Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vivo microscopy combined with systemic blood flow and pressure measurements were used to examine the hemodynamic and microcirculatory responses to hypoxia in gills of rainbow trout and to clarify if the underlying mechanisms are adrenergic, cholinergic, serotonergic, or adenosinergic. Hypoxia (P(O2) 1.07-1.33 kPa) reduced, halted, or reversed the blood flow in the distal portion of the efferent filamental artery (EFA). Simultaneously, a large overflow to the central venous system appeared, allowing a continuous flow through many of the secondary lamellae. No vasoconstriction could be observed in this portion of the filament, showing that a vasoconstriction occurred elsewhere, possibly at the EFA sphincter, because the gill resistance (R(G)) increased. These effects were mimicked by prebranchial injection of acetylcholine, a treatment that also strongly constricted the distal efferent filamental vasculature. Atropine blocked most of the hypoxia-induced hemodynamic changes, although a minor increase in R(G) remained. The latter appeared to be of a nonadrenergic noncholinergic origin, being unaffected by additional treatment with an alpha-adrenoreceptor antagonist. It was also unaffected by blockers of serotonin and adenosine-A1 receptors. Other responses seen included a cholinergic maintenance of the systemic resistance during hypoxia and an alpha-adrenoceptor-mediated posthypoxic hypertension. This study demonstrates that hypoxia evoked a cholinergic reflex vasoconstriction located at proximal parts of the efferent filamental vasculature.
 ...
PMID:Neurochemical mechanisms behind gill microcirculatory responses to hypoxia in trout: in vivo microscopy study. 912 81

Dobutamine stress echocardiography (DSE) is an established non-invasive technique for the evaluation of coronary artery disease (CAD). It has been shown to be both safe and accurate. However, its utility and safety in the elderly, in particular, elderly Asian patients has not been studied. Between September 1992 and December 1994, we performed a total of 75 consecutive DSE studies in patients over the age of 65. Of these, 50 (67%) were females. Forty-nine patients had hypertension, 26 had diabetes mellitus, 10 were smokers, 5 had a recent or previous myocardial infarction and another 4 had a history of heart failure. Indications for DSE were, inability to perform the standard treadmill exercise test (40 patients), an abnormal resting electrocardiogram (ECG) (14 patients), a prior false positive or inconclusive treadmill test, risk stratification post myocardial infarction (4 patients) or preoperative cardiac evaluation (23 patients). The test was terminated in the majority of patients following attainment of the target heart rate. Atropine stimulation was required in 61 (81%) patients. Chest pain was provoked in 11 patients. No death or myocardial infarction occurred. Minor non-cardiac symptoms occurred in another 6 patients but this did not necessitate termination of the procedure. Three patients had transient hypotension, none of which was symptomatic. Arrhythmia occurred in 23 patients but the majority were isolated atrial or ventricular premature beats (20); 1 patient had atrial fibrillation and another developed transient junctional rhythm. Only one patient developed ventricular tachycardia but this was not haemodynamically significant and terminated easily with an intravenous dose of lignocaine. A conclusive result could be obtained in 72 (96%) patients. We concluded that DSE could be performed and interpreted in the majority of elderly Asian patients studied. Despite supplemental atropine, an aggressive dosing protocol and the inclusion of patients with a myocardial scar or history of heart failure, adverse effects were rare and often did not require any specific therapy.
 ...
PMID:Dobutamine stress echocardiography in the elderly Asian patients. 920 66

