Pregnancy and steroid hormones enhance the systemic and regional hemodynamic effects of calcitonin gene-related peptide in rats

Calcitonin gene-related peptide (CGRP) is a potent vasodilator neuropeptide known to be involved in the regulation of vascular resistance. Several lines of evidence suggest that CGRP plays a role in the vascular adaptations that occur during normal pregnancy; however, the effects of exogenous CGRP on systemic and regional hemodynamics during pregnancy remain unknown. Therefore, the purpose of this study was to determine the hemodynamic effects of systemically administered CGRP in adult pregnant (Day 19) and ovariectomized (ovx) rats using the radioactive microsphere technique. In addition, we also used ovariectomized rats treated for 3 days with estradiol (E2), progesterone (P4), E2 + P4 in sesame oil, or oil only to assess if these hormones regulate the CGRP-induced hemodynamic changes. On the day of study, catheters were inserted into the left cardiac ventricle (through the right carotid artery), right jugular vein, and caudal tail artery. Hemodynamic studies using radioactive microspheres were then performed in conscious rats 3 h after recovery from anesthesia. Blood pressure and heart rate were continuously monitored, and left ventricular pressure was determined immediately prior to each microsphere injection. Microspheres labeled with either (141)Ce or (85)Sr were injected prior to and 2 min following the i.v. bolus injection of CGRP (270 pmol/kg body weight [BW]). Mean arterial pressure (MAP) and total vascular resistance in pregnant rats was lower than in ovx rats, and this was further decreased with an i.v. bolus injection of 270 pmol CGRP/kg BW. Cardiac output was elevated with further increases upon CGRP administration in pregnant but not in ovx rats. The CGRP-induced changes in MAP, total vascular resistance, and cardiac output in E2 + P4 -treated rats were similar to that observed in Day 19 pregnant rats, indicating that CGRP effects on these parameters during pregnancy may be modulated by steroid hormones. Both pregnancy and E2 + P4 treatment in ovx rats caused significant decreases in CGRP-induced resistance in mesenteric, coronary, and renal vasculature. Thus, the vasodilatory sensitivity to CGRP during pregnancy may be mediated through decreased total vascular resistance, particularly to coronary, mesenteric, and renal vascular beds. Thus, CGRP-induced vasodilatory effects may play a role in mediating vascular adaptations that occur during pregnancy and that steroid hormones may modulate these CGRP effects.     

Effects of naloxone on systemic and regional hemodynamic responses to exercise in dogs

To determine whether endogenous opiates have a role in circulatory regulation during mild to moderate exercise, 11 chronically instrumented dogs were exercised on a treadmill up a 6% incline at 2.5 and 5.0 mph, each for 20 min, after treatment with either the opiate receptor antagonist naloxone (1 mg/kg bolus and 20 micrograms.kg-1.min-1 infusion) or normal saline. Naloxone increased plasma beta-endorphin and adrenocorticotropic hormone at rest but had no effect on resting heart rate, aortic pressure, cardiac output, left ventricular time derivative of pressure (dP/dt) and ratio of dP/dt at a developed pressure of 50 mmHg and the developed pressure (dP/dt/P), or plasma catecholamines. Plasma beta-endorphin and adrenocorticotropic hormone increased during exercise. In addition, graded treadmill exercise produced proportional increases in heart rate, cardiac output, aortic pressure, left ventricular dP/dt and dP/dt/P, and blood flow to exercising muscles, right and left ventricular myocardium, and adrenal glands. However, there were no differences in the circulatory responses to exercise between animals receiving naloxone and normal saline. Thus the endogenous opiate system probably does not play an important role in regulating the systemic hemodynamic and blood flow responses to mild and moderate exercise.     

