Effects of calcium channel blocking agents on calcium and centrilobular necrosis in the liver of rats treated with hepatotoxic agents.

Carbon tetrachloride, chloroform, dimethylnitrosamine, thioacetamide or acetaminophen was each administered to rats in a single hepatotoxic dose. Nifedipine, verapamil or chlorpromazine was administered in association with the hepatotoxic agents to determine if calcium channel blocking agents would prevent an increase in liver cell calcium associated with hepatotoxicity and to determine if these agents would protect against the development of centrilobular necrosis. Following a latent period different for each toxic agent, a 4- to 18-fold increase in liver cell calcium content had occurred by 24 hr. The calcium increase and the centrilobular necrosis (mean histologic score) were correlated. A relatively high calcium to necrosis ratio was obtained with dimethylnitrosamine, thioacetamide and acetaminophen. A lesser calcium to necrosis ratio was obtained with chloroform and carbon tetrachloride, the two toxic agents that destroyed the intracellular calcium sequestration activity of the liver endoplasmic reticulum. Nifedipine or chlorpromazine, administered prior to and 7 hr after the toxic agent, completely prevented the centrilobular necrosis caused by thioacetamide, carbon tetrachloride and acetaminophen; almost completely prevented necrosis with dimethylnitrosamine; and provided partial protection against chloroform toxicity. Two doses of verapamil provided partial protection against necrosis when carbon tetrachloride was the toxic agent and provided almost complete protection with dimethylnitrosamine. A reduction in liver cell calcium was associated with the protective action of the three calcium channel blocking agents. These findings are compared with earlier studies of the protective effects of calcium channel blocking agents in cardiac ischemia.

Effects of calcium channel blocking agents on membrane microviscosity and calcium in the liver of the carbon tetrachloride treated rat.

Membrane microviscosity was determined from the polarized fluorescence of diphenylhexatriene in plasma membranes and microsomes prepared from the liver of carbon tetrachloride treated rats. It was greatly depressed between 12 and 24 hr after the administration of the carbon tetrachloride. Depression of microviscosity was also seen in the liposomes which were prepared from these membranes. There were decreases in phospholipid content and phospholipid methyltransferase activity, but these changes did not appear to explain the decreased microviscosity. A large accumulation of calcium occurred in the liver cells between 12 and 24 hr after the administration of carbon tetrachloride. Chlorpromazine, verapamil and nifedipine, when administered prior to the carbon tetrachloride, partially reduced the later accumulation of calcium and reduced the degree of histological damage observed. When these agents were administered 12 hr after the administration of carbon tetrachloride, they did not reduce the subsequent accumulation of calcium. When administered prior to and 7 hr after carbon tetrachloride, they had a small but potentially significant effect on the microviscosity change. It is suggested that at low levels of microviscosity a critical threshold may exist below which entry of calcium into the cell is poorly controlled and that calcium channel blocking agents may be ineffective if administered at a time when membrane microviscosity is very low. Tissue calcium accumulation was associated with visible cell damage.

Maternal tobacco smoking and changes in amino acid uptake by human placental villi: induction of uptake systems, gammaglutamyltranspeptidase and membrane fluidity.

