Effects of acute hypotensive hemorrhage on arginine vasopressin gene transcription in the rat brain

To determine whether hypotensive hemorrhage has an effect on arginine vasopressin (AVP) gene expression, 16 ml/kg of arterial blood was drawn over 10 min in conscious unrestrained rats. Mean arterial blood pressure (MABP) and heart rate (HR) were measured, and the rats were decapitated before and 10 min, 1, 3, 6, 9, 12, and 24 h after the initiation of hemorrhage. The hypothalamic or cerebro-hypothalamic tissue was used to measure AVP mRNA by Northern blot analysis, and the trunk blood to measure plasma AVP, osmolality and hematocrit. Hemorrhage brought about rapid and transient decreases in MABP and HR accompanied by transient increases in plasma osmolality and AVP. Hematocrit decreased after the bleeding and reached a stable level 6 h after hemorrhage and thereafter. AVP mRNA was detected in the hypothalamus and not in the extrahypothalamic cerebral brain tissue under basal and posthemorrhage conditions. AVP mRNA in the cerebro-hypothalamic tissue increased by 1.8-fold at 6 h and 2.1-fold at 9 h after hemorrhage. These results indicate that AVP mRNA in the brain increases 6 h after increased AVP release in response to hypotensive hemorrhage.

A comparison of two immediate-early genes, c-fos and NGFI-B, as markers for functional activation in stress-related neuroendocrine circuitry

The promoter regions of the rat corticotropin-releasing factor (CRF), oxytocin (OT), and vasopressin (AVP) genes contain sequences similar to the cis-acting response element identified for NGFI-B, an immediate-early gene structurally related to the steroid hormone receptor superfamily. Combined immuno- and hybridization histochemical approaches were used to determine whether challenges that influence the synthesis and secretion of CRF, OT, and/or AVP result in altered expression in neurosecretory neurons of NGFI-B and another immediate-early gene, c-fos, which is widely used as a marker for functionally activated neurons. NGFI-B mRNA was found to be expressed at constitutively high levels in the telencephalon, but not in the endocrine hypothalamus, of unperturbed controls; basal levels of c-fos expression were uniformly low throughout the CNS. NGFI-B and c-fos mRNAs, and Fos protein, were induced with a similar time course and in similar neuroendocrine cell types in response to acute hypotensive hemorrhage (15% reduction in blood volume), intravenous injection of interleukin-1 beta (IL-1 beta; 1.87 micrograms/kg), chronic salt loading (7 d maintenance on 2% saline), and acute bilateral adrenalectomy. c-fos mRNA and Fos protein were readily demonstrable in afferent pathways that have been implicated as mediating the neuroendocrine responses in the three stress paradigms; these include medullary catecholaminergic cell groups in response to IL-1 beta and hemorrhage, and cell groups lining the lamina terminalis in response to salt loading. Challenge-specific induction of NGFI-B expression was detectable in these extrahypothalamic cell groups, though with a lesser sensitivity than that required to reveal NGFI-B induction in the hypothalamus, or c-fos expression in these related afferents. These results establish NGFI-B as a useful adjunct to c-fos, for revealing synaptic and/or transcriptional activation in the magno- and parvocellular neurosecretory systems. Differences in the sensitivity of the two markers in revealing functionally related activation in extrahypothalamic regions speak to general issues concerning the use of immediate-early genes in mapping functional circuitry in the CNS.

Changes in the hepatic oxygenation state during hemorrhage and following epinephrine or dextran infusion as assessed by near-infrared spectroscopy

Changes in the hepatic oxygenation state of rabbits during hemorrhage and subsequent epinephrine (n = 6) or dextran infusion (n = 6) were assessed by tissue near-infrared spectroscopy. Oxygen saturation of hemoglobin in the liver (hepatic SO2), and redox transition of cytochrome aa3 were analyzed by applying multicomponent analysis to the absorption spectrum of the liver. Hepatic SO2, representing extracellular oxygenation state, decreased from 62.4 +/- 2.7% (mean +/- SEM) to 21.1 +/- 7.3% after bleeding. It increased to 31.8 +/- 6.6% after epinephrine infusion, but returned to near-control levels after dextran infusion. Intracellular oxygenation state as assessed by the changes in the oxidized and reduced forms of cytochrome aa3 was impaired after bleeding, and remained as such even after epinephrine infusion. By contrast, it was normalized to near control levels after dextran infusion. Changes in the difference of hepatic SO2 and hepatic venous SO2 suggested that the intrahepatic blood flow was more heterogeneously distributed after bleeding, but that the heterogeneity of microcirculation was rather diminished after epinephrine infusion.

