Determination of Skin Blood Flow by 133Xe Washout and by Heat Flux from a Heated tc-Po2 Electrode

¹³³Xe washout measurements were used to determine cutaneous and subcutaneous blood flow beneath a specially designed double-thermostated tc-Po₂ electrode. The skin blood flow was determined using thermal methods based on reduced heat dissipation during blood flow cessation. A total of 20 measurements were performed on two healthy volunteers, using the volar side of the right forearm as the experimental area. Cutaneous as well as subcutaneous blood flow increased with increasing electrode temperature. The cutaneous blood flow increased from 12.3 ± 1.3 ml (100 g)^-1-min^-1 (37C) to 49.1 ± 5.4 ml (100 g)^-1.min^-1 (45C) and the subcutaneous values from 20.9 ± 0.2 ml (100 g)^-1 -min^-1 to 57.3 ± 0.5 ml (100 g)^-1 -min^-1. Preheating of the measuring area or injection of papaverine as blood flow accelerator did not increase the maximum blood flow values. A considerable inter-individual difference between cutaneous and subcutaneous blood flow was observed, but in spite of that a good overall correlation between the ¹³³Xe washout measurements and the two thermal flow measurements was found (r = 0.932 and 0.945, respectively). It is concluded that in some cases, but not always, measurements of tc-Po₂ at electrode temperatures of 45C take place on a maximally perfused skin and that it is possible to determine skin blood flow by means of determinations of the heat dissipated from the tc-Po2 electrode to the underlying skin.     

Hyperkalaemia associated with haemorrhagic shock in rabbits: mochfication by succinylcholine, vecuroniurn and blood transfusion

In haemorrhagic patients, hyperkalaemia may occur after succinylcholine administration. We investigated in haemorrhagic rabbits whether vecuronium caused hyperkaelemia and if blood transfusion prevented succinylcholine-induced hyperkalaemia.
Rabbits were lightly anaesthetized with halothane/N₂O and 30-35 ml/kg blood were withdrawn to cause arterial pH to decrease to ∼ 7.0-7.1. Group C (n = 12) received 3 ml saline, Group S (n = 13) received succinylcholine lmg/kg. Group V (n = 7) received vecuronium 0.25 mg/kg and Group T (n = 9) was transfused with 10 ml/kg blood 10 min prior to receiving succinylcholine 1 mg/kg. K⁺ analysis was repeated at 5 min, and at 10 min in most animals.
Haemorrhage increased K⁺ (mmol·1^-1, mean ± SD): Group C, 3.4±0.3 to 6.8±1.8; Group S, 3.8±0.5 to 6.9±2.3; Group V, 3.8±0.3 to 7.1±1.9; Group T, 3.6±0.5 to 7.6±2.9. K⁺ decreased in Group T (to 5.4±1.8) after blood transfusion. K⁺ increased at 5 min in Group S (to 8.7±2.6) and at 10 min for Group C (to 8.4±1.7) and Group T (to 7.2±2.3). The K⁺ increase at 5 min for Group S (1.8±0.8) was significantly higher than those for Group C (1.0±0.6) or Group V (0.9±0.4), but was not different from that of Group T (1.5±0.7).
We conclude that haemorrhage and succinylcholine cause hyperkalaemia in rabbits. Muscle relaxation itself does not appear to be a factor, but transfusion may lessen the hyperkalaemia.     

