Reversal of acute coagulopathy during hypotensive resuscitation using small-volume 7.5% NaCl adenocaine and Mg2+ in the rat model of severe hemorrhagic shock

OBJECTIVE: : Acute traumatic coagulopathy occurs early in hemorrhagic trauma and is a major contributor to mortality and morbidity. Our aim was to examine the effect of small-volume 7.5% NaCl adenocaine (adenosine and lidocaine, adenocaine) and Mg on hypotensive resuscitation and coagulopathy in the rat model of severe hemorrhagic shock. DESIGN: : Prospective randomized laboratory investigation. SUBJECTS: : A total of 68 male Sprague Dawley Rats. INTERVENTION: : Post-hemorrhagic shock treatment for acute traumatic coagulopathy. MEASUREMENTS AND METHODS: : Nonheparinized male Sprague-Dawley rats (300-450 g, n = 68) were randomly assigned to either: 1) untreated; 2) 7.5% NaCl; 3) 7.5% NaCl adenocaine; 4) 7.5% NaCl Mg; or 5) 7.5% NaCl adenocaine/Mg. Hemorrhagic shock was induced by phlebotomy to mean arterial pressure of 35-40 mm Hg for 20 mins (~40% blood loss), and animals were left in shock for 60 mins. Bolus (0.3 mL) was injected into the femoral vein and hemodynamics monitored. Blood was collected in Na citrate (3.2%) tubes, centrifuged, and the plasma snap frozen in liquid N2 and stored at -80°C. Coagulation was assessed using activated partial thromboplastin times and prothrombin times. RESULTS: : Small-volume 7.5% NaCl adenocaine and 7.5% NaCl adenocaine/Mg were the only two groups that gradually increased mean arterial pressure 1.6-fold from 38-39 mm Hg to 52 and 64 mm Hg, respectively, at 60 mins (p < .05). Baseline plasma activated partial thromboplastin time was 17 ± 0.5 secs and increased to 63 ± 21 secs after bleeding time, and 217 ± 32 secs after 60-min shock. At 60-min resuscitation, activated partial thromboplastin time values for untreated, 7.5% NaCl, 7.5% NaCl/Mg, and 7.5% NaCl adenocaine rats were 269 ± 31 secs, 262 ± 38 secs, 150 ± 43 secs, and 244 ± 38 secs, respectively. In contrast, activated partial thromboplastin time for 7.5% NaCl adenocaine/Mg was 24 ± 2 secs (p < .05). Baseline prothrombin time was 28 ± 0.8 secs (n = 8) and followed a similar pattern of correction. CONCLUSIONS: : Plasma activated partial thromboplastin time and prothrombin time increased over 10-fold during the bleed and shock periods prior to resuscitation, and a small-volume (~1 mL/kg) IV bolus of 7.5% NaCl AL/Mg was the only treatment group that raised mean arterial pressure into the permissive range and returned activated partial thromboplastin time and prothrombin time clotting times to baseline at 60 mins.

Anti-hypotensive treatment and endothelin blockade synergistically antagonize exercise fatigue in rats under simulated high altitude.

Rapid ascent to high altitude causes illness and fatigue, and there is a demand for effective acute treatments to alleviate such effects. We hypothesized that increased oxygen delivery to the tissue using a combination of a hypertensive agent and an endothelin receptor A antagonist drugs would limit exercise-induced fatigue at simulated high altitude. Our data showed that the combination of 0.1 mg/kg ambrisentan with either 20 mg/kg ephedrine or 10 mg/kg methylphenidate significantly improved exercise duration in rats at simulated altitude of 4,267 m, whereas the individual compounds did not. In normoxic, anesthetized rats, ephedrine alone and in combination with ambrisentan increased heart rate, peripheral blood flow, carotid and pulmonary arterial pressures, breathing rate, and vastus lateralis muscle oxygenation, but under inspired hypoxia, only the combination treatment significantly enhanced muscle oxygenation. Our results suggest that sympathomimetic agents combined with endothelin-A receptor blockers offset altitude-induced fatigue in rats by synergistically increasing the delivery rate of oxygen to hypoxic muscle by concomitantly augmenting perfusion pressure and improving capillary conductance in the skeletal muscle. Our findings might therefore serve as a basis to develop an effective treatment to prevent high-altitude illness and fatigue in humans.

Stroma-free hemoglobin increases blood pressure and GFR in the hypotensive rat: role of nitric oxide.