Maternal smoking depressed the active uptake of amino acids by human placentae and lowered their levels in the placenta and umbilical vein. During starvation of cells for amino acids, more amino acid carriers are induced and incorporated into the plasma membrane. A question arises whether there could be similar changes due to maternal smoking in the placental amino acid uptake carrier systems. Therefore, the characteristics of (a) the uptake of 2-amino[I-14C]-isobutyric acid (AIB) by isolated placental villi, (b) gammaglutamyltranspeptidase (GGTP), a critical enzyme of the gammaglutamyl cycle (GGC) for the uptake of amino acids in human placenta, and (c) lipid structural parameters (reciprocal of fluidity), by steady state fluorescence polarization of plasma membrane vesicles of microvilli (MV) and microsomal membranes (MM) of umbilical and chorionic plate arteries of placentae of smoking and non-smoking mothers were investigated. The above investigations gave the following results: (a) Washed placental villi of smokers exhibited higher capacity for AIB uptake than those of non-smokers. The higher uptake capacity was mainly due to increase in Vmax for AIB uptake in smokers. Km increased for placental AIB uptake in smokers. (b) Maternal smoking lowered GGTP activity of MV by decreasing its Vmax. Therefore, maternal smoking decreases the formation of gammaglutamyl-amino acid (GGAA) on the surface of trophoblast which are absorbed by the trophoblast. The degree of absorption of GGAA is considered as an inverse environmental signal for the cell to regulate amino acid transport systems. Maternal smoking seems to decrease the formation and absorption of GGAA and thereby induce the formation of new carriers for AIB uptake. (c) Maternal smoking increased the values for lipid structural order parameters and microviscosity of MV and induced tolerance against fluidization by ethyl alcohol in MM of umbilical and chorionic arteries. The alterations could increase Km for AIB uptake system and decrease the sensitivity of umbilical and chorionic arteries to vasoconstrictive substances like 5-hydroxytryptamine and catecholamine which are released by nicotine. All these changes tend to overcome the deficits produced in placental amino acid transport and satisfy the demands of the growing fetus for amino acids.

CNI-1493 attenuates hemodynamic and pro-inflammatory responses to LPS.

The increased production of pro-inflammatory cytokines and nitric oxide have been postulated to contribute to the deleterious sequella of LPS administration. To date, clinical strategies to control these responses using individual specific inhibitors have been disappointing. The aim of the present study was to determine whether a tetravalent guanylhydrazone compound (CNI-1493) attenuates LPS-induced stress responses by suppressing multiple inflammatory mediators. Rats were injected intravenously with either CNI-1493 (10 mg/kg) or vehicle (1 mL NaCl) 60 min prior to the injection of LPS (100 microg/100 g body weight). LPS produced a 20% decrease in mean arterial blood pressure and a significant increase in circulating TNF-alpha levels as well as in tissue content of TNF-alpha, IL-1beta, and IL-6. This was associated with a marked increase in lung and gut apoptosis and myeloperoxidase (MPO) activities as well as with an increase in lung and spleen nitric oxide end products (NOx). Pretreatment with CNI-1493 attenuated the LPS-induced drop in mean arterial blood pressure (MABP) and blunted (40%) the rise in circulating TNF-alpha levels. CNI-1493 attenuated the LPS-induced increase in tissue cytokine (TNF-alpha, IL-1beta, and IL-6) content in lung and spleen but did not alter that of liver or gut. CNI-1493 pretreatment protected both lung and gut from LPS-induced apoptosis and in addition attenuated the rise in MPO activity in the gut. These results suggest diverse effects of CNI-1493 that are tissue specific and that confer protection against the hemodynamic and inflammatory responses to LPS.

Immunoreactive substance P in human saliva. A possible marker of chronic pain.

In all patients and volunteers, the levels of immunoreactive SP measured in saliva were about 100 times higher than the levels measured in plasma. SP per mg protein was consistently lower in both plasma and saliva of chronic pain patients than in healthy volunteers. These findings suggest that a simple noninvasive objective method of determining SP in saliva may become useful in the evaluation and treatment of chronic pain.

The effect of procainamide on plasma cholinesterase activity.

The in vitro effect of procainamide on plasma cholinesterase (PCHE) activity in the plasma of ten normal ASA physical status I patients was studied using a kinetic method. The mean plasma cholinesterase activity without procainamide (control) was 0.90 +/- 0.09 units.ml-1. The dibucaine numbers of all the samples were in the normal range of 78 to 86, indicating normal genotypes. The mean plasma cholinesterase activity, in the presence of procainamide in concentrations of 5.0, 10.0, 20.0 and 40.0 micrograms.ml-1, was reduced to 0.73 +/- 0.04, 0.61 +/- 0.03, 0.45 +/- 0.02, and 0.36 +/- 0.01 units.ml-1, respectively. At therapeutic concentrations of 4 to 12 micrograms.ml-1, procainamide inhibited cholinesterase activity 15 to 30 per cent. The authors also showed that the concentration of procainamide required to inhibit 50 per cent of plasma cholinesterase activity was 20 micrograms.ml-1 (I50). The authors conclude that procainamide when tested in vitro had a statistically significant depressant effect on plasma cholinesterase activity at all the concentrations studied.