Alteration in regional brain catecholamines during and after acute hemorrhage in the rat

Using high-performance liquid chromatography (HPLC), we carried out a simultaneous assay of norepinephrine (NE), epinephrine (E), and dopamine (DA) in specific brain regions before and at 5 min, 30 min, 1 hr, 2 hr, and 24 hr following acute hemorrhage in the rat. Thirty-six awake male Sprague-Dawley rats were subjected to rapid fixed-volume hemorrhage (8.5 ml/300 g) over 5 min. In the hypothalamus, concentrations of NE and E fell markedly and significantly by 5 min posthemorrhage (P < 0.001), while hypothalamic DA concentrations fell gradually to reach a nadir by 2 hr (P < 0.005). Hypothalamic concentrations of all three catecholamines remained significantly reduced up to 24 hr posthemorrhage. Dopamine concentrations in the medulla increased transiently, while striatal DA concentrations fell following hemorrhage to reach a nadir by 2 hr (P < 0.001). By 2 hr posthemorrhage, NE concentrations in both cortex and medulla were significantly decreased (P < 0.01 and P < 0.005, respectively), with cortical NE levels remaining significantly depressed for up to 24 hr. These results suggest that regional and prolonged changes occur in central catecholaminergic systems following acute, uncompensated hemorrhage. It is possible that these changes in the central nervous system contribute to the cardiovascular dysfunction observed following hemorrhage.

Effects of hemorrhage on cytokine gene transcription

Injury and blood loss are often followed by infection and the rapid development of organ system dysfunction, frequently involving mucosal sites, such as the lung and intestine. To examine possible mechanisms contributing to these conditions, we used semiquantitative polymerase chain reactions to determine cytokine mRNA expression among cellular populations isolated from mucosal and systemic anatomic sites of mice at predetermined time points following 30% blood volume hemorrhage with resuscitation 1 hr later. Within 1 hr after hemorrhage, significant increases were observed in mRNA levels for IL-1 alpha, IL-1 beta, IL-5, and TGF-beta in intraparenchymal pulmonary mononuclear cells. The levels of TGF-beta transcripts among alveolar macrophages were increased 1 hr following blood loss, and increase in IL-1 alpha transcripts was found starting 2 hr posthemorrhage. Cells from Peyer's patches showed significant increases in mRNA levels for IL-1 beta, IL-2, IL-5, IL-6, IFN-gamma, and TGF-beta during the 4 hr following hemorrhage. Significant increases in mRNA levels for IL-1 beta, TNF-alpha, and TGF-beta were present within 4 hr of blood loss among cells isolated from mesenteric lymph nodes. The expression of mRNA for most cytokines was not significantly altered in splenocytes or peripheral blood mononuclear cells at any time point following hemorrhage. These experiments demonstrate that blood loss, even if resuscitated, produces significant increases in proinflammatory and immunoregulatory cytokine gene transcription as early as 1 hr following hemorrhage. These posthemorrhage alterations in cytokine mRNA expression were particularly prominent at mucosal sites, suggesting a mechanism for the increased incidence of pulmonary and intestinal involvement in organ system failure following severe blood loss and injury.

Role of beta 2 integrins and ICAM-1 in lung injury following ischemia-reperfusion of rat hind limbs

Ischemia/reperfusion involving the hind limbs of rats results in both local injury to skeletal muscle as well as injury to lungs, as measured by increased vascular permeability (125I-labeled bovine serum albumin leakage) and hemorrhage (extravasation of 51Cr-labeled rat erythrocytes). In the current study, we have focused on events in lungs occurring during reperfusion of hind limbs. Analysis of blood neutrophils obtained 4 hours after reperfusion has indicated up-regulation of CD11b and CD18 but not CD11a. Plasma from the same animals demonstrate the ability to induce similar effects in normal blood neutrophils, indicative of the presence of a neutrophil-activating agent in plasma. During reperfusion, lung injury, which develops progressively over a 4-hour period, has been shown to be neutrophil-dependent and requires CD11a/CD18 and CD11b/CD18 as well as intercellular adhesion molecule-1. These data suggest that ischemia and reperfusion injury of rat lower extremities causes systemic changes that result in neutrophil-dependent lung injury that is beta 2 integrin- (leukocyte function antigen-1, Mac-1) and intercellular adhesion molecule-1-dependent.

