Hepatic energy charge and adenine nucleotide status in rats anesthetized with halothane, isoflurane or enflurane

BACKGROUND

Volatile anesthetics are known to have varying effects on hepatic oxygen supply in vivo and have been shown to depress hepatic mitochondrial respiration and so energy charge in vitro. However, the effect of halothane, isoflurane and enflurane on hepatic adenine nucleotide status in vivo has not been evaluated.

METHODS

Ninety male rats were exposed to 40% oxygen (n = 22) or 40% oxygen in equipotent (1 MAC) concentrations of halothane (1%) (n = 23), isoflurane (1.4%) (n = 22) or enflurane (2%) (n = 23) for 2 hours. All animals were then administered intraperitoneal pentobarbital and anesthesia continued and laparotomy was performed. A liver biopsy was taken for determination of hepatocellular adenosine-5-triphosphate (ATP), adenosine-5-diphosphate (ADP) and adenosine-5-monophosphate (AMP) and computation of energy charge (EC) from ¿(ATP + 1/2ADP)+(ATP + ADP + AMP)¿ and total adenine nucleotides (TAN) from (ATP + ADP + AMP). After the biopsy the aorta was cannulated for blood sampling.

RESULTS

Rats in each group were similar in weight, as well as acid base and blood gas status just after liver biopsy. Hepatic energy charge, ATP, ADP, AMP, and TAN levels were not different in animals receiving either halothane, isoflurane or enflurane when compared with those receiving only oxygen.

CONCLUSION

One MAC of anesthesia for a period of 2 hours with the described volatile anesthetic agents did not affect adenine nucleotide status in vivo in rats.

Alterations in porcine gastric mucin during the development of experimental ulceration

Bile duct ligation in the pig results in ulceration of the pars oesophagea (oesophagogastric junction) within 48 h with 100% reproducibility. This work describes novel observations made during development of such ulcers using an endoscope introduced at intervals postoperatively via a Thomas gastric cannula. Macroscopic and histological changes were recorded and compared with quantitative and qualitative changes in crude mucus scrapings and purified mucins. Crude mucus scrapings of the cardiac gland region had a higher protein content in the ulcerated states than in the normals. After bile duct ligation, the (degraded) mucin glycopeptide/total protein ratio was higher in partially purified mucus from pre-ulcerated and ulcerated stomachs as compared with normal samples. The quantity of purified mucin was less in samples from ulcerated stomachs, and the N-acetylgalactosamine and fucose contents were also decreased. It is possible that these changes resulted in the failure of the mucus barrier and the development of oesophagogastric junction ulceration.

Early effects of total hepatectomy on haemodynamic state and organ uptake of catecholamines in the pig

In a previous study, we showed that plasma concentrations of catecholamines were increased during the anhepatic phase in pigs. In this study, we investigated if a constant depth of anaesthesia would prevent these changes and, if not, if the changes were caused by impaired extraction of catecholamines. We measured arterial and venous pressures, heart rate and cardiac output in 10 anaesthetized pigs. Hepatic arterial and portal venous flows were measured. Blood for measurement of catecholamines was sampled from carotid and pulmonary arteries and portal, hepatic and renal veins. After a 2-h observation period, the liver was removed and the circulation reconstituted. Measurements were made and samples obtained for another 2 h. Catecholamine concentrations increased 2-10-fold after hepatectomy. Before hepatectomy, noradrenaline was extracted by the lung (mean extraction ratio 23 (SEM 8)%) and the liver (30 (11)%); after hepatectomy, there was extraction by the kidney (24 (12)%) but extraction by the lung (29 (8)%) was unchanged. Before hepatectomy, adrenaline was extracted predominantly by the kidney (73 (5)%) and the liver (70 (6)%), with minimal extraction by the lung; after hepatectomy, extraction by the lung increased (25 (4)%) and decreased slightly in the kidney (56 (6)%). While mean arterial pressure did not change, heart rate increased by approximately 50% and cardiac index declined (ns) within 2 h after hepatectomy. There was a sharp increase in pulmonary vascular resistance after removal of the liver and changes correlated with increases in arterial plasma concentrations of catecholamines.