Inhibition of pseudocholinesterase activity protects from cocaine-induced cardiorespiratory toxicity in rats.

We studied the effect of inhibition of pseudocholinesterase by a specific pseudocholinesterase inhibitor, tetraisopropyl pyrophosphoramide (ISO-OMPA) on the cardiorespiratory toxicity of intravenously injected cocaine in rats. Group 1 rats received ISO-OMPA subcutaneously, whereas group 2 rats received saline placebo subcutaneously. Thirty minutes later, rats were anesthetized with 40 mg/kg of sodium pentobarbital intraperitoneally and were then given 10 mg/kg (least toxic dose) cocaine intravenously. Thirty minutes after the first injection of cocaine, about half of the rats that survived from each group were given 12 mg/kg cocaine (low toxic dose) intravenously, and the other half was given 13.5 mg/kg cocaine (high toxic dose) intravenously. Five minutes after each injection, rats were classified as either survivors or fatalities. In group 1 (ISO-OMPA treated), five of 29 (17%) rats that received 10 mg/kg cocaine, two of 11 (19%) that received 12 mg/kg cocaine, and three of 13 (24%) that received 13.5 mg/kg cocaine died of cardiorespiratory toxicity. In group 2 (saline treated), two of 29 (7%) that received 10 mg/kg cocaine, six of 12 (50%) that received 12 mg/kg cocaine, and 10 of 15 (67%) that received 13.5 mg/kg cocaine died of cardiorespiratory toxicity (p less than 0.03). Pseudocholinesterase activity (mean +/- SEM) of groups 1 and 2 were 0.6 +/- 0.2 and 7.3 +/- 0.7 units, respectively (p less than 0.01). Our results show that rats with lower pseudocholinesterase activity had lower fatality rates than rats with higher pseudocholinesterase activity.

Immunoreactive substance P is decreased in saliva of patients with chronic back pain syndromes.

Substance P, a neuropeptide associated with pain perception, is widely distributed in the central nervous system and is decreased in the cerebrospinal fluid of chronic pain patients as compared with that of healthy human volunteers. In this study, we have demonstrated the presence of immunoreactive substance P in saliva and further, that both saliva and plasma levels of immunoreactive substance P are lower in patients with chronic low back pain than in healthy human volunteers. To our knowledge, this is the first time that substance P has been identified in human saliva. These findings, together with the noninvasive nature of saliva collection, suggest that substance P in saliva may be useful as an alternative neurochemical correlate of chronic low back pain when collection of cerebrospinal fluid and plasma samples for substance P analysis is unacceptable or inappropriate.

The effects of neurokinin A, neurokinin B, and eledoisin on substance P analysis.

Commercial sources for neuropeptide radioimmunoassays have made this sensitive tool available to clinical investigators for monitoring the potential involvement of neuropeptides in pain modulation. We measured substance P-like immunoreactivity in the plasma, saliva, and pericardial fluid of subjects with and without pain (chronic and acute) to determine if substance P levels are altered. Some recent studies have suggested that substance P in various body fluids may be a correlate of chronic pain. To test this correlation it is important to ensure that the assay is measuring what it was designed to measure. Therefore, the influence of three tachykinins on the analysis of substance P concentrations was assessed with a commercially available radioimmunoassay kit. A small (approximately 2 to 6%), apparently nonspecific elevation in measured substance P was found when alpha-neurokinin, beta-neurokinin, or eledoisin was incubated with substance P and its antibody. Our results also indicate an apparent specific affinity of the substance P antibody for alpha-neurokinin (above 1,000 pg/ml) and beta-neurokinin (above 5,000 pg/ml). Substance P levels in the body fluids we tested ranged from 0.47 to 62.88 pg/mg protein (47.4 to 230.8 pg/ml). Levels of the tested tachykinins have not been determined in body fluids. If alpha-neurokinin or beta-neurokinin is found to be present in high concentrations in these fluids, this commercially available substance P kit may overestimate substance P levels. The concentrations of tachykinins necessary to interfere specifically with the assay are 10- to 100-fold higher than substance P in body fluids.(ABSTRACT TRUNCATED AT 250 WORDS)

Cimetidine-carbaryl interaction in humans: evidence for an active metabolite of carbaryl.