The short-term systemic and renal hemodynamic effects of two stroma-free hemoglobin (SFH) solutions, one unmodified and the other modified by cross-linking, were examined in anesthetized rats after hemorrhagic hypotension. Both forms of SFH increased mean arterial pressure (MAP) and glomerular filtration rate (GFR) to baseline (prehemorrhage) values. The increase in MAP induced by unmodified SFH was greater than the increase in MAP caused by an albumin solution isoncotic to the unmodified SFH solution. Similarly, the increase in MAP caused by the modified SFH was also substantially greater than that induced by an albumin solution of comparable oncotic pressure to the modified SFH solution. Both unmodified and modified SFH increased GFR. As with MAP, the increase in GFR induced by both SFH solutions was greater than that associated with the oncotically matched albumin solutions. In separate experiments, the effects of nitric oxide (NO) inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) on MAP after hemorrhagic hypotension and subsequent infusion of unmodified SFH or albumin were also examined. In the albumin-infused rats, L-NAME increased MAP. In marked contrast, NO inhibition with L-NAME had no further effect on MAP when infused after SFH. We conclude that both unmodified and modified SFH solutions acutely improve MAP and GFR by the combined effects of intravascular volume expansion resulting from the colloid effect of the protein and by inactivation of NO.

Protocol-driven adjustment of ocular hypotensive medication in patients at low risk of conversion to glaucoma

AIM: To investigate the safety and potential savings of decreasing medication use in low-risk patients with ocular hypertension (OH).
METHODS: Patients with OH receiving pressure-lowering medication identified by medical record review at a university hospital underwent examination by a glaucoma specialist with assessment of visual field (VF), vertical cup-to-disc ratio (vCDR), central corneal thickness and intraocular pressure (IOP). Subjects with estimated 5-year risk of glaucoma conversion <15% were asked to discontinue ≥1 medication, IOP was remeasured 1 month later and risk was re-evaluated at 1 year.
RESULTS: Among 212 eyes of 126 patients, 44 (20.8%) had 5-year risk >15% and 14 (6.6%) had unreliable baseline VF. At 1 month, 15 patients (29 eyes, 13.7%) defaulted follow-up or refused to discontinue medication and 11 eyes (5.2%) had risk >15%. The remaining 69 patients (107 eyes, 50.7%) successfully discontinued 141 medications and completed 1-year follow-up. Mean IOP (20.5±2.65 mm Hg vs 20.3±3.40, p=0.397) did not change, though mean VF pattern SD (1.58±0.41 dB vs 1.75±0.56 dB, p=0.001) and glaucoma conversion risk (7.31±3.74% vs 8.76±6.28%, p=0.001) increased at 1 year. Mean defect decreased (-1.42±1.60 vs -1.07±1.52, p=0.022). One eye (0.47%) developed a repeatable VF defect and 13 eyes (6.1%) had 5-year risk >15% at 1 year. The total 1-year cost of medications saved was US$4596.
CONCLUSIONS: Nearly half (43.9%) of low-risk OH eyes in this setting could safely reduce medications over 1 year, realising substantial savings.Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

The hypotensive effect of exercise on IOP : an interaction of physical fitness and parasympathetic efficacy

RÉSUMÉ Suite à une centaine de publications sur la réduction de la PIO post-exercice, il est connu que parmi un grand nombre de programme d'exercices de différentes durées et intensités, les effets hypotenseurs de l'exercice sur la PIO sont atténués chez les sujets en bonne condition physique. Le mécanisme proposé est l'augmentation potentielle de l'efficacité du système parasympathique avec l'activité physique. Le principal objectif de cette thèse est d'identifier les facteurs contribuants à la réduction de la PIO post-exercice et d'élucider les différents mécanismes possibles. L'étude 1, une méta-analyse, a été menée afin de quantifier les contributions relatives de l'intensité et de la durée de l'effet de l'exercice sur la PIO et la mesure dans laquelle ces variables affectent les sujets sédentaires et normalement actifs. La tendance ressortant des résultats est que la diminution de la PIO suite à de l'exercice aérobie est plus élevée chez les sujets sédentaires que les sujets en bonne condition physique. (ES = -4.198 mm Hg et -2.340 mm Hg, respectivement). L'absence d'un contrôle des liquides ingérés avant l'activité physique est à souligné dans cette étude. L'hyperosmolarité (un effet secondaire de la déshydratation) est l'un des mécanismes proposés influant l'effet hypotenseur de l'exercice. L'étude 2 comparait la réduction de la PIO dans deux conditions, soit hypohydraté et hyperhydraté, avant, pendant et après un effort de 90 minutes sur un ergocycle. Après une diminution initiale pour les deux conditions, la PIO revient aux valeurs de départ pour la condition hypohydratée malgré une perte de poids significative et elle augmente pour la condition hyperhydratée (résultat du protocole d'hydratation). Étant donné le niveau élevé de participants en bonne condition physique dans l'étude 2, la troisième étude a été conçue afin de etude la relation entre la PIO et la condition physique. À l'aide d'analyses corrélationnelles il a été possible d'observer la relation entre le test de vo2max et la moyenne des mesures de PIO prises sur un intervalle de huit semaines. Une relation significative n'existait que pour les participants se situant dans la portion supérieure du continuum de la condition physique. Conclusion: Les résultats de la présente étude suggèrent que l'effet hypotenseur de l'exercice sur la PIO est probablement une réponse homéostatique à la dérégulation de l'humeur aqueuse causée par l'initiation de l'exercice et le protocole d'ingestion de fluides pré-exercice.

Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial

Background Hawthorn (Crataegus laevigata) leaves, flowers and berries are used by herbal practitioners in the UK to treat hypertension in conjunction with prescribed drugs. Small-scale human studies support this approach. Aim To investigate the effects of hawthorn for hypertension in patients with type 2 diabetes taking prescribed drugs. Design of study Randomised controlled trial. Setting General practices in Reading, UK. Method Patients with type 2 diabetes (n = 79) were randomised to daily 1200 mg hawthorn extract (n = 39) or placebo (n = 40) for 16 weeks. At baseline and outcome a wellbeing questionnaire was completed and blood pressure and fasting blood samples taken. A food frequency questionnaire estimated nutrient intake. Results Hypotensive drugs were used by 71% of the study population with a mean intake of 4.4 hypoglycaemic and/or hypotensive drugs. Fat intake was lower and sugar intake higher than recommendations, and low micronutrient intake was prevalent. There was a significant group difference in mean diastolic blood pressure reductions (P = 0.035): the hawthorn group showed greater reductions (baseline: 85.6 mmHg, 95% confidence interval [Cl] = 83.3 to 87.8; outcome: 83.0 mmHg, 95% Cl = 80.5 to 85.7) than the placebo group (baseline: 84.5 mmHg, 95% Cl = 82 to 87; outcome: 85.0 mmHg, 95% Cl = 82.2 to 87.8). There was no group difference in systolic blood pressure reduction from baseline (3.6 and 0.8 mmHg for hawthorn and placebo groups, respectively; P = 0.329). Although mean fat intake met current recommendations, mean sugar intake was higher and there were indications of potential multiple micronutrient deficiencies. No herb-drug interaction was found and minor health complaints were reduced from baseline in both groups. Conclusions This is the first randomised controlled trial to demonstrate a hypotensive effect of hawthorn in patients with diabetes taking medication.

Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial

Background: Hawthorn (Crataegus laevigata) leaves, flowers and berries are used by herbal practitioners in the UK to treat hypertension in conjunction with prescribed drugs. Small-scale human studies support this approach. Aim: To investigate the effects of hawthorn for hypertension in patients with type 2 diabetes taking prescribed drugs. Design of study: Randomised controlled trial. Setting: General practices in Reading, UK. Method: Patients with type 2 diabetes (n = 79) were randomised to daily 1200 mg hawthorn extract (n = 39) or placebo (n = 40) for 16 weeks. At baseline and outcome a wellbeing questionnaire was completed and blood pressure and fasting blood samples taken. A food frequency questionnaire estimated nutrient intake. Results: Hypotensive drugs were used by 71% of the study population with a mean intake of 4.4 hypoglycaemic and/or hypotensive drugs. Fat intake was lower and sugar intake higher than recommendations, and low micronutrient intake was prevalent. There was a significant group difference in mean diastolic blood pressure reductions (P = 0.035): the hawthorn group showed greater reductions (baseline: 85.6 mmHg, 95% confidence interval [Cl] = 83.3 to 87.8; outcome: 83.0 mmHg, 95% Cl = 80.5 to 85.7) than the placebo group (baseline: 84.5 mmHg, 95% Cl = 82 to 87; outcome: 85.0 mmHg, 95% Cl = 82.2 to 87.8). There was no group difference in systolic blood pressure reduction from baseline (3.6 and 0.8 mmHg for hawthorn and placebo groups, respectively; P = 0.329). Although mean fat intake met current recommendations, mean sugar intake was higher and there were indications of potential multiple micronutrient deficiencies. No herb-drug interaction was found and minor health complaints were reduced from baseline in both groups. Conclusions: This is the first randomised controlled trial to demonstrate a hypotensive effect of hawthorn in patients with diabetes taking medication.