Role of glucagon in the splanchnic and systemic hemodynamic changes induced by portal-systemic blood shunting

Portal-systemic blood shunting is often accompanied by hyperglucagonemia and hemodynamic changes. To determine this causal relation, splanchnic and systemic hemodynamics (radioactive microspheres) and plasma glucagon levels (radioimmunoassay) were assessed in conditions of total portal-systemic shunting in portacaval-shunted (PCS) rats and in sham-operated (SO) normal rats. To compare these results, another hemodynamic study was undertaken basally and during glucagon infusion in nonoperated normal rats. PCS rats showed a threefold greater plasma glucagon concentration than SO animals (924 +/- 134 vs. 309 +/- 18 pg/ml, p less than 0.01), and they developed a hyperdynamic splanchnic circulation with higher portal venous inflow than SO rats (8.29 +/- 1.1 vs. 5.09 +/- 0.4 ml/min/100 g, p less than 0.05). Infusion of a pharmacological dose of glucagon in normal rats increased portal venous inflow (from 4.92 +/- 0.33 to 6.24 +/- 0.48 ml/min/100 g, p less than 0.05) so as to imply this hormone in the development of the hyperdynamic splanchnic circulation in conditions of portal-systemic shunting. However, the discrepancies in systemic hemodynamics between PCS and glucagon-infused rats may be a result of the different plasma glucagon levels reached in the two groups.     

Modulation of the oxidative stress and inflammatory cytokine response by thymoquinone in the collagen induced arthritis in Wistar rats

Thymoquinone (TQ) is the major active compound derived from Nigella sativa. Our aim of this work was to evaluate the antioxidant and antiarthritic activity of TQ in Wistar rat by collagen induced arthritis (CIA). TQ was administered at a dose of 5mgkg(-1) body weight once daily for 21days. The effects of treatment in the rats were assessed by biochemical (articular elastase, MPO, LPO, GSH, catalase, SOD and NO), inflammatory mediators (IL-1β, IL-6, TNF-α, IL-10, IFN-γ and PGE(2)) and histological studies in joints. TQ was effective in bringing significant changes on all the parameters (articular elastase, MPO, LPO, GSH, catalase, SOD and NO) studied. Oral administration of TQ resulted in significantly reduced the levels of pro-inflammatory mediators (IL-1β, IL-6, TNF-α, IFN-γ and PGE(2)) and increased level of IL-10. The protective effects of TQ against RA were also evident from the decrease in arthritis scoring and bone histology. In conclusion, the fact that TQ abolished a number of factors known to be involved in RA pathogenesis indicates that the administration of thymoquinone may have potential value in the treatment of inflammatory disease.     

Systemic hemodynamic and regional blood flow changes in response to chronic reductions in uterine perfusion pressure in pregnant rats

Preeclampsia (PE) is associated with increased total peripheral resistance (TPR), reduced cardiac output (CO), and diminished uterine and placental blood flow. We have developed an animal model that employs chronic reductions in uterine perfusion pressure (RUPP) in pregnant rats to generate a "preeclamptic-like" state during late gestation that is characterized by hypertension, proteinuria, and endothelial dysfunction. Although this animal model has many characteristics of human PE, the systemic hemodynamic and regional changes in blood flow that occur in response to chronic RUPP remains unknown. Therefore, we hypothesized that RUPP would decrease uteroplacental blood flow and CO, and increase TPR. Mean arterial pressure (MAP), CO, cardiac index (CI), TPR, and regional blood flow to various tissues were measured using radiolabeled microspheres in the following two groups of conscious rats: normal pregnant rats (NP; n = 8) and RUPP rats (n = 8). MAP was increased (132 +/- 4 vs. 99 +/- 3 mmHg) in the RUPP rats compared with the NP dams. The hypertension in RUPP rats was associated with increased TPR (2.15 +/- 0.02 vs. 0.98 +/- 0.08 mmHg x ml(-1) x min(-1)) and decreased CI (246 +/- 20 vs. 348 +/- 19 ml x min(-1) x kg(-1), P < 0.002) when contrasted with NP dams. Furthermore, uterine (0.16 +/- 0.03 vs. 0.38 +/- 0.09 ml x min(-1) x g tissue(-1)) and placental blood flow (0.30 +/- 0.08 vs. 0.70 +/- 0.10 ml x min(-1) x g tissue(-1)) were decreased in RUPP compared with the NP dams. These data demonstrate that the RUPP model of pregnancy-induced hypertension has systemic hemodynamic and regional blood flow alterations that are strikingly similar to those observed in women with PE.     