The influence of cimetidine on the pharmacokinetic and pharmacodynamic response to the insecticide carbaryl has been investigated in isolated human erythrocytes (red blood cells; RBC) and after oral administration of 1 mg/kg carbaryl to four normal subjects in the absence or presence of cimetidine (300 mg, 8/hr for 3 days). Carbaryl induced a concentration-dependent reduction of isolated RBC acetylcholinesterase activity requiring 1 microgram/ml to achieve 20% inhibition. Cimetidine also induced a dose-dependent inhibition of RBC acetylcholinesterase activity, but at 40-fold higher concentrations. At high concentrations, cimetidine was additive to carbaryl-induced inhibition of RBC acetylcholinesterase, but exhibited no effect at the therapeutically relevant concentrations (10 micrograms/ml). After oral carbaryl administration to normal subjects, plasma concentrations rapidly rose to a peak, then declined with a half-life of 0.79 +/- 0.47 hr. Oral carbaryl clearance was 5.4 +/- 2.0 l/min. Peak plasma carbaryl concentrations were associated with 27% inhibition of RBC acetylcholinesterase activity, and the concentration associated with a reduction of RBC acetylcholinesterase activity of 20% was 0.02 microgram/ml. The terminal half-life for the dynamic response was 2.6 +/- 1.5 hr. After pretreatment with cimetidine, peak plasma carbaryl concentrations doubled and clearance was reduced (to 2.5 +/- 1.5 l/min) (P less than .05). However, half-life remained unchanged. Despite increased carbaryl levels, the maximum inhibition of RBC acetylcholinesterase activity was significantly reduced, and the concentration of carbaryl required to achieve 20% inhibition of RBC acetylcholinesterase activity was increased to approximately 0.5 microgram/ml. These results are consistent with the hypothesis that carbaryl is metabolized by drug-metabolizing enzymes that can be inhibited by cimetidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary artery catheter introducers: do the component parts affect flow rate?

Arrow sheath introducers are useful during massive transfusion as well as during catheter insertion. However, each component (sheath, side port, and obturator/catheter) probably progressively impedes maximum flow. This study quantitates these flow changes. Six configurations (C) were tested: (C1) sheath; (C2) sheath, side port; (C3) sheath, side port, obturator; (C4) C3 with 1.5-in obturator; (C5) C3 with 0.25-in obturator; (C6) no components. Flow was measured five times with each configuration and compared. Flows (mL/min) (mean +/- SE) were: (C1) 838.1 +/- 11.2, (C2) 283.4 +/- 9.2, (C3) 149.9 +/- 7.9, (C4) 176.0 +/- 14.0, (C5) 232.5 +/- 5.5, (C6) 1030.5 +/- 11.6. Flow decreased progressively with C2 and C3 (P less than 0.0001). C4 did not increase flow, but C5 did (P less than 0.0001). C5 flow was comparable to C2 but less than C1 (P less than 0.0001). C6 flow was larger than any other configuration (P less than 0.0001). Flow increases in C2 and C5 over C3 and C4 were modest (25%-50%) compared with C1 (250%). Therefore, we do not recommend removing or cutting the obturator to improve flow. During massive transfusion, we recommend removal of the side port until smaller flows suffice.

Role of the kidney in plasma glucose regulation during hyperglycemia.