Hypotensive and vasorelaxing effects of the new NO-donor [Ru(terpy)(bdq)NO+](3+) in spontaneously hypertensive rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The bradycardic and hypotensive responses to serotonin are reduced by activation of GABA A receptors in the nucleus tractus solitarius of awake rats

We investigated the effects of bilateral injections of the GABA receptor agonists muscimol (GABA A) and baclofen (GABA B) into the nucleus tractus solitarius (NTS) on the bradycardia and hypotension induced by iv serotonin injections (5-HT, 2 µg/rat) in awake male Holtzman rats. 5-HT was injected in rats with stainless steel cannulas implanted bilaterally in the NTS, before and 5, 15, and 60 min after bilateral injections of muscimol or baclofen into the NTS. The responses to 5-HT were tested before and after the injection of atropine methyl bromide. Muscimol (50 pmol/50 nl, N = 8) into the NTS increased basal mean arterial pressure (MAP) from 115 ± 4 to 144 ± 6 mmHg, did not change basal heart rate (HR) and reduced the bradycardia (-40 ± 14 and -73 ± 26 bpm at 5 and 15 min, respectively, vs -180 ± 20 bpm for the control) and hypotension (-11 ± 4 and -14 ± 4 mmHg, vs -40 ± 9 mmHg for the control) elicited by 5-HT. Baclofen (12.5 pmol/50 nl, N = 7) into the NTS also increased basal MAP, but did not change basal HR, bradycardia or hypotension in response to 5-HT injections. Atropine methyl bromide (1 mg/kg body weight) injected iv reduced the bradycardic and hypotensive responses to 5-HT injections. The stimulation of GABA A receptors in the NTS of awake rats elicits a significant increase in basal MAP and decreases the cardiac Bezold-Jarisch reflex responses to iv 5-HT injections.

Structural and functional characterization of an acidic platelet aggregation inhibitor and hypotensive phospholipase A(2) from Bothrops jararacussu snake venom

An acidic (pI similar to 4.5) phospholipase A(2) (BthA-I-PLA(2)) was isolated from Bothrops jararacussu snake venom by ion-exchange chromatography on a CM-Sepharose column followed by reverse phase chromatography on an RP-HPLC C-18 column. It is an similar to13.7 kDa single chain Asp49 PLA(2) with approximately 122 amino acid residues, 7 disulfide bridges, and the following N-terminal sequence: 'SLWQFGKMINYVMJGESGVLQYLSYGCYCGLGGQGQPTDATDRCCFVHDCC(51). Crystals of this acidic protein diffracted beyond 2.0 Angstrom resolution. These crystals are monoclinic and have unit cell dimensions of a = 33.9, b = 63.8, c = 49.1 Angstrom, and beta = 104.0degrees. Although not myotoxic, cytotoxic, or lethal, the protein was catalytically 3-4 tithes more active than BthTX-II, a basic D49 myotoxic PLA(2) from the same venom and other Bothrops venoms. Although it showed no toxic activity, it was able to induce time-independent edema, this activity being inhibited by EDTA. In addition, BthA-I-PLA(2) caused a hypotensive response in the rat and inhibited platelet aggregation, Catalytic, antiplatelet and other activities were abolished by chemical modification with 4-bromophenacyl bromide, which is known to covalently bind to His48 of the catalytic site. Antibodies raised against crude B. jararacussu venom recognized this acidic PLA(2), while anti-Asp49-BthTX-II recognized it weakly and anti-Lys49-BthTX-I showed the least cross-reaction. These data confirm that myotoxicity does not necessarily correlate with catalytic activity in native PLA(2) homologues and that either of these two activities may exist alone. BthA-I-PLA(2), in addition to representing a relevant molecular model of catalytic activity, is also a promising hypotensive agent and platelet aggregation inhibitor for further studies. (C) 2002 Elsevier B.V. All rights reserved.

Crystal structure of an acidic platelet aggregation inhibitor and hypotensive phospholipase A(2) in the monomeric and dimeric states: insights into its oligomeric state

Phospholipases A(2) belong to the superfamily of proteins which hydrolyzes the sn-2 acyl groups of membrane phospholipids to release arachidonic acid and lysophospholipids. An acidic phospholipase A(2) isolated from Bothrops juraracussu snake venom presents a high catalytic, platelet aggregation inhibition and hypotensive activities. This protein was crystallized in two oligomeric states: monomeric and dimeric. The crystal structures were solved at 1.79 and 1.90 Angstrom resolution, respectively, for the two states. It was identified a Na+ ion at the center of Ca2+-binding site of the monomeric form. A novel dimeric conformation with the active sites exposed to the solvent was observed. Conformational states of the molecule may be due to the physicochemical conditions used in the crystallization experiments. We suggest dimeric state is one found in vivo. (C) 2004 Elsevier B.V. All rights reserved.

Crystallization and preliminary X-ray diffraction studies of BmooPLA(2)-I, a platelet-aggregation inhibitor and hypotensive phospholipase A(2) from Bothrops moojeni venom

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)