Alcohol pretreatment does not affect bupivacaine pharmacokinetics in the pig

We investigated whether alcohol pretreatment sufficient to cause fatty liver change would affect the disposition of bupivacaine after i.v. administration in pigs. Twelve male pigs (22-26 kg) were randomly divided into two groups of six each. Group A received ethanol (1 g kg-1 day-1) via an intragastric tube for 16 days. Group D received an equal volume of isocaloric dextrose 44% in water for this period. On day 17, left internal jugular and carotid cannulae were placed under thiopentone anaesthesia. On recovery from anesthesia, a blood sample was taken for the determination of liver function indices and then bupivacaine hydrochloride (1.2 mg kg-1) was administered over one minute and samples for plasma bupivacaine analysis taken from the arterial cannulae over the next five hours. Right liver lobe biopsies were taken and animals were killed under general anaesthesia. Blind evaluation of liver biopsies confirmed fatty liver changes only in alcohol-pretreated livers. Despite this there were no differences in bupivacaine disposition and liver function indices between the two groups.

Haemostatic and immunological sequelae of portacaval shunt in rats

We have evaluated the link between haemostatic abnormalities and immune dysfunction in liver disease by evaluating parameters of cellular and humoral immunity in conjunction with coagulation profiles in rats following portacaval anastomosis, induction of portal hypertension by portal vein stenosis or by sham surgical procedures. Twelve weeks following surgery, portacaval shunted rats were markedly anaemic (8.9 +/- 0.6 g/dl; controls 12.3 +/- 1.4 g/dl, p < 0.05), had low plasma fibrinogen levels (0.6 +/- 0.3 g/l, controls 2.5 +/- 0.2 g/l p < 0.05) and markedly elevated fibrin(ogen) degradation products (FDP) titres (1/40-1/80; controls < 1/10. p < 0.05). Portal vein stenosed rats were less anaemic (11.5 +/- 0.8 g/dl), had near normal fibrinogen levels (2.1 +/- 0.3 g/l) but elevated FDP levels (1/40-1/80). Both portacaval shunted and portal vein stenosed rats had elevated serum IgG levels (35.1 +/- 14.1 g/l; 29.2 +/- 13.9 g/l respectively; control values 20 +/- 5.9 g/l p < 0.05 for comparison with both experimental groups). Intrinsic lymphocyte proliferation to T and B cell mitogens was markedly depressed in the portacaval anastamosed rats when compared to controls. Serum factors inhibitory to control lymphocyte proliferation were noted in the shunted rats. Phagocytosis of complement and immunoglobulin sensitised sheep RBC by Kupffer cells purified from rats that had undergone portacaval shunting was markedly reduced (p < 0.05). The increased degree of phagocytosis following exposure to LPS-endotoxin (50 micrograms/ml) was proportionate in degree to the control group. Spontaneous release of bioactive lymphocyte activating factors (IL-1 and IL-6) by purified rat sinusoidal cell populations was decreased in the portacaval shunted group, and decreased still further following stimulation with LPS (50 micrograms/ml) in vitro. The observation that many of the haemostatic and immunological abnormalities associated with chronic liver disease are present in rats with surgically created portacaval shunts or with induced portal hypertension, lends credence to the hypothesis that shunting of portal blood is, at least in part, responsible for many of the systemic manifestations associated with chronic liver disease.

Substance P level is increased in the cholesterol induced anaphylactoid reaction in the pig

The role of substance P (SP) in cholesterol-induced anaphylactoid reaction was investigated in 13 Landrace pigs. Pigs were anesthetized with sodium thiopental and ventilation was controlled with 70% nitrous oxide in oxygen. A Swan-Ganz catheter and a carotid arterial line were placed to monitor the hemodynamic data. Group 1 pigs (control group, n = 5) each received 20 ml of intravenous (IV) colloid infusion solution (Haemaccel) and group 2 pigs (cholesterol group, n = 8) each received an IV injection of pure cholesterol emulsion (12 mg/kg) in 20 ml of Haemaccel. Blood samples for SP and histamine (H) levels were taken just before and for 10 min following the placebo, Haemaccel, and cholesterol injections. Urine samples were also collected just before and at 60 min following the injections for methyl histamine (MH) levels. Group 2 pigs (cholesterol) developed an anaphylactoid reaction as indicated by marked and significant hemodynamic changes. None of the group 1 (placebo) pigs developed an anaphylactoid reaction. Significant increases in blood SP and H levels (P < 0.05), and urine MH levels (P < 0.05) were seen in cholesterol-treated pigs (group 2), whereas no significant changes were seen in control pigs (group 1). Our results suggest that SP is involved in the cholesterol-induced anaphylactoid reaction in pigs.