Little is known about the role of the kidney in plasma glucose regulation during hyperglycemia. We studied 12 overnight-fasted conscious dogs after either intrarenal (IR, n = 6) or peripheral (PH, n = 6) dextrose infusion to maintain hyperglycemia without glycosuria. Systemic and renal glucose kinetics were measured with [6-3H]glucose, lactate balance was measured by arteriovenous difference, and glycogen content was assayed in the kidneys. Plasma glucose (approximately 5.5 vs. approximately 6.3 mM), insulin (approximately 70 vs. approximately 110 pM), and glucose appearance (approximately 14 vs. approximately 16 mumol.kg-1.min-1 increased comparably in both groups (P < 0.05). In IR, fractional extraction of glucose (FEGlc) increased from 4.1 +/- 0.2 to 16.1 +/- 0.5% (P < 0.001) and lactate balance reversed to renal output (+1.3 +/- 0.2 vs. -0.9 +/- 0.2 mumol.kg-1.min-1, P < 0.01). Glycogen content was twofold higher in the left (127 +/- 33 micrograms/g tissue) than in the right kidney (56 +/- 11 micrograms/g tissue, P < 0.01). In PH, FEGlc decreased from 4.9 +/- 0.6 to 2.2 +/- 0.3% (P < 0.05), renal glucose utilization did not change (approximately 1.3 mumol.kg-1.min-1); and glycogen content was equal in both kidneys (approximately 45 micrograms/g tissue). We conclude that, although the kidney plays a minor role in plasma glucose disposal in physiological hyperglycemia, increased glucose uptake, glycogen storage, and lactate formation precede glycosuria and may represent important mechanisms by which the kidney contributes to normalization of plasma glucose in diabetes.

Relationships between chemical structure and inhibition of choline acetyltransferase by 2-(alpha-naphthoyl)ethyltrimethylammonium and related compounds.

A choline acetyltransferase (ChA) inhibitor with an optimum combination of properties of potency, stability and membrane permeability is required to study several functional aspects of acetylcholine in nervous and non-nervous tissues. Therefore, 2-(alpha-naphthoyl)ethyltrimethylammonium iodide (alpha-NETA), 2-(beta-naphthoyl)ethyltrimethylammonium iodide (beta-NETA), 2-(9'-anthroyl)ethyltrimethylammonium iodide (9'-AETA) and their corresponding tertiary dimethylamine hydrochloride analogs (alpha-NEDA, beta-NEDA, 9'-AEDA) were synthesized and tested for their ChA inhibitory activities. The quaternary ammonium compounds were more potent inhibitors (150 in microM: alpha-NETA, 9; beta-NETA, 76; 9'-AETA, 32) than the corresponding tertiary compounds (150 in microM: alpha-NEDA, 63; beta-NEDA, 1400; 9'-AEDA, 77). The alpha-naphthyl moiety was preferable to the beta-naphthyl- or 9'-anthryl moieties for alignment with the enzyme for inhibition. alpha-NETA and alpha-NEDA exhibited adequate ChA inhibitory potencies for further pharmacological studies and localization of membrane bound ChA. They exhibited fluorescent characteristics of the alpha-naphthyl moiety. Their ChA inhibition was not reversible by dialysis. They were considerably more potent for inhibiting ChA than cholinesterases and carnitine acetyltransferase.

Differential responses of brain, liver, and muscle glycogen to opiates and surgical stress.

We examined the effects of intracerebroventricular (ICV) cannula implantation followed by the administration of morphine sulfate (MOR) and its metabolite, morphine-6-glucuronide (M6G), on the glycogen content of the brain, liver, and muscle. ICV cannulation resulted in nearly a 30% reduction in brain glycogen, and ICV MOR resulted in a 36% reduction in liver glycogen content compared to time-matched controls, but it had no additional effect on either the brain or muscle glycogen content. ICV M6G showed a more significant reduction, to 50% of liver glycogen, but it had no effect on either brain or muscle glycogen. Neither IV MOR nor M6G produced any significant alteration in tissue glycogen content. These results indicate that the stress response associated with neurosurgery, especially the placement of the ICV cannula, is associated with a decrement in brain glycogen. The activation of opioid receptors in the brain results in enhanced hepatic glycogenolysis but has no additional effect on the brain glycogen content.

Blood leukocyte and glutamine fluctuations after eccentric exercise.

