlarged with a decreased erythrocyte filtrability and an abnormally low resistance to osmotic stress. These changes probably reflect aberrations of erythropoiesis, as evidenced by endhanced staining for iron in the bone marrow, reticulocytosis, and increased erythrocyte volume fraction. Mature erythrocytes, reticulocytes, and late-phase basophilic erythroblasts were found to have larger diameters than their counterparts in control mice while myelopoiesis appeared to be unaffected. The average erythrocyte also displayed an increased cell volume and a decreased haemoglobin concentration. It is suggested that the stimulation of the erythroid cell line in ob/ob-mice might be a consequence of the hereditary hyperinsulinaemia.

Morphology and filterability of red blood cells in neonatal and adult rats

Red blood cell (RBC) deformability in rats of various ages was assessed by filtration (3 micron Nucleopore membranes). Neonatal rat RBC (1 d old) had lower filterability, both in terms of RBC incremental volume (9.97 +/- 1.85 versus 0.33 +/- 0.28 nL at 180 d of age, mean +/- SD, p less than 0.001) and the number of filter clogging particles (25.7 +/- 3.1 versus 18.9 +/- 3.4 RBC x 10(3)/s, p less than 0.001). The lower filterability correlated with a larger RBC volume (169 +/- 12.6 versus 69 +/- 3.2 microns 3, p less than 0.001) and with a wider minimum cylindrical diameter (3.87 +/- 0.15 versus 2.84 +/- 0.05 microns, p less than 0.001). Almost all of the neonatal RBC had a minimum cylindrical diameter exceeding the 3 microns nominal pore size of the filters. The calculated resistance to initial folding was also significantly greater, as indicated by a static bending analysis of initial deformation. However, when the larger size of neonatal RBC was taken into consideration, and thus their greater projected area on which forces are applied, they appear to be at least as deformable as the adult type RBC. This finding may explain the contradiction between RBC filtration experiments and other approaches based on RBC deformations in shear flow, which have been unable to detect a hampered flexibility of neonatal RBC. In view of the more pronounced differences between neonatal and adult RBC in rats than in human subjects, the rat is an interesting model for studying this physiologic phenomenon in newborns.

Volume regulation in mouse pancreatic islet cells as studied by a new technique of microperifusion

A new technique was designed to analyse whether pancreatic islet cells are able to regulate their volume in anisotonic media. The projected cell area of individual cells was continuously observed, and the corresponding volume calculated during microperifusion with media of different osmolarities. In isotonic medium (317 mosmol) the cell volume was stable during perifusion and decreased by 17 or 25% when the osmolarity was increased (sucrose) to 417 or 517 mosmol. Reducing the medium osmolarity to 285 mosmol resulted in a volume reduction of about 7%. No evidence for cell volume regulation was observed in these media. However, reducing the medium osmolarity to 262 mosmol induced an immediate and rapid cell swelling of approximately 14%, after which the initial cell volume was regained within 9 min. The data suggest that the pancreatic islet cells are equipped with mechanisms for regulatory volume decrease that appear to be activated when the cell volume is increased above a certain limit.

A new red blood cell filtration device with improved time resolution and its application to the impaired RBC deformability in the diabetic ob/ob mouse

A new filtration device and blood handling technique for the assessment of RBC deformability in small blood samples is described and used to study RBC deformability in adult obese-hyperglycemic ob/ob-mice and normoglycemic controls. The new filtration device was designed to improve the time resolution during RBC incubation. Test and control RBC suspensions were directly filtered from two identical incubation chambers under a constant pressure of 1200 Pa. Nuclepore filters (3 microns) were mounted on top of several standard test tubes into which the filtrate was subsequently collected and weighed. Because the RBCs were resuspended to a very low (0.01%) hematocrit, the average number of RBCs passing each pore was less than 10. Therefore, any detectable difference must reflect the physical properties of RBCs, e.g. shape or viscoelasticity, whereas the role of white blood cells is negligible. When ob/ob-mouse RBCs were studied with the new technique they showed impaired filtrability as compared with control RBCs, both when incubated without glucose and with glucose present at the same concentration as that recorded in the RBC donating mouse.

Increased size and biconcavity in red blood cells of obese-hyperglycaemic mice

Blood from non-inbred obese-hyperglycaemic ob/ob-mice or normoglycaemic controls was fixed in glutaraldehyde and embedded in plastic on glass slides. In vertically oriented red blood cells (RBCs) the diameter, central thickness, and toroidal thickness were measured at the diametrical cross section. For each RBC, the area, volume, and cross-sectional profile were calculated and used to analyze the mechanical properties of the corpuscle. In both types of mice, the diameter correlated positively with the central thickness and negatively with the toroidal thickness, suggesting a variation not only in size but also in biconcavity; the smaller the diameter, the more biconcave the disc. However, ob/ob-mouse RBCs were both larger and more biconcave than those in control mice. These differences in size and shape are suggested to explain why ob/ob-mouse RBCs exhibit a decreased deformability in filtration experiments.

Altered shape and size of red blood cells in obese hyperglycaemic mice

Red blood cells (RBCs) from hyperglycaemic ob/ob-mice, normoglycaemic controls, and a healthy man were sucked into a narrow capillary, photographed and measured. Mouse RBCs had a smaller diameter than human ones. Although of normal diameter, the ob/ob-mouse RBCs exhibited increased area and volume, and more frequently than control RBCs had a minimum cylindrical diameter greater that 3 micron. Cross-sectional profiles with minimum bending resistance were computed for RBCs of mean area and volume. The diameters of these theoretical profiles agreed closely with those empirically observed, in both mice and man. The profile of ob/ob-mouse RBCs predicted a greater resistance to corpuscle bending than the control profile. It is concluded that changes in shape and size explain the decreased filtrability of diabetic ob/ob-mouse RBCs. The results also suggest that the actually occuring smooth biconcavity is in general the RBC shape with maximum flexibility.

Decreased deformability of erythrocytes in hyperglycaemic non-inbred ob/ob mice

The deformability of erythrocytes from non-inbred ob/ob mice and lean controls was analyzed by filtration through Nuclepore polycarbonate under constant pressure. At the age of 1-2 months there was no difference in erythrocyte filtrability between the two types of mice, whereas from 3 months the ob/ob mouse erythrocytes exhibited a markedly decreased deformability. The filtrability of erythrocytes was sensitive to osmotic pressure (NaCl or glucose). However, the difference between normal and ob/ob mouse erythrocytes was not due to acute osmotic effects of the hyperglycaemia in the ob/ob mice. When filtration was performed in the same glucose concentration as that recorded in the blood of the erythrocyte-donor animal, the difference in filtrability between adult normal and ob/ob mice remained large and significant (p less than 0.01). Moreover, the most pronounced hyperglycaemia occurred in young ob/ob mice with normal erythrocyte filtrability. It is suggested that non-inbred ob/ob mice are a useful model for studying the damaging influence of diabetes on erythrocyte deformability.