Quantifying the interaction of vecuronium with enflurane using closed-loop feedback control of vecuronium infusion

The influence of different levels of enflurane anaesthesia on infusion requirements of vecuronium was studied in 40 adult surgical patients. Ninety percent neuromuscular block was maintained by computer controlled infusion of vecuronium. During the first 90 min study period all patients received fentanyl-nitrous oxide-oxygen (2:1) anaesthesia. For the following 90 min the patients were randomly assigned to receive enflurane at different end-tidal concentrations: group I, control, fentanyl-nitrous oxide anaesthesia; group II, enflurane 0.3%-nitrous oxide; group III, enflurane 0.6%-nitrous oxide; group IV, enflurane 0.9%-nitrous oxide. Every patient served as his/her own control and the changes of vecuronium infusion requirements were determined individually. When the administration of enflurane was started, vecuronium infusion requirements decreased progressively until 90 min. In group II the infusion rate lowered from 80±28 to 56±20 μg . kg^-1 . h ^-1, in group III from 61 ±29 to 34±17 μg . kg^-1 . h^-1 and in group IV from 65±20 to 30± 14 μg . kg^-1 . h^-1. In the control group the infusion rate decreased during the three hour study period from 69± 17 (first 90 min period) to 59± 16 μg . kg^-1 . h^-1 (second 90 min period). Enflurane reduces the dose requirements of vecuronium administered by continuous infusion in a dose- and time-dependent manner.     

Modulation of ryanodine-induced contractures in human skeletal muscle pretreated with dantrolene

Dantrolene seems to be the causal therapy in malignant hyperthermia (MH) crisis but the complex mechanisms of MH and dantrolene therapy are still not fully understood. The influence of dantrolene on ryanodine-induced contractures has been reported in animal studies only. In the present study 20 patients from] 7 families were tested for MH using the protocol of the European Malignant Hyperthermia Group. In addition ryanodine-induced contractures were evaluated following bolus application of 10.0 μmol · 1^-1 ryanodine. After pretreatment with 1 μimol · 1^-1 dantrolene ryanodine-provoked contractures developed significantly later in MHS (15.8±1.8 min) and MHN (46.0±4.2 min) muscle specimens than after ryanodine alone (MHS 4.8±0.7 min), (MHN 13.7±0.9 min). They were no longer observed in either group after pretreatment with 5 μimol · 1^-1 dantrolene. We conclude that dantrolene is able to attenuate ryanodine-induced contractures dose-dependendy, and therefore it is speculated that dantrolene could specifically act at the ryanodine receptor binding site.     

Efficiency of an External Support to Reduce Lipid Infiltration into Venous Grafts: In Vitro Evaluation

Abstract: Excessive distension of venous grafts due to arterial pressure enhances the convective water transport (filtration flow) through the vessel wall, and thus might affect the infiltration of macromolecules such as lipoproteins. In this paired experimental study, filtration velocities were measured at 100 mm Hg for canine jugular veins with or without external supports of expanded poly-tetrafluoroethylene (ePTFE) arterial prostheses. In addition, to assess the effect of filtration velocity on lipid infiltration or uptake, canine jugular veins were wrapped over half of their lengths with ePTFE arterial prostheses and perfused with dog serum containing ³H-cholesterol at a pressure of 100 mm Hg. At 100 mm Hg, the average filtration velocity of the wrapped jugular veins was 7.9 ± 1.3 ± 10^-6 cm/s whereas the average filtration velocity of the unwrapped veins was 27.3 ± 2.7 ± 10^-6 cm/s (p < 0.005). Moreover, the unwrapped veins had a significantly higher uptake rate of labeled cholesterol than the wrapped veins (10.9 ± 7.3 ± 10^-4 cm/h and 5.0 ± 1.6 ± 10^-4 cm/h, respectively, p < 0.005). In conclusion, under arterial pressure, veins experience excessive distention, which leads to significant increases in both filtration flow and cholesterol uptake. An external wrap or support of ePTFE material protects veins from excessive distension and thus may prevent atherosclerosis in venous grafts by reducing cholesterol uptake.     