Skeletal muscle, as a producer of glutamine, is important for lymphocytes, monocytes and macrophages. Exercise-induced muscle damage could burden the immune system by concurrently eliciting a local inflammatory response and decreasing glutamine availability. The aim of this study was to determine whether blood leukocyte and glutamine concentrations were affected in individuals with high serum creatine kinase (CK) activity (indirect indication of muscle damage) compared to those with no change in CK. Twelve females performed maximal eccentric resistance exercise using one arm and one leg. Blood leukocyte subsets and glutamine were measured at 24 and 0 h pre-exercise, and post-exercise at intervals up to 9 d post-exercise. Eleven subjects were placed in High (n = 6) and Low CK (n = 5) groups. Lymphocytes, (total, natural killer, and T), monocytes, and granulocytes did not change significantly in either group, at any time. Whole blood glutamine concentration decreased (p < 0.05) from 437 microM pre-exercise to 332 microM 3 d post-exercise in both groups. The decrease in glutamine suggests that the metabolism of the muscle may be affected by this exercise, however, the occurrence of this decrease in both groups suggests that this change was not a response to muscle damage.

Substance P, acetylcholinesterase, and beta-endorphin levels in the plasma and pericardial fluid of patients with and without angina pectoris.

We measured substance P-like immunoreactivity (SPLI), beta-endorphin-like immunoreactivity (BELI), acetylcholinesterase activity, and total protein content in pericardial fluid and plasma of patients with angina pectoris and patients with no angina pectoris. SPLI and BELI levels, acetylcholinesterase activity, and total protein content were determined by radioimmunoassay, a colorimetric method, and by the method of Lowry et al. (J Biol Chem 1951; 193:265-75), respectively. In the pericardial fluid, patients with angina had SPLI, BELI, acetylcholinesterase, and total protein values of 1.69 +/- 0.23 fmol/mg protein, 0.16 +/- 0.13 fmol/mg protein, 0.06 +/- 0.02 units, and 25.7 +/- 3.2 mg/ml, respectively. Patients with no angina had SPLI, BELI, acetylcholinesterase, and total protein values of 0.93 +/- 0.17 fmol/mg protein, 0.19 +/- 0.10 fmol/mg protein, 0.16 +/- 0.02 units, and 44.6 +/- 5.3 mg/ml, respectively. SPLI levels were significantly higher (p less than 0.03), and acetylcholinesterase (less than 0.002) and total protein content (less than 0.004) were significantly lower in the pericardial fluid of patients with angina when compared with those of patients with no angina. BELI levels were not significantly different between the two groups. In the plasma, no significant differences were found in SPLI, BELI, acetylcholinesterase, and total protein values between the two groups of patients. Patients with angina had SPLI, BELI, acetylcholinesterase, and total protein values of 0.47 +/- 0.26 fmol/mg protein, 0.06 +/- 0.06 fmol/mg protein, 0.29 +/- 0.15 units, and 68.2 +/- 8.7 mg/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The inhibitory effect of metoclopramide on plasma cholinesterase activity.

The in vitro effect of metoclopramide on plasma cholinesterase (PCHE) activity was studied to investigate a mechanism for metoclopramide-induced prolongation of succinylcholine action. The mean PCHE of the control samples was 0.86 +/- 0.02 unit.ml-1. PCHE activity in the presence of metoclopramide, at concentrations of 0.05, 0.10, 0.50, 1.0, 2.5 and 5.0 micrograms.ml-1, was reduced to 0.78 +/- 0.02, 0.69 +/- 0.04, 0.50 +/- 0.03, 0.39 +/- 0.02, 0.24 +/- 0.01 and 0.15 +/- 0.01 unit.ml-1, respectively. Our data demonstrated that PCHE activity was significantly depressed by metoclopramide at all concentrations studied (p less than 0.001). Our data also show that the concentration of metoclopramide required to inhibit 50 per cent of PCHE activity (I50) was 0.8 micrograms.ml-1 (2.4 x 10(-6) M). We recommend caution when succinylcholine and or ester type local anaesthetics are administered to patients who are also receiving metoclopramide, especially in high doses.