Investigating the reliability and validity of the infrared tympanic thermometer: a learning experience

This series of articles to date has discussed points that readers should be looking for when reading and critiquing a researcher article. This article presents a brief report of a research project investigating the reliability and validity of the infrared tympanic thermometer (ITT) in afebrile subjects. Using four subjects and 40 temperature diads, the ability of the ITT to predict the subjects' temperatures obtained with a mercury thermometer was very poor (regression coefficient = .39). Test-retest reliability using the same data set resulted in an equally poor correlation coefficient (r = .19). A critique of the methodology of the study is provided as a learning experience.

Regeneration after in situ flushing of partially hepatectomised rat livers

The effect of various components of the transplant procedure upon the regenerative process in reduced liver grafts is not known. In this study, partially hepatectomised rat liver remnants were flushed with 5 ml of either Ringer's lactate, Euro Collins solution or University of Wisconsin solution at 4 degrees C and then 5 ml Ringer's lactate at 4 degrees C. After partial hepatectomy alone, the peak increase in thymidine kinase was measured at 24 hours (36,021 +/- 8,060 disintegrations per minute per milligram protein; the mitotic index was 25 +/- 7). In all the groups in which the remnant was flushed, peak thymidine kinase and mitotic index were measured at 48 hours. The pattern of ornithine decarboxylase activity was disorganised in all groups. Flushing of the liver remnant therefore delays the regenerative response by 24 hours. In large animals, including humans, regeneration appears to commence within the first 5 days after resection. A comparable delay doubling this time might coincide with the onset of rejection and further compromise liver function.

Hepatic blood flow during reduced liver grafting in pigs. A comparison of controls and recipients of intact allografts

Intraoperative changes in portal venous and hepatic arterial flow were compared in porcine recipients of reduced liver grafts with recipients of intact grafts and sham-operated controls. Control animals showed no significant changes in hepatic blood flow (measured with perivascular ultrasonic cuffs), heart rate, mean arterial pressure, cardiac output, acid/base balance, plasma sodium, potassium, glucose, or catecholamines. Recipients of intact or reduced grafts showed hypotension, reduced cardiac output, tachycardia, and increased systemic vascular resistance during the anhepatic phase, which lasted approximately 30 min. These changes returned to normal in recipients of intact grafts but in recipients of reduced grafts, levels returned only to 50-60% of baseline. After intact grafting, total liver blood flow and the portal and arterial components returned to baseline within 2 hr of revascularization, but after reduced grafting, hepatic arterial flow values remained depressed to 50-60% of baseline. Plasma epinephrine and norepinephrine were unaltered during control operation but increased 4- to 20-fold in recipients of all grafts. These returned towards baseline in all except recipients of reduced grafts, in which norepinephrine levels remained significantly elevated for the 4 hr of postoperative study. These data highlight persistent elevation of plasma norepinephrine after reduced liver grafting, which may have contributed to the diminished hepatic arterial flow. These results need to be confirmed in adult recipients of split liver grafts in whom grafts are comparatively small. In such patients receiving donor livers which have undergone prolonged storage, the effects of increased plasma norepinephrine levels upon donor agonal arterial spasm may be significant.

Transposition of the antropylorus for anal incontinence--an experimental model in the pig

An experimental model in the pig rendered incontinent of feces was developed to assess the sphincteric activity of the transposed antropylorus. In the control group, normal defecation was studied clinically, radiologically, and manometrically. Nineteen 7- to 10-week-old pigs were rendered incontinent by resection of 20 cm of colon and rectum to below the dentate line. The antropylorus was prepared on its own blood supply and transposed to the anus, initially with a colostomy, which was closed 15 to 21 days later. Clinically these pigs passed semisolid stool in a piecemeal fashion. Contrast defecography showed hold-up at the pylorus, reflux of contrast into the colon, with pyloric contraction independent of antral stimulation. Manometry showed pyloric contraction with rise in antral pressure and independence. The authors conclude that transposition of an antropyloric segment to the anus provides a sphincter-like mechanism and could have application in fecal incontinence.

The influence of flow and hematocrit on the laser Doppler flux signal from the surface of the perfused pig liver

OBJECTIVE

We tested the hypothesis that the measurement volume of the laser Doppler flowmeter (LDF) is too small to provide reliable quantitative estimates of total liver blood flow of large mammals, such as the pig.