Renal effects of temocapril hydrochloride (CS-622) in patients with benign nephrosclerosis

SUMMARY: The short-term effects of temocapril, a new angiotensin-converting enzyme inhibitor (ACE-I), on renal function were investigated in 10 patients with benign nephrosclerosis (56.2 ± 7.2 years, mean ± SD). Renal plasma flow and glomerular filtration rate (GFR) were examined before and after 12-week administration, using ¹³¹I-hippuran and ^99mTc-DTPA, respectively. Temocapril (mean 4.5 mg/day) decreased systolic and diastolic blood pressure (from 162 ± 6 to 140 ± 12 mmHg, P <0.001, and from 101 ± 5 to 89 ± 8 mmHg, P <0.001, respectively). Temocapril increased both renal plasma flow (from 323 ± 67 to 367 ± 72 mL/min/1.73 m² P <0.05) and GFR (from 74 ± 14 to 81 ± 15 mL/min/1.73 m², P <0.05). These data show that short-term administration of temocapril improves renal function in patients with benign nephrosclerosis.     

Disopyramide Anticholinergic Action

The effect of disopyramide on cholinergic transmission has been studied using the frog isolated abdominis rectus preparation and the guinea pig isolated vas deferens hypogastric nerve preparation. Disopyramide (2 × 10^-5 mol litre^-1) reduced the response of the abdominis rectus to carbachol (1.36 × 10^-6 — 4.8 × 10^-5 mol litre^-1). Furthermore, disopyramide (1 × 10^-6 —3 × 10^-4 mol litre^-1) produced a concentration-dependent reduction in the response to carbachol (5.46 × 10^-6 mol litre). The response to potassium chloride (3.34 × 10 mol litre^-1) was unaltered by disopyramide (1 × 10 —3 × 10^-4mol litre^-1). Disopyramide produced a dose-related ganglionic blockade at concentrations greater than 2 × 10^-5 mol litre^-1. Complete blockade to ganglionic transmission occurred at 3 × 10^-4 mol litre^-1 disopyramide.     

Seminal fibronectin-like antigen and transferrin concentrations in infertile and fertile men

Summary.  Fibronectin like antigen (Fn) and transferrin (Trs) levels were measured in the seminal plasma of 40 fertile and 102 infertile men. The concentrations of both proteins were significantly ( P <0.001) higher in the fertile controls compared to the infertile groups. The levels of Fn and Trs (mean value ± SEM) in the fertile men were 857.9 ± 9.8 μg ml^-1 and 164.0 ± 6.5 μg ml^-1, respectively; in the azoospermic men ( n = 17) 552.7 ± 24.65 μg ml^-1 and 20.7 ± 2.19 μg ml^-1, respectively; in the group of severe oligozoospermia ( n = 35) 568.34 ± 25.7 μg ml^-1 and 31.1 ± 4.18 μg ml^-1, respectively; in the moderate oligozoospermic group ( n = 8) 572.50 ± 47.9 μg ml^-1 and 43.4 ± 15.4 μg ml^-1 respectively, and in the asthenozoospermic group ( n = 26) 512.76 ± 40.4 μg ml^-1 and 47.0 ± 7.9 μg ml^-1, respectively. Of special interest was the finding from a group of 16 normospermic men (partners of couples with unexplained infertility) who showed significantly lower levels of Fn like antigen, 632.5 ± 26.9 μg ml^-1 ( P <0.001) and Trs 41.8 ± 6.94 μg ml^-1 ( P <0.0001) compared to normals. No correlation was found between Fn levels with either Trs or FSH levels or sperm count. In conclusion, our results indicate that male infertility is associated with changes in seminal plasma Fn like antigen concentrations and that it can be possibly used as an index of sperm fertilizing capacity.     