Requirements for tumor necrosis factor-alpha and interleukin-1 in limb ischemia/reperfusion injury and associated lung injury

Ischemia in rat hind limbs followed by reperfusion results in local as well as remote organ (lung) injury characterized by increased vascular permeability (125I-labeled bovine serum albumin leakage) and hemorrhage (51Cr-labeled rat erythrocytes extravasation) in skeletal muscle and lung, together with an associated increased tissue content of myeloperoxidase, reflecting neutrophil accumulation. Within 60 minutes of reperfusion following ischemia, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and IL-6 plasma levels increased significantly, reaching maximum levels after 2 hours of reperfusion. Polyclonal antibodies to TNF-alpha and IL-1 provided significant protection against vascular injury in both muscle and lung. These results were confirmed by the use of soluble TNF-alpha receptor and IL-1 receptor antagonist. In rat lungs following ischemia and reperfusion, there was immunohistochemical evidence of E-selectin expression in the lung vasculature; this expression was blocked by treatment of animals with anti-TNF-alpha. These data indicate that both local (hind limb) and remote (lung) organ injury after ischemia/reperfusion requires participation of TNF-alpha and IL-1. The cytokines may, in part, be involved in the up-regulation of endothelial adhesion molecules.

Influence of hematocrit on tissue O2 extraction capabilities during acute hemorrhage

This study was performed to test the hypothesis that tissue O2 extraction capabilities during hemorrhage may be greater when hematocrit (Hct) is initially reduced. Twenty-four anesthetized and splenectomized dogs were randomly assigned in three groups of eight dogs each: group 1 (Hct 40), 40-45% Hct; group 2 (Hct 30), 30-35% Hct; and group 3 (Hct 20), 20-25% Hct. In each animal, the desired Hct was obtained by normovolemic hemodilution using hydroxyethyl starch 450/0.7 and maintained throughout the experiment. O2 delivery (DO2) was progressively reduced by hemorrhage. At each step, DO2 and O2 consumption (VO2) were measured separately. Critical DO2 obtained from a plot of VO2 vs. DO2 was lower in the Hct 30 and Hct 20 groups than in the Hct 40 group [(in ml.min-1.kg-1) Hct 30, 7.9 +/- 2.2; Hct 20, 7.8 +/- 1.0; Hct 40, 10.4 +/- 1.1; P < 0.05]. Critical DO2 obtained from blood lactate levels was also significantly lower in the Hct 30 and Hct20 groups than in the Hct 40 group. Critical O2 extraction ratio was also greater in the Hct 30 and Hct 20 groups than in the Hct 40 group (Hct 30, 73.0 +/- 13.9%; Hct 20, 70.1 +/- 9.6%; Hct 40, 57.1 +/- 11.5%; P < 0.05). In the conditions of our study, moderate hemodilution was associated with an improvement of the O2 extraction capabilities of the body, probably related to the reduction in blood viscosity.

Prostacyclin regulates splanchnic blood flow during early hemorrhage/reperfusion injury

The effect of oxygen radicals on superior mesenteric artery (SMA) blood flow and splanchnic prostaglandin release was examined during early hemorrhage/reperfusion injury. Sprague-Dawley rats were hemorrhaged to 30 mm Hg for 5, 10, or 15 min without (SK5, SK10, and SK15) or with (SK10+R, and SK15+R) blood reperfusion. The SK15+R group were treated with or without superoxide dismutase (SOD 10 000 units/kg intravenously). In vivo SMA blood flow was measured continuously for 100 min by a transonic flow probe. The in vitro-perfused superior mesenteric artery and end organ intestine (SV+SI) were assayed for release of 6-keto-PGF1 alpha, thromboxane B2 (TXB2) and PGE2 by radioimmunoassay. Acute hemorrhage for 10 and 15 minutes increased SV+SI 6-keto-PGF1 alpha release 2-fold and 10-fold respectively compared to the sham (p < 0.01), which was abolished by blood reperfusion. SMA blood flow was decreased by 4% and 60% in the SK10+R and SK15+R groups respectively compared with the sham (p < 0.01). SOD treatment restored both SV+SI release of 6-keto-PGF1 alpha and SMA blood flow to control levels in the SK10+R and SK15+R groups. Oxygen-derived free radicals produced within 15 min of acute hemorrhage/reperfusion injury inhibited splanchnic PGI2 synthesis, which contributed to decreased splanchnic blood flow.