METHODS

In a perfused pig liver, the influence of changing (i) hepatic arterial (HA) and portal venous flows individually (n = 9), (ii) HA flow at fixed portal venous flow (50%, 70%, and 100% expected total liver blood flow), and (iii) hematocrit (0-30%) at fixed total liver blood flow on LDF flux was tested (n = 8).

RESULTS

Linearity of LDF with hepatic arterial flow and portal venous flow was confirmed; however, the slope of the regression lines was higher for hepatic artery [1.92 +/- 0.60 (SD)] than portal vein perfused livers (0.66 +/- 0.34; P < 0.001). With portal venous flow at 50% and 70% total liver blood flow, changing hepatic arterial flow produced linear LDF versus flow responses, but at 100% total liver blood flow, linearity was achieved in only 6/9 livers. The coefficient of variation for the slopes of regression lines was always > 30%. At constant total liver blood flow (100 ml/min per 100 g), LDF response decreased linearly by a factor of about 2 on changing the hematocrit from 30% to 5% and markedly fell as the hematocrit was further decreased to zero.

CONCLUSIONS

These results suggest that (i) the LDF flux signal from the liver surface provides a poor measure of hepatic microcirculatory blood flow during changes in total liver blood flow as the LDF responds with about three times greater sensitivity to changes in hepatic arterial than in portal venous flow, and (ii) when hematocrit is falling, LDF may underestimate hepatic perfusion to a significant extent. In addition, due to high measurement variability, the LDF flux signal cannot be quantified in absolute perfusion units.

Lidocaine extraction by the in vivo and isolated perfused pig liver

Hepatic lidocaine elimination is increasingly being used to assess hepatic function. Although the isolated liver is extensively used as a model of in vivo function, it is necessary to determine whether this is a suitable model for in vivo lidocaine elimination. Fourteen male pigs (22-25 kg) were divided into two groups. Seven were anesthetized, and catheters and perivascular flow probes placed for transhepatic sampling and hepatic arterial and portal venous flow measurement. Sampling was performed at hourly intervals to determine hepatic function and plasma composition. Hepatic lidocaine elimination was determined during the second hour of a lidocaine infusion (1.41 mg.kg-1.min-1 for 10 min, then 0.165 m.kg-1.min-1), during which time the mean hepatic blood flow rates, plasma acid base status and body temperature were measured so that these could be emulated in the isolated perfused liver experiments. Seven male pigs were then anesthetized and the liver resected and cannulated for isolated liver perfusion. Hepatic arterial and portal venous blood flow and perfusate temperature were set to the mean in vivo values, and hepatic function and perfusate composition assessed at corresponding times. Hepatic lidocaine elimination was determined at a similar hepatic inflow whole blood concentration (+/- 5 micrograms.ml-1) to that in vivo over the second hour of lidocaine administration (40 mg bolus, then 2.8 mg.min-1). Lidocaine extraction ratio in vivo (0.61 +/- 0.04) [mean +/- SEM] and ex vivo (0.63 +/- 0.02) was similar, as was hepatic blood clearance (381 +/- 70 vs 363 +/- 16 ml.min-1) and hepatic blood intrinsic clearance (1132 +/- 280 vs 1069 +/- 109 ml.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of hepatectomy and plasma cholinesterase inhibition on cocaine metabolism and cardiovascular responses in pigs

To determine the effects of total hepatectomy and inhibition of plasma cholinesterase activity on cocaine metabolism, we measured plasma concentrations of cocaine and its three major metabolites, benzoylecgonine, ecgonine methyl ester, and norcocaine, by high-performance liquid chromatography in three groups of male pigs. Pigs were anesthetized with sodium thiopental and lungs were ventilated with nitrous oxide in oxygen. A right carotid arterial cannula and an internal jugular venous catheter were then inserted for the administration of cocaine and for blood sampling. A Swan-Ganz catheter was inserted through the right internal jugular vein. Group 1 pigs underwent sham operation; group 2 and 3 pigs underwent hepatectomy and portocaval shunt. In addition, group 3 pigs were treated with tetraisopropyl pyrophosphoramide, a specific plasma cholinesterase inhibitor. After this preparation, pigs were given 4 mg/kg cocaine intravenously over 2 minutes. After cocaine injection, 4 ml blood was collected into heparinized test tubes containing 2.5% sodium fluoride for determination of cocaine and its metabolites at 2, 5, 10, 15, 30, 45, 60, 90, 120, 180, 240, and 300 minutes. We also measured hemodynamic responses after cocaine administration, including heart rate and rhythm, cardiac output, and arterial blood pressure. Data were analyzed by analysis of variance. Blood levels of cocaine and its metabolites were significantly different among the three groups (p < 0.05 by analysis of variance). Our results show that total hepatectomy was associated with a marked slowing of cocaine metabolism, absence of norcocaine, and increased benzoylecgonine levels when compared with the baseline values in the control pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytoskeletal actin: the influence of major burns on neutrophil structure and function