Evaluation and validation of virus removal by ultrafiltration during the production of diaspirin crosslinked haemoglobin (DCLHb).

Virus retention during ultrafiltration through A/G Technology filter cartridges was investigated to characterize the removal process and validate the degree of virus titre reduction during the filtration of red blood cell haemolysates performed as part of the production of diaspirin crosslinked haemoglobin (DCLHb). When viruses were suspended in phosphate buffered saline solution, retention was greater with larger sized viruses and smaller filter pore size. Virus titre was maintained at starting levels in the filter retentate circuit during the course of filtration, suggesting that the virus removal mechanism is predominantly size exclusion. Evaluation of specific processing variables indicated that the retention of phiX174 virus was increased in the presence of red blood cell haemolysate or at high membrane crossflow rates and transmembrane pressures, while the retention of EMC virus was less sensitive to variations in these parameters. Using these results to design a validation protocol, log reduction values of >7.9 were demonstrated for the retention of human immunodeficiency virus, pseudorabies virus and bovine viral diarrhoea viruses, 7.6 for hepatitis A virus, and 4.2 for porcine parvovirus. It was also shown that the retention of viruses was maintained during repetitive use of the same filter cartridge.     

Liver necrosis induced by acute intraperitoneal ethanol administration in aged rats

It is generally agreed that the deleterious pathophysiological effects of ethanol are caused, at least partially by an increase in free radical production. However, little attention has been directed to the effects of ethanol upon elderly organisms. Male Wistar rats at ages 3, 6, 12, 18 and 24 months were treated either with a single i.p. dose of 35% ethanol (v/v) at 3 g ethanol/kg body weight or an isovolumetric amount of 0.9% saline solution. We then assessed the plasma levels of transaminases and hepatic levels of oxidative stress-related parameters, followed by liver histological evaluation. The younger rats (3 months old) were not affected by the treatment with ethanol with respect to any of the studied parameters except for a lowering of total hepatic GSH and an increase in hepatic thiobarbituric acid reactants (TBARS) formation, while animals older than 3 months were increasingly more affected by the treatment. Acute ethanol treatment elicited the similar responses to those in the 3 months-old group, plus a decrease in the hepatic and plasma levels of beta-carotene and the plasma level of alpha-tocopherol, as well as an increase in the activity of plasma transaminases. In the 12,18 and 24 months old groups, there was increasing liver necrosis. These findings suggest that liver damage induced by acute ethanol administration in elderly rats may involve a lack of antioxidants.     

Splanchnic and systemic hemodynamic alterations in chronic, progressive portal hypertensive rats

Systemic and splanchnic hemodynamics were studied by using the radioactive microsphere technique, in rats in which a chronic and progressive portal or intrahepatic hypertension was produced by the placement of a nonconstricting, well fitted ligature around the portal or suprahepatic vein when the rat weighted about 100 g. The hemodynamic measurements were performed 80-90 days after ligature placement. Suprahepatic ligated rats presented portal and intrahepatic hypertension, but nonportal-systemic shunts (PSS). The only hemodynamic disturbance observed was a decrease in renal blood flow. Portal ligated rats showed a wide range of PSS and were divided in two subgroups. The subgroups with high PSS rate (greater than 10%) showed increased cardiac output and plasma renin content, as well as decreased splanchnic blood flow, portal venous inflow, hepatic blood flow and renal blood flow. Low portal-systemic shunts subgroups showed decreased cardiac output while its distribution was similar to the control rats. There was no correlation between portal pressure and shunt rate. Low shunt groups, furthermore, showed increased levels of plasma renin concentration.     