Diagnostic significance of nailfold bleeding in scleroderma spectrum disorders

BACKGROUND

The early detection of scleroderma spectrum disorders (SSD) is important.

OBJECTIVE

Our purpose was to determine the prevalence of nailfold bleeding in SSD.

METHODS

We examined patients for nailfold bleeding in the following three groups: (1) 81 patients with SSD including 50 patients with scleroderma, 10 with mixed connective tissue disease, and 21 with Raynaud's phenomenon having specific antinuclear antibody (ANA); (2) 99 patients with other connective tissue diseases or primary Raynaud's phenomenon; and (3) 200 patients with common skin diseases.

RESULTS

The frequency of nailfold bleeding was significantly higher in SSD (75.3%) than in other connective tissue diseases (12.1%) and in controls (3.0%). The presence of nailfold bleeding in two or more fingers showed a 98.3% specificity for SSD. Among the patients with SSD, the incidence of nailfold bleeding in scleroderma, mixed connective tissue disease, and Raynaud's phenomenon with specific ANA was similar. Nailfold bleeding strongly correlated with the presence of anticentromere antibody.

CONCLUSION

The presence of nailfold bleeding is useful for the early detection of SSD.

Lactate in rat skeletal muscle after hemorrhage measured by microdialysis probe calibrated in situ

The interstitial lactate concentration in rat skeletal muscle was measured in the normal state and after hemorrhage using a microdialysis probe, and the values calculated by in vitro and in vivo calibration were compared. After withdrawal of 30% of the estimated total blood volume, the lactate concentration in the dialysate gradually increased and then maintained an almost constant level. It was found that interstitial lactate levels of skeletal muscle calculated by the in vitro calibration method were not significantly different from those calculated by in vivo calibration in both the normal state and after hemorrhage. These data indicate that the absolute lactate concentration in the muscle interstitium in the normal state and after acute hemorrhage can be practically measured by a microdialysis probe calibrated in vitro. From the comparison of lactate concentrations in blood and in the muscle interstitium, it was suggested that rat skeletal muscle functions as a lactate consumer, rather than as a lactate producer, after acute hemorrhage.

Anesthetic influences on myocardial and hepatic energy metabolism in hemorrhaged spontaneous hypertensive rats

Twenty four spontaneously hypertensive rats (SHRs) were used to assess the influence of anesthetics on myocardial and hepatic energy metabolism after hemorrhage. They were divided into four groups: a control group and three others which received pentobarbital (60 mg.kg-1 ip), 2.2% enflurane, or 1.4% isoflurane. Following a 10-min stabilisation period, blood (2 ml.100 g body weight-1) was gradually withdrawn over a 5-min period from a femoral artery. Thirty minutes after the induction of hemorrhage, the heart and liver were removed, and myocardial and hepatic metabolites (ATP, lactate, pyruvate, and glycogen) were measured by the enzymatic methods. Metabolic acidosis and decreased hematocrit were noted in all groups after hemorrhage. The mean arterial pressure in rats receiving anesthetics decreased significantly in comparison with the control group. There were significant increases of myocardial and hepatic lactate/pyruvate ratios in rats receiving enflurane when compared with controls. These results suggest that enflurane may be more detrimental than other anesthetics to the maintenance of anesthesia in hypovolemic SHRs.