It has been noted that major trauma and burns patients who survive beyond 48 h most frequently succumb to sepsis and multiple organ failure. Furthermore, such patients are usually markedly hypermetabolic and in negative nitrogen balance at the time of their demise. Along with many other systemic and immune dysfunctions, the polymorphonuclear white blood cells in this setting become functionally impaired. Given that the motile white blood cells contain significant proportions of the contractile protein, actin, we speculated that the leucocyte dysfunction might in part be related to the overall systemic catabolism of actin stores. Accordingly, this hypothesis was explored by comparing the functions and cytoskeletal structure of neutrophilic leucocytes from normal control adults and victims of fresh, major thermal injuries. On days 1 and 7 after a burn of > 25 per cent of total body surface area, peripheral blood was drawn from 10 patients (mean age 33 years, mean burn area 44.2 per cent), and seven unburned controls (mean age 35.2 years). Neutrophils isolated from these specimens were tested for stimulated chemotactic rate, efficacy of intracellular killing as determined by superoxide production rate, and the levels of soluble and insoluble intracellular actin. In addition, both light microscopy and scanning electron microscopy were used to visualize the actin cytoskeleton. The results indicated that both chemotactic rate (12 mu/min vs. 38 mu/min--P < 0.05) and superoxide production rate (9 vs 43 mumol/ml10E6 cells--P < 0.05), were significantly reduced in the burn patients by day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol pretreatment alters the metabolic pattern and accelerates cocaine metabolism in pigs

We investigated whether alcohol pretreatment would affect the disposition and metabolic pattern of intravenously (i.v.) administered cocaine in pigs. Six pigs (Group A) received alcohol (1 g/kg/day) and six pigs (control; Group D) received an equal volume of isocaloric dextrose 44% in water for 10 days via an intragastric tube. On day 11, arterial samples were taken for five hours following an intravenous administration of cocaine hydrochloride (4 mg/kg). Plasma concentrations of cocaine and its major metabolites were analyzed by HPLC method. Significant decrease in plasma half-life (10 +/- 1.2 vs. 18.7 +/- 1.4 min), and significant increases in apparent volume of distribution (73 +/- 6 vs. 51 +/- 31) and clearance (5.37 +/- 0.6 vs. 1.82 +/- 0.1 l/min) were seen in alcohol pretreated pigs as compared with control pigs (P < 0.05). Significant increases in plasma concentrations of benzoylecgonine (P < 0.05), and insignificant differences in ecgonine methyl ester and norcocaine levels were seen between the two groups. Neither ecgonine nor cocaethylene was detected in the blood samples. Our data show that alcohol administration for ten days accelerated the elimination of i.v. administered cocaine and altered its metabolic pattern in pigs.

The effect of administration of FK506 on delayed regeneration in flushed partially hepatectomized livers

It has been shown previously that liver regeneration after partial hepatectomy in rats is delayed if the liver is subjected to either concurrent ischaemia, flushing with cold solution, or grafting. We have shown recently that treatment with CsA preoperatively overcomes the suppressive effect of flushing and returns the regenerative response to a normal time scale. The present study was designed to investigate whether administration of FK506 would also return the observed delayed regenerative response to normal. Long-Evans rats weighing 250-350 g were subjected to standard 68% partial hepatectomy. Group 1 had no further treatment; in group 2, the liver remnant was flushed with 10 ml cold (4 degrees C) Ringers lactate solution, and in group 3, FK506 (1 mg/kg/day) was administered by intramuscular injection for 3 days before the partial hepatectomy and flushing as in group 2; a final dose was given after completion of the procedures. Animals were killed in sets of 6 per group at 4, 24, 48, 72, and 96 hr after surgery and blood samples were taken for measurement of plasma aspartate amino-transferase. Liver biopsies were analyzed for measurement of thymidine kinase and ornithine decarboxylase activity and for counting of mitotic figures. While the highest recorded thymidine kinase activity occurred in group 1 at 24 hr, this was delayed to 48 hr in both group 2 and 3 and counts remained high up to 96 hr in group 3. Mitotic indices were only significantly elevated (compared with group 1 at 96 hr), while ornithine decarboxylase activity did not correlate with these changes being significantly lower than in groups 2 and 3 at 4 hr and in group 3 also at 24 hr. Plasma aspartate aminotransferase was also significantly higher in group 3. It is concluded that the administration of FK506 preoperatively to rats subjected to partial hepatectomy and flushing did not restore the delayed regenerative response to normal but enhanced the response (as measured by thymidine kinase but not by mitotic indices) which commenced at 48 hr and was still present at 96 hr.