Erythrocyte counts in the cerebrospinal fluid associated with continuous spinal anaesthesia

Continuous spinal anaesthesia technique can be associated with peridural haemorrhage due to blood vessel damage caused by the needle or the catheter. We studied whether thrombosis prophylaxis or anticoaguladon medications increase the risk of subarachnoid haemorrhage when continuous spinal anaesthesia is used. Twenty arthroplasty patients received low-molecular-weight heparin preoperatively and twenty-two vascular surgery patients received heparin (100 IU kg^-1) peroperatively; eight of the latter patients were on regular preoperative antiplatelet medication. Twenty-four prostate surgery patients, not exposed to heparin or other drugs affecting coagulation, served as controls. A 22-gauge spinal catheter was used and bupivacaine was injected through the catheter. Within the following 24 hours, 4—5 cerebrospinal fluid samples were collected for erythrocyte counts. In the arthroplasty and the vascular group there were five patients each and in the control group seven patients with more than 100 × 10⁶ 1^-1 erythrocytes in at least one of the samples. The highest erythrocyte count was 23900 × 10⁶ 1^-1 in a control patient, The 24-hour sample was blood-tinged (erythrocytes >1000X10⁶ 1^-1) in two patients in the arthroplasty group, in one patient in the vascular group and in four patients in the control group. In spite of the haemorrhages detected in this study, no related neurological symptoms or other serious consequences were observed. The risk of subarachnoid haemorrhage was not increased by drugs affecting coagulation.     

Effect of FTY720 on immunoregulation in concordant xenotransplantation

Abstract The present study was designed to analyze the immunosuppressive activity of FTY720 in concordant xenotransplantation. When T and B lymphocytes of human peripheral blood were incubated with FTY720, the number of viable cells decreased in a dose-dependent manner at doses higher than 4×10^-5 M. DNA fragmentation was observed at doses higher than 4×10 ^-5 M in B cell-rich fractions. These data demonstrate that FTY720 is cytotoxic to B lymphocytes as well as T lymphocytes and apoptosis may play an important role in this cytotoxicity. Golden Syrian hamsters were the donors and Lewis rats the recipients of skin grafts. The recipients were divided into the following four groups; (1) untreated recipients, (2) FTY720 (5mg/kg per day) was administered orally for 8 days (days -1–6), (3) FK 506 (1 mg/kg per day) was injected i. m. for 7 days (days 0–6), and (4) FK506 (1 mg/kg per day) was injected i.m. for 7 days (days 0–6) and FTY720 (5 mg/kg per day) was administered orally for 8 days (days-1–6). The mean graft survival times in groups 1–4 were.7 ± 0.52 days ( n = 6), 12.0 ± 0.71 days ( n = 6), 13.2 ± 1.6 days ( n = 6), and 37.7 ± 4.3 days ( n = 6), respectively. There was a significant difference in the mean survival time between groups one and four. Combined therapy with FTY720 and FK506 is a useful tool for immunoregulation in xenotransplantation.     

The Effects of Halothane and Methoxyflurane Metabolites on Lipolysis In Vitro

Die Wirkungen von Halothan und Methoxyfluran auf den Lipidstoffwechsel bei Ratten wurden durch das Studium der Wirkung ihrer Metaboliten auf die Lipolyse in vitro weiteranalysiert. Trifluoroessigsaures Natrium und Trifluoroazetaldehyd verursachten keine Änderungen der Lipolyse in vitro. Trifluoroäthanol und Natriumfluorid stimulierten die Lipolyse in vitro, erkennbar aus der erhöhten Anhäufung von freien Fettsäuren in den Fettgeweben und erhöhter Freisetzung von Glyzerol in das Inkubationsmedium.
Bei Trifluoroäthanol waren die E_max-Werte 3,85 μEq/g/Stunde für die freien Fettsäuren und 1,10 μmol/g/Stunde für Glyzerol. Die K_A-Werte waren 5,3 × 10^-5 M bzw. 6,6 × 10^-5 M. Bei Natriumfluorid waren die E_max-Werte 2,23 μEq/g/Stunde für die freien Fettsäuren und 0,38 μmol/g/Stunde für Glyzerol. Die K_A-Werte waren 1,4 × 10^-4 M bzw. 1,2 × 10^-4 M. Propanolol (5 × 10^-6 M) blockierte die lipolytische Wirkung von Trifluoroäthanol, hatte aber keinen Effekt auf die durch Natriumfluorid induzierte Lipolyse. Auf Grund dieser Ergebnisse wird angenommen, daß die erwähnten Metaboliten für die Störungen des Lipidstoflwechsels und die Fettveränderungen in der Leber verantwortlich sein konnten, die nach Halothan- und Methoxyflurannarkosen beobachtet wurden.     