Modulation of endogenous opiate production: effect of fasting.

The endogenous opiate alkaloid content in tissues from fed, 24 h and 48 h fasted rats was determined. Plasma morphine and codeine concentrations did not change in response to fasting. Morphine levels in the spleen increased 3-fold after 24 h of fasting and were lower than fed rats by 48 h of fasting; no change was detected in spleen codeine levels. Brain morphine levels were elevated 5-fold after 24 h of fasting and were two-fold higher than those of fed rats after 48 h of fasting. Brain codeine levels did not change with fasting. These results indicate that opiate alkaloids are endogenously produced in rodent tissues, particularly in the spleen, liver, and adrenals. The synthesis of morphine, in the spleen and brain, is maximally stimulated after 24 h of fasting, without alterations in tissue codeine synthesis. These suggest differential regulation of the endogenous synthetic pathways of morphine and codeine in response to the stress of fasting.

Early organ-specific hemorrhage-induced increases in tissue cytokine content: associated neurohormonal and opioid alterations.

Hemorrhage is associated with an impairment in the immune response and with increased concentrations of circulating inflammatory cytokines. The present study determined the time course and localization of alterations in circulating and tissue pro-inflammatory cytokines (TNF-alpha, IL-1-alpha and -beta) in response to fixed-pressure (40 mm Hg) hemorrhage as well as the associated hanges in circulating neurohormonal and opioid mediators. Conscious unrestrained non-heparinized male Sprague-Dawley rats (n = 24) underwent hemorrhage followed by standard resuscitation with lactated Ringer's solution. Animals were sacrificed at three time points; immediately after the hemorrhage period, at completion of resuscitation and 1.5 h after the resuscitation period. Hemorrhage resulted in marked elevations in circulating levels of TNF-alpha, which averaged 860 +/- 201 pg/ml. The levels were similarly elevated following fluid resuscitation (877 +/- 196 pg/ml) and had decreased towards baseline 1.5 h after completion of resuscitation (281 +/- 134 pg/ml). TNF-alpha was not detectable in plasma of time-matched controls. Hemorrhage elevated TNF-alpha content in spleen (25%), lung (55%) and heart (20%), and tissue content remained elevated despite resuscitation. No significant changes in tissue content of TNF-alpha were detected in the liver, kidney or brain. Circulating levels of IL1-alpha and -beta were not detectable in either the time-matched controls or hemorrhaged animals. However, statistically significant elevations in tissue content of IL-1 alpha were observed in heart, spleen, lung, gut and whole brain (15-30%). Tissue content of IL-1 beta did not change in response to hemorrhage and/or fluid resuscitation. Activation of sympathetic outflow, as evidenced by a 3- to 4-fold elevation in circulating epinephrine and norepinephrine levels, was observed immediately after hemorrhage, and was associated with a 5-fold rise in circulating beta-endorphin. These results demonstrate an early increase in tissue cytokine content following hemorrhagic shock, which is associated with elevations in circulating catecholamines and endogenous opioids, consistent with their potential modulatory role in this response.

In vitro effects of fluoride and bromide on pseudocholinesterase and acetylcholinesterase activities.

The in vitro effects of two metabolites of inhalational anaesthetics, fluoride and bromide, on pseudocholinesterase (PCHE) and acetylcholinesterase (ACHE) activities in the blood samples of seven healthy patients were studied. The PCHE and ACHE activities were determined by kinetic spectrophotometric methods. Fluoride at the levels achieved with clinical concentrations of enflurane and sevoflurane (25-75 microM.L-1) inhibited PCHE activity by 28-65 per cent (P less than 0.01) and ACHE activity by less than five per cent (P greater than 0.05). Bromide at the levels achieved with clinical concentrations of inhalational anaesthetics had no significant effect on either PCHE or ACHE activity. We recommend caution when succinylcholine and/or ester type local anaesthetics are used in the immediate postoperative period following enflurane or sevoflurane anaesthesia. We also recommend that blood drawing for PCHE activity be delayed at least until 24 hr following enflurane or sevoflurane anaesthesia.