Renal innervation plays no role in oxygen-dependent control of erythropoietin mRNA levels

To assess the role of renal innervation in O2-dependent control of erythropoietin (EPO) formation, we have determined EPO mRNA levels in both kidneys of unilaterally denervated rats and sham-operated controls using RNase protection. To investigate whether possible effects of renal nerve input are related to the type of hypoxic stimulus and the degree of stimulation, animals were studied under basal conditions, after exposure to normobaric hypoxia (8% O2, 4 h) or CO (0.1%, 4 h), and after acute hemorrhage (decrease in hematocrit from 40.8 +/- 0.5 to 12.7 +/- 0.5% within 7 h; mean +/- SE, n = 6). Serum EPO levels rose on average 22-, 49-, and 48-fold under the three stimuli and were unaffected by unilateral denervation. Renal EPO mRNA levels in unilaterally denervated animals, when expressed in arbitrary units revealed by comparison with an external standard, were 7.0 +/- 1.5 vs. 6.3 +/- 2.0 (normoxia), 432 +/- 136 vs. 451 +/- 156 (normobaric hypoxia), 971 +/- 93 vs. 930 +/- 120 (CO), and 604 +/- 170 vs. 689 +/- 203 (hemorrhagic anemia) in the intact vs. the denervated kidney (mean +/- SE, n = 3). Furthermore, there was no difference between EPO mRNA levels of either kidney of unilaterally denervated animals and levels in sham-operated controls. We conclude that renal nerve input plays no significant role in the control of the EPO gene under both basal and stimulated conditions.

Increase in renal magnesium overflow following aortotomy-induced hemorrhage in pigs

Hemorrhage causes an increase in plasma Mg++ levels. This article identifies some of the tissues contributing to the hemorrhage induced increase in plasma Mg++. Anesthetized, splenectomized pigs were subjected to a 5 mm aortotomy. Blood samples from the abdominal aorta, inferior vena cava, pulmonary artery, hepatic portal vein, and renal vein were sampled for Mg++ changes caused by this uncontrolled hemorrhage. Aortotomy produced a rapid drop in arterial pressure and cardiac output, both of which remained depressed for the following 120 minutes (P less than 0.05). By 120 minutes, 6 of the 8 pigs survived, but three of the six survivors showed signs of cardiovascular decompensation. A significant increase in arterial plasma Mg++ was indicated by a paired t-test (P less than 0.05). Analysis of the venous samples also revealed a significant increase during the post-aortotomy period. Renal venous and hepatic portal venous plasmas both showed increases greater than that in the arterial plasma. The renal and splanchnic tissues, then, were partly responsible for the increase in the arterial Mg++ which follows hemorrhage.

Feedback modulation of renal and hepatic erythropoietin mRNA in response to graded anemia and hypoxia

Erythropoietin (EPO) mRNA levels were measured by ribonuclease (RNase) protection in organs from unstimulated rats and from animals after normobaric hypoxia or hemorrhagic anemia. Both liver and kidney responded to stimulation with large increases in EPO mRNA, but the response characteristic to graded stimulation was different. The liver responded poorly to mild normobaric hypoxia, accounting for only 2 +/- 1% of total EPO mRNA at 11% O2, but hepatic EPO mRNA levels increased steeply with more severe hypoxia so that at 7.5% O2 the liver contributed to 33 +/- 7% of the total. After hemorrhagic anemia, the liver also responded more strongly to more severe stimulation, but at all points it accounted for a significant proportion of total EPO mRNA, contributing 18 +/- 6% after removal of 2.5 ml (hematocrit 37.2 +/- 1.3%), increasing to 37 +/- 14% after venesection of 10.5 ml (hematocrit 15.8 +/- 0.8%). Studies of EPO mRNA in other organs confirmed that EPO production outside the liver and kidney were quantitatively insignificant in stimulated animals. However, the hypoxia-induced increases in EPO mRNA in brain, testis, and spleen suggest the existence of an oxygen-sensing mechanism at other sites.

[Effect of dibunol on lipid peroxidation and alpha-tocopherol level in the rat heart in acute hemorrhage]

The authors studied the effect of a single injection of dibunol in a dose of 120 mg/kg on lipid peroxidation (LPO) and alpha-tocopherol (TP) level in the heart muscle in acute blood loss. The LPO products and alpha-tocopherol level were determined simultaneously in a heart homogenate 2 hours after the blood loss. It was established that the loss of blood leads to activation of LPO and reduction of the TP level in the myocardium. Dibunol injection inhibited LPO activation, reducing the content of LPO products to that in animals with a false operation (without blood loss), and increased the TP level also to that in a false operation. The decrease of the TP level in acute blood loss depends, evidently, on increased mobilization of TP from the myocardium due to the increased level of catecholamines (CA), while the increase of TP under the effect of dibunol occurs due to its inhibited mobilization from the myocardium, which is mediated by reduction of the CA level.