The duration of action of mivacurium is prolonged if preceded by atracurium or vecuronium

We studied 45 patients (ASA I-II) during propofol-alfentanil-N₂O-O₂ anaesthesia to determine if recovery from neuromuscular block induced by mivacurium is influenced differently by prior injection of atracurium or vecuronium. Neuromuscular function was monitored by adductor pollicis EMG. Patients were randomized to receive two dosesof either mivacurium (150 and 70 μg kg^-1), atracurium (350 and 75 μg kg^-1) or vecuronium (70 and 15 μg kg^-1) followed by a final dose of mivacurium 70 μg kg^-1. The second and third doses of the muscle relaxants were administered at 25–30% recovery of the E₁ (first EMG response in the train-of-four series). Following the final dose of mivacurium, the EMG response recovered to 25 and 95% in 10.4±3.9 and 19.7±5.7 min (mean±SD), respectively, if mivacurium was the only muscle relaxant. Respective times were 100% longer if mivacurium had been preceded by atracurium (23.8 ± 3.3 and 39.8±6.9 mm) or vecuronium (22.6±3.5 and 44.1 ±7.9 min) ( P =0.000l). The 25–75% recovery times in the three groups were 4.9±1.0, 8.7±2.4 and 10.5±2.5 min, respectively ( P =0.0001). Our results indicate that there is no benefit in giving mivacurium at the end of surgery after peroperative use of atracurium or vecuronium.     

Disturbance of hepatocellular integrity associated with propofol anaesthesia in surgical patients

Propofol anaesthesia has not been associated with any hepatic consequences. We used glutathione transferase Alpha (GSTA), a very sensitive indicator of hepatocellular integrity, to evaluate the effect of propofol on the liver. Total intravenous anaesthesia was induced and maintained with propofol without any supplements in 30 female patients undergoing breast surgery. Ten healthy female volunteers given the lipid vehicle of propofol served as controls. Serum GSTA concentration was measured with a sensitive time-resolved immunorluorometric assay. Total intravenous propofol anaesthesia was stable and postoperative nausea negligible. A significant increase in GSTA from 3.1 μg · 1 ^-1 (mean baseline) to 10.0 μg · 1 ^-1 (mean peak) was noted after propofol infusion, indicating subclinical disturbance in hepatocellular integrity. No change in aminotransferases and no clinical signs of hepato-toxicity were observed. A small increase in GSTA from 2.4 μg · 1^-1 (mean baseline) to 4.1 μg· 1^-1 (mean peak) was observed during lipid infusion.
We detected a subclinical disturbance in hepatocellular integrity after propofol anaesthesia for breast surgery. The mechanisms of hepatocellular impairment are not clear but the lipid vehicle of propofol alone does not explain it.     

Halothane-Induced Lipolysis in Vitro in the Rat

Unsere früheren in vivo-Befunde über Halothan-induzierte Lipolyse in der Ratte wurden nun weiter in vitro analusiert, wobei epididymale Ratten-Fettläppchen inkubiert wurden. Auch in vitro stimulierte Halothan eine Lipolyse, erkennbar an einer vermehrten Anreicherung freier Fettsäuren im Fettgewebe und einer erhöhten Freisetzung von Glycerol in das Inkubations-medium. E_max-Wert der freien Fettsäuren war 5,3 μ Eq/g pro Stunde, der für Glycerol 0,83 μMol/g pro Stunde. Die K_A-Werte waren 9,1 ± lO^-5M, bzw. 1,1 ± 10^-4M bei Halothan. Propranolol blockierte in einer Konzentration von 5 ± 10^-6M die lipolytische Wirkung von Halothan komplett. Aufgrund dieser Ergebnisse darf angenommen werden, dass die Halothan-induzierte Lipolyse auf einer direkten Stimulation der sympathischen Beta-Rezeptoren in den Fettzellen beruht.     