Does liver transplantation in the rat cause a regenerative response. The effect of arterialisation of the graft

This study was conducted to determine the pattern of early regenerative response to orthotopic intact liver transplantation in the rat and to investigate whether the response differed in grafts with or without revascularisation of the arterial bed. Outbred male Long Evans (LE-LE allogeneic, non rejector) rats weighing 300-350g were subjected to orthotopic intact liver allograft using a "sleeve" anastomosis for the hepatic artery. Total warm ischaemia ranged from 19 to 34 minutes and no storage was employed. Comparison was made with a group of control rats which were subjected to 25 minutes total inflow occlusion and regeneration was measured with tissue thymidine kinase (TK) and mitotic figures. Samples were taken at 1, 2, 4, 7, 10 and 20 days post-operatively. Plasma aspartate aminotransferase (AAT) and light microscopy were used to evaluate hepatocyte necrosis. There was a brief sharp increase in TK and AAT in the first 24 hours after sham operation but no appearance of mitotic figures. A similar but more prolonged increase in TK occurred in the arterialized transplant group with the highest levels recorded on day 4. The level remained significantly elevated above pre-operative until 10 days and declined within 20 days. Mitotic figures appeared at 2 days, reached significance at 7 and 10 days and had disappeared by 20 days. The pattern of changes was accentuated in animals in which the artery was not reanastomosed and the increases in TK and AAT were still significant at 20 days. Whilst similar degrees of peri-portal cellular infiltrate occurred in both groups of rats, bile duct proliferation was most obvious in non-arterialized animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of lidocaine on in vivo hepatic function

Lidocaine is administered to assess donor or recipient liver function during hepatic transplantation. This study was performed to determine whether lidocaine administered at a constant concentration affected hepatic function or had demonstrable effects on hepatocellular ultrastructure. Fourteen pigs were randomly allocated to receive either a two-stage infusion of lidocaine hydrochloride or of saline. Transhepatic blood samples were taken and ultrasonic portal venous and hepatic arterial blood flow readings made on animals anesthetized with isoflurane in nitrous oxide. Liver biopsies were taken for histological analysis and determination of adenine nucleotide status prior to and after 2 hr of the two-stage infusion. A mean systemic constant plasma lidocaine concentration of 5.9 micrograms/ml was achieved during the second hour of infusion. There were no differences between the two groups in a large number of indices of hepatic function and plasma composition prior to and during the second hour of the respective infusions. Hepatic blood flow was also similar at these times. On histological examination there were no electron microscopic changes that could be specifically attributed to the administration of lidocaine. However, there were progressive changes with time. This study suggests that in anesthetized pigs a constant lidocaine concentration of about 6 micrograms/ml has no detrimental effect on hepatic function. Progressive hepatic ultrastructural changes occurred that could not be attributed to the administration of lidocaine. These may be the result of anesthetic administered or the surgery performed.

Effect of flushing of the liver graft upon plasma calcium and magnesium concentrations

Previous studies of total and ionized calcium in the plasma of liver transplant recipients have been conducted in patients with preexisting liver disease or who received blood transfusion. The intraoperative decline in plasma total and ionized calcium has been attributed to the effects of liver disease and/or the citrate in transfused blood. The present study was conducted in normal porcine recipients of liver stored either with EuroCollins or University of Wisconsin (UW) solution for 6 hr, compared with livers flushed with Ringer's lactate without storage. No blood transfusion was given. Mean total plasma calcium levels declined significantly after storage with UW solution to a nadir approximately 65-70% of preoperative levels. This decline persisted for two to five days. Mean levels of plasma ionized calcium declined lowest after flushing with UW solution but only to 82% of preoperative (NS). There was an increase in plasma total magnesium in the recipients of livers flushed with EuroCollins or UW solutions, which resolved within 30 min and which was probably related to magnesium content of the flushing solution. It is concluded that while the changes in plasma total and ionized calcium are moderate and of little clinical significance, they could be aggravated under clinical conditions by massive blood transfusion. Changes in plasma magnesium seemed to be directly attributable to the magnesium content of flushing solutions but the same relationship did not exist for changes in plasma calcium.