Relationship of thrombohemorrhagic complications to endothelial cell function in patients with chronic myeloproliferative disorders

Thrombotic and hemorrhagic disorders are common complications of the myeloproliferative disorders. Endothelial cells release both procoagulant and profibrinolytic factors, which may contribute to these hemorrhagic or thrombotic complications. The pre- and postvenous stasis levels of the procoagulant and profibrinolytic factors produced by endothelial cells were correlated with the occurrence of complications in polycythemia rubra vera (PRV) patients (n = 29) and essential thrombocythemia (ET) patients (n = 17) compared with normal patients (n = 17). Tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor (PAI) activity, von Willebrand's factor (vWF) activity and antigen (vWF:Ag), and factor VIII activity were measured. The resting tPA activity was significantly higher in the two disease groups compared with normal controls, but no difference between the levels of tPA and either complication within the disease groups was observed. Significantly elevated tPA following venous stasis was observed in the patients of both disease groups who had bleeding complications. Significant decreases, compared with the normal group, in both resting and postvenous stasis levels of PAI were observed in the disease groups regardless of complication history. The subjects from both disease groups with thrombotic complications had significantly elevated resting vWF and both resting and postvenous stasis vWF:Ag levels compared with normal controls. The endothelial cell is likely to be responding to abnormal hemostasis rather than being primarily involved in the genesis of a hyper- or hypocoaguable state.

Continuous measurement of lactate concentration in skeletal muscle and liver interstitium using a microdialysis method after acute hemorrhage in anesthetized rats

Interstitial lactate concentration in rat skeletal muscle was continuously measured using a microdialysis method following an acute hemorrhage. For comparison, similar measurements were also performed for liver. Normal lactate levels of skeletal muscle and liver interstitium were 0.58 +/- 0.10 mM and 1.23 +/- 0.04 mM, respectively. After withdrawal of 30% of the estimated total blood volume within 3 min, a constant high blood lactate level was achieved. The lactate concentrations in muscle and liver interstitium also increased to 270 and 210% of the basal levels, respectively, but they did not exceed the blood level. These findings led us to hypothesize that skeletal muscle as well as liver functions as a lactate consumer rather than a producer after acute hemorrhage.

Distribution of hypothalamic, medullary and lamina terminalis neurons expressing Fos after hemorrhage in conscious rats

The immunohistochemical detection of the protein, Fos, has been used as an anatomical marker of activated neurons. Three conscious rats were hemorrhaged (4 ml, 20-25% of blood volume) and the distribution of Fos-stained neurons was compared to that in 4 rats which did not have blood removed. In hemorrhaged rats, a higher concentration of Fos-stained neurons was present in the lamina terminalis, particularly the subfornical organ and organum vasculosum of the lamina terminalis, and in the supraoptic and paraventricular nuclei of the hypothalamus. In the medulla, Fos-stained neurons were restricted to the nucleus of the tractus solitarius, area postrema and the ventrolateral medulla. We hypothesize that those neurons are involved in mediating the physiological responses to hemorrhage.

Facilitatory role of the renin-angiotensin system in controlling adrenal catecholamine release in hemorrhaged dogs

Effects of the renin-angiotension system (RAS) on adrenal catecholamine release in response to hemorrhagic hypotension and splanchnic nerve stimulation (SNS) were studied in pentobarbital-anesthetized dogs. In hemorrhage experiments, mean blood pressure (MBP) was maintained at 50 mm Hg for 60 min by bleeding the arterial blood into a pressurized bottle. In the renal intact group (control), epinephrine (EPI) and norepinephrine (NE) output from the adrenal gland increased markedly during hemorrhagic hypotension: from 45 +/- 13 and 4.7 +/- 0.9 to 1,167 +/- 202 and 169 +/- 30 ng/min at 60 min after onset of hemorrhage, respectively. The increases in catecholamine output during hemorrhagic hypotension in the renal-intact group pretreated with captopril (1 mg/kg intravenously, i.v.) and in the renal-ligated group were significantly smaller than those in the control group. The increases in catecholamine output in the renal-ligated group infused with angiotensin II (AngII 10 ng/kg/min i.v.) were comparable to those in the control group. In SNS experiments, AngII infusion (10 ng/kg/min i.v.) enhanced increases in catecholamine output induced by 3 Hz SNS significantly. Captopril (1 mg/kg i.v.) did not affect the SNS-induced increases in catecholamine output. These results suggest that the renal RAS facilitates reflex release of adrenal catecholamines during hemorrhagic hypotension, at least in part, by acting directly on the release process of catecholamines from dog adrenal gland.