Uniqueness of Sperm mtDNA as Compared to Somatic mtDNA in Ram

Sperm mtDNA exhibits unique physicochemical properties compared with mtDNA from somatic tissues in the ram. The buoyant density of sperm mtDNA was 1.6983 g/cm³ while the brain, heart and liver mtDNAs was about 1.7005 g/cm³. The Tm of the liver and sperm mtDNA was 71.0°C and 69.5°C, respectively. The G + C content of sperm mtDNA was 3.0 moles % lower than the liver mtDNA. The contour length of the circular sperm mtDNA was 5.01 μm compared with the liver mtDNA with contour length of 5.33 μm.     

Isolation and characterization of plasma membranes containing LH sensitive adenylate cyclase from a Leydig cell tumour

An LH sensitive adenylate cyclase from a tumour Leydig cell has been investigated. The plasma membranes, prepared by a 2 phase (dextran-polyethylene glycol) centrifugation method were found to have the following properties: In the presence of LH plus p(NH)ppG (guanosine 5'-β,λ-imido triphosphate) or fluoride ions, maximum adenylate cyclase activity was obtained in the plasma membranes with 4 to 6 mM Mg²⁺ plus 0.33 to 2 mM ATP. LH alone stimulated adenylate cyclase activity 2-fold when compared with basal activity and the time course of cyclic AMP production was linear up to 45 min. With GTP (10^-5M) and GTP plus LH, adenylate cyclase activity was increased 3 and 6-fold, respectively, for up to 20 min and thereafter declined. In contrast p(NH)ppG (10^-5 M) and p(NH)ppG plus LH increased adenylate cyclase activity 7 and 14-fold which was maintained for at least 45 min. Fluoride ions increased the enzyme activity linearly over 45 min approx 18-fold. When GTP or p(NH)ppG were added alone there was a lag time of activation of approximately 10 min which was abolished by the addition of LH. GTP but not p(NH)ppG at concentrations greater than 10^-4 inhibited basal and LH stimulated adenylate cyclase when compared with 10^-5 M GTP. The tumour Leydig cell adenylate cyclase is thus essentially similar to other hormone sensitive somatic cells. The present study makes it feasible to prepare plasma membranes by a simple method from large quantities of pure Leydig cells.     

A New Device for Endothelial Cell Seeding of a Small-Caliber Vascular Prosthesis

Abstract: A device permitting homogeneous endothelial cell seeding of a small-calíber arteríal prosthesís has been developed. The prosthesis is maintained firmly attached to a rotative scaffolding device. This device is activated by an electrical motor at constant and adjustable speed. The whole system is maintained at 37°C in a cell culture incubator. The 4 mm internal diameter polytetrafluoroethylene (PTFE) prosthesis was coated with biological glue and seeded with human saphenous vein endothelial cells obtained by mechanical detachment. Cell seeding density was 2.10⁴ cells/cm² (Group A, n = 6) or 10⁵ cells/cm² (Group B, n = 6). Rotation speed was 8 revolutions per hour (rph) during 90 min. Analysis of the homogeneity of cell seeding was permitted by cell counts on five different segments of the prosthesis. Each longitudinal segment was analyzed at three different subsegments of the circumference. The average adhesion was 43 ± 4% in Group A and 38%± in Group B of seeded cells. No difference could be observed between the different segments and subsegments. In the two groups, cells were spread, and in Group B, a complete endothelial cell layer was obtained on the graft surface. This study permits validation of the device to allow homogeneous cell seeding in an arterial prosthesis.     