Effect of antiperoxidative drugs on gastric damage induced by ethanol in rats

Lesion formation due to oral administration of absolute ethanol could be prevented by parenteral pretreatment with antiperoxidative drugs such as butylated hydroxytoluene (BHT), quercetin and quinacrine. Also effective were allopurinol and oxypurinol, inhibitors of xanthine oxidase, but not superoxide dismutase (SOD) and hydroxyl radical scavengers, such as sodium benzoate and dimethyl sulfoxide (DMSO). BHT, quercetin, quinacrine and sulfhydryl compounds such as reduced glutathione and cysteamine which offer gastroprotection in vivo against ethanol inhibited lipid peroxidation induced in vitro by ferrous ion in porcine gastric mucosal homogenate, but SOD, sodium benzoate, DMSO, allopurinol and oxypurinol did not. These results suggest the possibility that an active species, probably derived from free iron mobilized by the xanthine oxidase system, other than oxygen radicals such as hydroxyl radicals, contributes to lipid peroxidation and lesion formation in the gastric mucosa after absolute ethanol administration.     

Modulation of restraint stress induced oxidative changes in rats by antioxidant vitamins

In the present study we examined immobilization stress-induced antioxidant defense changes in rat plasma and also observed the antioxidant effects of pre and post vitamins A, E and C administration (15 mg/Kg of body weight) individually and in combination (vit E + C) on these alterations.Following immobilization stress the circulating activities of superoxide dismutase, catalase and glutathione-S-transferase were decreased, while the level of thiobarbituric acid reactive substances (TBARS) was increased as compared to non-stressed control rats.Post treatment with individual vitamins A, E and C (after exposure to stress) resulted in a less marked alteration of plasma TBARS levels and activities of SOD, GST and catalase as compared to pre vitamin stress or stress alone treatments. Both pre and post vitamin treatments were effective in preventing stress induced derangement of free radical metabolism with a relative dominance by latter. The combined treatment with vitamin E and C did not show any additive antioxidant effect on restraint stress induced altered free radical metabolism, rather a predominant effect similar to vitamin E alone was observed. The prevention of oxidative stress generated in response to restraint stress by the vitamins can be summarized as: vitamin (E + C) i.e. vit E > vit C > vit A, thus combined vitamin (E + C) treatment though showed maximum preventive effect, but was similar to vitamin E treatment alone, in terms of the circulating activities of SOD, GST, catalase and TBARS levels.     

Voluntary induced alterations in regional ventilation in normal humans

We tested the hypothesis that voluntary changes of thoraco-abdominal shape can influence regional ventilation via altering regional pleural pressure swings (Ppl). Regional ventilation was measured simultaneously with regional Ppl during tidal volume breathing maneuvers in five normal subjects while they were performing one of three thoracoabdominal patterns of breathing: normal, preferential intercostal (IC), or preferential diaphragmatic (DIA). In every subject, the lower lung region's 133Xe washout rate was faster than the upper region's, regardless of the pattern of thoracoabdominal breathing adopted. Although IC breathing tended to make regional ventilation more homogeneous, DIA breathing tended to augment regional ventilation inhomogenities. On the average, the Ppl values were greatest in the lower lung region, regardless of the thoracoabdominal pattern adopted; however, IC breathing reduced and DIA breathing increased regional Ppl inhomogenities. When the ratios of the Ppl (lower/upper) were plotted vs. the ratios of the regional 133Xe washout decay constants (lower/upper), a significant positive correlation was found. These data suggest that a causal relation between regional tidal Ppl and regional ventilation exist, thus supporting the concept that thoracoabdominal shape changes can influence regional ventilation.     

Pancreatic ascites hemoglobin contributes to the systemic response in acute pancreatitis