The effects of inhibition of plasma cholinesterase activity on systemic toxicity and blood catecholamine levels from cocaine infusion in pigs

We investigated systemic effects and possible mechanisms for lethality of intravenously infused cocaine in spontaneously breathing and mechanically ventilated unconscious Landrace male pigs weighing about 26 kg (25.75 +/- 0.25 kg) that were pretreated with either saline solution (groups 1 and 3) or iso-ompa (tetraisopropyl pyrophosphoramide), a specific plasma cholinesterase inhibitor (groups 2 and 4). Pigs were made unconscious with sodium thiopental and ventilated with 70% nitrous oxide and 30% oxygen. A carotid arterial cannula and a Swan-Ganz catheter were inserted for hemodynamic monitoring. Pigs in groups 1 and 2 were then allowed to breathe spontaneously and groups 3 and 4 were mechanically ventilated. After obtaining a stable state, as judged by cardiovascular and respiratory parameters, the pigs were infused intravenously with cocaine hydrochloride (0.8 mg/kg/min) until the time of cardiac arrest. Respiratory and cardiovascular parameters, blood temperature, and sodium and potassium levels were monitored. The times of occurrence of respiratory arrests (RA), cardiac arrests (CA), and convulsions were recorded. Our results showed that RA is the primary cause of death in spontaneously breathing pigs and that mechanical ventilation significantly delayed the occurrence of CA (p < 0.05). Significant decreases in cardiac output, mean blood pressure, and heart rate as well as significant increases in systemic and pulmonary vascular resistances, central venous and pulmonary wedge pressures, and blood K+ levels were noted in mechanically ventilated pigs (p < 0.05). Variable hemodynamic responses were noticed in spontaneously breathing pigs. Our results also showed that no significant changes occurred in blood catecholamine levels when compared with baseline values associated with the infusion of toxic doses of cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Is full-time surgical research a career for a woman?

In this review of a 25-year experience in full time surgical research, special emphasis is placed on the suitability of such a post for a female surgeon and on the particular skills that a woman can bring to such a position.

Effect of hypoxia on the hepatic metabolism of lidocaine in the isolated perfused pig liver

The metabolism of lidocaine to monoethylglycinexylidide has been found useful as an indicator of liver function in association with liver transplantation. It has been postulated that this is due to the common effect of hypoxic damage on liver function and lidocaine metabolism. The effects of hypoxia on the elimination of lidocaine and the formation of monoethylglycinexylidide and on indexes of liver function were investigated with the isolated perfused pig liver preparation. This study was performed at similar hepatic effluent lidocaine concentrations of approximately 5 micrograms.ml-1 in normoxic (n = 7) and hypoxic (n = 8) livers of similar mass harvested from male Landrace x Large White pigs and perfused at standard unit hepatic flow rates. Whole blood lidocaine extraction ratio was 0.63 +/- 0.02 in normoxic livers (30% O2 at oxygenator inflow). It was significantly less (0.23 +/- 0.03) in livers subjected to hypoxia (2% O2 at oxygenator inflow), as were hepatic clearance (57.1 +/- 2.1 vs. 20.3 +/- 3.1 ml.min-1.100 gm-1), intrinsic clearance (1,706 +/- 182 vs. 284 +/- 53 ml.min-1.100 gm-1) and monoethylglycinexylidide formation as indicated by monoethylglycinexylidide/lidocaine ratios in the hepatic venous effluent (0.379 +/- 0.061 vs. 0.073 +/- 0.014) (p < 0.01). Hepatic oxygen consumption, adenine nucleotide status and bile flow were significantly impaired by hypoxia. Whereas perfusate potassium concentration increased early, AST levels showed delayed increases and ALT levels showed no changes. These changes correlated strongly with hepatic lidocaine elimination (p < 0.01). We conclude that lidocaine metabolism may be an early indicator of severe hepatic hypoxia.