Potency and maintenance requirement of atracurium and vecuronium given alone or together

A synergism exists between some competitive muscle relaxants. However, maintenance requirement of a combination of muscle relaxants has been evaluated only in paediatric patients. We studied 45 elective adult surgical patients (ASA I-II) during propofol-alfentanyl-N₂O-O₂-anaesthesia. The first 30 patients were randomized to receive either atracurium or vecuronium to create individual dose-response curves for these muscle relaxants. ED₉₅-values for atracurium and vecuronium were 260±9 and 59±3 μg · kg^-1, respectively (mean±s.e.mean). Requirements of atracurium and vecuronium to maintain an 85–95% neuromuscular blockade were 301 and 83 μg kg^-1 h^-1, respectively. An additional 15 patients received a combination of atracurium and vecuronium (cAV) in an equipotent dose ratio. An ED₉₅ of a cAV was 94± 7 μg · kg^-1 of atracurium together with 21±2 μg · kg^-1 of vecuronium, or 72±6% of one ED₉₅ dose of a parent agent. Potentiation was significant ( P =0.0001). A maintenance requirement of a cAV was 120 μg kg^-1 h^-1 of atracurium together with 27 μg kg^-1 h^-1 of vecuronium. Thus, a significant potentiation was maintained also during the course of anaesthesia. A cAV had an effect like one intermediate-acting agent. If a cAV is used instead of using atracurium or vecuronium alone, the maximal reduction of drug consumption would be approximately 30%.     

Effect of succinylcholine on subsequently administered mivacurium in children

The interaction between mivacurium and succinylcholine when mivacurium was administered during the early recovery from succinylcholine block was studied in 30 children 2-12 years of age anaesthetized with propofolalfentanil-N₂O-O₂. Neuromuscular response was monitored by adductor pollicis EMG. Fifteen patients received 200 μg. kg^-1 of mivacurium (Group M), and another fifteen received 1500 μg. kg^-1 of succinylcholine followed by 200 μg. kg^-1 of mivacurium when the first EMG response recovered to 5% of calibration value (Group SchM). Plasma cholinesterase (pChE) activity was normal in each patient. The recovery times following mivacurium did not differ between the two groups. Times required for recovery of the first EMG response from 25 to 75% of full EMG recovery were 3.6±1.0 (mean±SD) and 4.0±0.7 min for the Groups M and SchM, respectively. The time from administration of mivacurium to the recovery of train-of-four ratio 0.70 was 13.2±3.3 min for the Group M and 13.6±3.1 min for the Group SchM (NS). Thus, in patients with normal pChE activity preceding administration of succinylcholine did not influence the recovery of neuromuscular function from subsequent mivacurium.     

Intestinal Vascular Responses to Dopamine During Fentanyl-Nitrous Oxide Anaesthesia, Supplemented with Dixyrazin

Intestinal haemodynamics in response to continuous i.v. administration of dopamine were investigated in cats anaesthetized with fentanyl-nitrous oxide either with or without supplement of dixyrazin. A dose-dependent vasodilatation was observed in the dopamine dose range 2.5–35 μg-kg^-1 min ^-1 and the subsequent maximal intestinal blood flow increase was 121%. No net intestinal vasoconstriction was evident even at the largest dopamine doses, although the vascular response reached a plateau at 17.5 μg-kg^-1 min^-1. Control experiments during chloralose anaesthesia gave similar results. Changes in mean arterial pressure and heart rate were small. Renal blood flow was virtually unchanged at dopamine doses below 10 μg-kg^-1 min^-1, while renal vasoconstriction was evident following dopamine doses above that level. The addition of i.v. dixyrazin (0.15-0.30 mg kg^-1) to the fentanyl-nitrous oxide anaesthesia substantially potentiated the intestinal vasodilator response to i.v. dopamine and the maximal blood flow increase was 183% at 10–15 μg kg^-1 min^-1. In vitro experiments using mesenteric resistance vessels from the rat demonstrated a dose-dependent relaxation to dopamine. At very large doses this response was counteracted, but not reversed into vasoconstriction by dopamine-induced a-adrenergic stimulation.