Upon hemolysis extracellular hemoglobin causes oxidative stress and cytotoxicity due to its peroxidase activity. Extracellular hemoglobin may release free hemin, which increases vascular permeability, leukocyte recruitment, and adhesion molecule expression. Pancreatitis-associated ascitic fluid is reddish and may contain extracellular hemoglobin. Our aim has been to determine the role of extracellular hemoglobin in the local and systemic inflammatory response during severe acute pancreatitis in rats. To this end we studied taurocholate-induced necrotizing pancreatitis in rats. First, extracellular hemoglobin in ascites and plasma was quantified and the hemolytic action of ascitic fluid was tested. Second, we assessed whether peritoneal lavage prevented the increase in extracellular hemoglobin in plasma during pancreatitis. Third, hemoglobin was purified from rat erythrocytes and administered intraperitoneally to assess the local and systemic effects of ascitic-associated extracellular hemoglobin during acute pancreatitis. Extracellular hemoglobin and hemin levels markedly increased in ascitic fluid and plasma during necrotizing pancreatitis. Peroxidase activity was very high in ascites. The peritoneal lavage abrogated the increase in extracellular hemoglobin in plasma. The administration of extracellular hemoglobin enhanced ascites; dramatically increased abdominal fat necrosis; upregulated tumor necrosis factor-α, interleukin-1β, and interleukin-6 gene expression; and decreased expression of interleukin-10 in abdominal adipose tissue during pancreatitis. Extracellular hemoglobin enhanced the gene expression and protein levels of vascular endothelial growth factor (VEGF) and other hypoxia-inducible factor-related genes in the lung. Extracellular hemoglobin also increased myeloperoxidase activity in the lung. In conclusion, extracellular hemoglobin contributes to the inflammatory response in severe acute pancreatitis through abdominal fat necrosis and inflammation and by increasing VEGF and leukocyte infiltration into the lung.     

Alterations in hepatic metabolism of sulfur-containing amino acids induced by ethanol in rats

Summary.  Alterations in hepatic metabolism of S-amino acids were monitored over one week in male rats treated with a single dose of ethanol (3 g/kg, ip). Methionine and S-adenosylhomocysteine concentrations were increased rapidly, but S-adenosylmethionine, cysteine, and glutathione (GSH) decreased following ethanol administration. Activities of methionine adenosyltransferase, cystathionine γ-lyase and cystathionine β-synthase were all inhibited. γ-Glutamylcysteine synthetase activity was increased from t = 8 hr, but GSH level did not return to control for 24 hr. Hepatic hypotaurine and taurine levels were elevated immediately, but reduced below control in 18 hr. Changes in serum and urinary taurine levels were consistent with results observed in liver. Cysteine dioxygenase activity was increased rapidly, but declined from t = 24 hr. The results show that a single dose of ethanol induces profound changes in hepatic S-amino acid metabolism, some of which persist for several days. Ethanol not only inhibits the cysteine synthesis but suppresses the cysteine availability further by enhancing its irreversible catabolism to taurine, which would play a significant role in the depletion of hepatic GSH. Received April 26, 2002 Accepted June 12, 2002 Published online October 14, 2002 Authors' address: Young C. Kim, Ph.D., Professor of Toxicology, College of Pharmacy, Seoul National University, San 56-1 Shinrim-Dong, Kwanak-Ku, Seoul, Korea, Fax: +82-2-872-1795, E-mail: youckim@snu.ac.kr Abbreviations: CβS, cystathionine β-synthase; CDC, cysteine sulfinate decarboxylase; CDO, cysteine dioxygenase; CγL, cystathionine γ-lyase; GCS, γ-Glutamylcysteine synthetase; GSH, glutathione; MAT, methionine adenosyltransferase; SAH, S-adenosylhomocysteine; SAM, S-adenosylmethionine.     

Systemic and regional hemodynamic effects of angiotensin-(1-7) in rats

The systemic and regional hemodynamics effects of ANG-(1-7) were examined in urethane-anesthetized rats. The blood flow distribution (kidneys, skin, mesentery, lungs, spleen, brain, muscle, and adrenals), cardiac output, and total peripheral resistance were investigated by using fluorescent microspheres. Blood pressure and heart rate were recorded from the brachial artery. ANG-(1-7) infusion (110 fmol x min(-1) x 10 min(-1) iv) significantly increased blood flow to the kidney (5.10 +/- 1.07 to 8.30 +/- 0.97 ml x min(-1) x g(-1)), mesentery (0.73 +/- 0.16 to 1.17 +/- 0.49 ml x min(-1) x g(-1)), brain (1.32 +/- 0.44 to 2.18 +/- 0.85 ml x min(-1) x g(-1)), and skin (0.07 +/- 0.02 to 0.18 +/- 0.07 ml x min(-1) x g(-1)) and the vascular conductance in these organs. ANG-(1-7) also produced a significant increase in cardiac index (30%) and a decrease in total peripheral resistance (2.90 +/- 0.55 to 2.15 +/- 0.28 mmHg x ml(-1) x min x 100 g). Blood flow to the spleen, muscle, lungs, and adrenals, as well as the blood pressure and heart rate, were not altered by the ANG-(1-7) infusion. The selective ANG-(1-7) antagonist A-779 reduced the blood flow in renal, cerebral, mesenteric, and cutaneous beds and blocked the ANG-(1-7)-induced vasodilatation in the kidney, mesentery, and skin, suggesting a significant role of endogenous ANG-(1-7) in these territories. The effects of ANG-(1-7) on the cerebral blood flow, cardiac index, systolic volume, and total peripheral resistance were partially attenuated by A-779. A high dose of ANG-(1-7) (11 pmol x min(-1) x 10 min(-1)) caused an opposite effect of that produced by the low dose. Our results show for the first time that ANG-(1-7) has a previously unsuspected potent effect in the blood flow distribution and systemic hemodynamics.     