Central nervous system catecholamine content and norepinephrine release after AV3V ablation

Electrolytic ablation of the periventricular tissue surrounding the anteroventral third cerebral ventricle (AV3V-X) results in immediate increases in norepinephrine release in the paraventricular hypothalamic nucleus/anterior hypothalamus (P/A) and in the dorsomedial medulla (DM) and depletion of norepinephrine and epinephrine throughout the brain. The present study determined whether catecholamine depletion and/or altered norepinephrine release persisted after recovery from the acute effects of AV3V-X. Fourteen to eighteen days after surgery, catecholamine concentrations throughout the brain and norepinephrine release in the P/A and DM during hemorrhage were measured in control-operated and AV3V-X rats. AV3V-X decreased epinephrine content only in the midbrain, increased norepinephrine only in the cortex, and produced no differences in central nervous system dopamine. Hemorrhage-induced norepinephrine release was significantly greater in the P/A of AV3V-X rats than in control animals, whereas norepinephrine release in the DM increased equally in both groups. Thus AV3V-X does not result in chronic global central nervous system catecholamine depletion and enhances norepinephrine release in the P/A during hemorrhage.

Hepatic dysoxia commences during O2 supply dependence

Hepatic O2 consumption (VO2) remains relatively constant (O2 supply independent) as O2 delivery (DO2) progressively decreases, until a critical DO2 (DO2c) is reached below which hepatic VO2 also decreases (O2 supply dependence). Whether this decrease in VO2 represents an adaptive reduction in O2 demand or a manifestation of tissue dysoxia, i.e., O2 supply that is inadequate to support O2 demand, is unknown. We tested the hypothesis that the decrease in hepatic VO2 during O2 supply dependence represents dysoxia by evaluating hepatic mitochondrial NAD redox state during O2 supply independence and dependence induced by progressive hemorrhage in six pentobarbital-anesthetized dogs. Hepatic mitochondrial NAD redox state was estimated by measuring hepatic venous beta-hydroxybutyrate-to-acetoacetate ratio (beta OHB/AcAc). The value of DO2c was 5.02 +/- 1.64 (SD) ml.100 g-1.min-1. The beta-hydroxybutyrate-to-acetoacetate ratio was constant until a DO2 value (3.03 +/- 1.08 ml.100 g-1.min-1) was reached (P = 0.05 vs. DO2c) and then increased linearly. Peak liver lactate extraction ratio was 15.2 +/- 14.1%, occurring at a DO2 of 5.48 +/- 2.54 ml.100 g-1.min-1 (P = NS vs. DO2c). Our data support the hypothesis that the decrease in VO2 during O2 supply dependence represents tissue dysoxia.

[Histophotometric characteristics of structural-metabolic heterogeneity of hepatocytes in acute hemorrhage and pulmonary artery thromboembolism]

Basing on the data obtained at early autopsies, we compared the structure and metabolism of liver acini in acute blood loss and pulmonary artery thromboembolism. Morpho- and pathogenetic impairment of hepatocytes of various acinic zones was correlated and studied histo-enzymatically.

[The effect of dibunol on lipid peroxidation and the alpha-tocopherol level in the lungs of rats with acute blood loss]

Experiments on linear male rats were made to study the pathophysiological mechanism of the synthetic antioxidant dibunol on the levels of primary and end products of lipid peroxidation (LPO) and of alpha-tocopherol (TP) in the lungs in acute hemorrhage. Dibunol in a dose of 120 mg/kg injected 5 min after the hemorrhage inhibited LPO to the level in intact animals and raised the content of TP to the level seen in operated animals without any hemorrhage. The conclusion is drawn about a possibility of using dibunol for correction of disturbed pulmonary metabolism in urgent conditions associated with blood loss.