Modulation of hemoglobin dynamics by an allosteric effector

Hemoglobin (Hb) is an extensively studied paradigm of proteins that alter their function in response to allosteric effectors. Models of its action have been used as prototypes for structure‐function relationships in many proteins, and models for the molecular basis of its function have been deeply studied and extensively argued. Recent reports suggest that dynamics may play an important role in its function. Relatively little is known about the slow, correlated motions of hemoglobin subunits in various structural states because experimental and computational strategies for their characterization are challenging. Allosteric effectors such as inositol hexaphosphate (IHP) bind to both deoxy‐Hb and HbCO, albeit at different sites, leading to a lowered oxygen affinity. The manner in which these effectors impact oxygen binding is unclear and may involve changes in structure, dynamics or both. Here we use neutron spin echo measurements accompanied by wide‐angle X‐ray scattering to show that binding of IHP to HbCO results in an increase in the rate of coordinated motions of Hb subunits relative to one another with little if any change in large scale structure. This increase of large‐scale dynamics seems to be coupled with a decrease in the average magnitude of higher frequency modes of individual residues. These observations indicate that enhanced dynamic motions contribute to the functional changes induced by IHP and suggest that they may be responsible for the lowered oxygen affinity triggered by these effectors.     

Hepatic origin of hyperammonemia induced by shock in normal rats.

This study was undertaken in order to see whether instability in blood ammonia levels frequently observed in the anaesthesized rat could be explained by variations in blood pressure. In normal Wistar rats, anaesthesized with sodium pentobarbital, a bleeding of 1 ml/100 g body weigth produced in a few minutes a significant decrease in blood pressure and a significant increase in arterial blood ammonia level. With the blood pressure normalization following the blood reinfusion this hyperammonemia decreased but reappeared at high levels after a second and a third bleeding. The shock produced by an occlusion of the inferior vena cava above the renal veins gave similar results. The arterial hyperammonemia induced by shock did not result from muscle or renal ammonia production but is related to impaired hepatic uptake of portal ammonia. These results indicate that in the rat the blood pressure stability is a necessary precondition in any experiment on ammonia metabolism.     

5-HT1A受体阻断剂对乙醇引起大鼠低体温和行为性体温调节反应的影响

目的：观察5-羟色胺1A （5-HT_1A）受体阻断剂p-MPPI对乙醇引起大鼠低体温和行为性体温调节反应的影响。方法：用无线遥控测温技术记录成年雄性SD大鼠体核温度和活动的变化。用无线遥测温度梯度仪监测大鼠体核温度和行为性体温调节活动,将大鼠置于15℃~40℃的温度梯度箱内,并允许动物自由选择箱内温度,观察乙醇（3 g/kg）引起低体温和行为性体温调节的反应以及5-HT_1A受体阻断剂p-MPPI （1 mg/kg）对其效应的影响。结果：①乙醇能引起大鼠快速的体温降低反应,同时动物选择较低的环境温度。②5-HT_1A受体阻断剂p-MPPI能明显阻断乙醇引起的低体温和行为性体温调节变化。结论：①乙醇能使体温调定点降低,因为乙醇引起低体温时,大鼠选择较冷环境温度区;②5-HT可能参与乙醇引起低体温与行为性体温调节活动。