Experiments were performed on unanesthetized rats (n=6) to determine the systemic hemodynamics during chemoreflex activation by intravenous KCN. Rats chronically instrumented with ultrasonic flow probes in the ascendant aorta were submitted to KCN injections (30 microg/kg) before and after sequential administration of the autonomic blockers atropine and propranolol. In the control period KCN injections produced a 60% reduction in heart rate (HR) and a 46% elevation in blood pressure (BP), while cardiac output (CO) decreased 76%, stroke volume (SV) decreased 40%, and calculated total peripheral resistance (TPR) increased 900%. Atropine administration increased resting HR, whereas no change was observed in CO or BP. Chemoreflex-induced bradycardia was markedly attenuated (26%), and the pressor response was potentiated (59%) after atropine administration. CO and TPR responses were both attenuated after atropine administration (68% and 718%, respectively). Sequential administration of propranolol decreased HR but did not change the cardiovascular responses to KCN injections compared with the responses observed after atropine administration. In conclusion, CO is greatly reduced during KCN-evoked chemoreflex. Besides the intense bradycardia, a decrease in SV contributed to this reduction. Bradycardic response was most dependent on the cardiac parasympathetic activation, and the reduction in SV was probably most dependent on the increased cardiac afterload due to the sudden increase in BP.
Hypertension 1997 Sep
PMID:Hemodynamics of chemoreflex activation in unanesthetized rats. 932 8

The present study is designed to investigate whether acetylcholine (ACh) elicits an endothelium-derived contracting factor (EDCF) and whether it contributes to decreased relaxant response induced by ACh in Dahl rats. Dahl salt-sensitive (DS) and -resistant (DR) rats were fed a 0.4% NaCl or an 8% NaCl diet for 4 weeks. High sodium intake significantly increased blood pressure in DS rats but not in DR rats. The carotid rings were suspended for isometric tension recording. ACh caused an endothelium-dependent contraction in carotid rings from hypertensive DS rats but not from normotensive Dahl rats. Atropine, indomethacin, SQ29548, or ONO-3708 (prostaglandin H(2) [PGH(2)]/thromboxane A(2) [TXA(2)] receptor antagonist) abolished ACh-induced contraction, and OKY-046 (inhibitor of TXA(2) synthetase) partially attenuated the contraction. High sodium intake significantly enhanced contraction evoked by U46619, a PGH(2)/TXA(2) receptor agonist, in both DS and DR rats. In contrast, ACh-induced relaxation was significantly depressed in the rings from hypertensive DS rats, and ONO-3708 partially improved the depressed relaxation. Administration of ONO-8809 (an orally active PGH(2)/TXA(2) receptor antagonist; 30 micrograms per body per day) for 4 weeks neither reduced blood pressure nor improved the depressed ACh-induced relaxation in hypertensive DS rats. These results suggest that ACh causes release of EDCF in carotid rings of hypertensive DS rats, which is likely to be PGH(2) and TXA(2). The EDCF contributed in part to the depressed ACh-induced relaxation.
Hypertension 1999 Jul
PMID:Endothelium-derived contracting factor in carotid artery of hypertensive Dahl rats. 1040 21

We tested whether FR190997, a nonpeptide B(2) agonist, prevented the development of hypertension in young spontaneously hypertensive rats (SHR), which secrete less kallikrein into the urine than do Wistar-Kyoto rats. An intra-arterial (IA) injection of FR190997 (0.3 to 30 nmol/kg) caused dose-dependent hypotension in conscious Sprague-Dawley rats. Although the maximum hypotensive potency of FR190997 equaled that of bradykinin, its action lasted approximately 10 times as long. Hoe140 (100 nmol/kg IA) significantly blocked the hypotensive response induced by FR190997 (10 nmol/kg). Atropine (100 nmol/kg IA) did not affect this response. A selective infusion of FR190997 into the renal artery induced natriuresis and diuresis in anesthetized rabbits. A continuous infusion (2 nmol. 10 mL(-1). h(-1) per rat) of FR190997 into the abdominal aorta of young SHR (6 weeks old, n=6) for 6 days significantly (P<0.05) reduced mean blood pressure to 114+/-6 (day 2) and 110+/-6 (day 5) mm Hg, from 149+/-7 and 162+/-6 mm Hg, respectively, in vehicle-infused rats (n=6). At 8 days after continuous infusion (day 14), mean blood pressure (148+/-5 mm Hg) in FR190997-infused rats remained significantly (P<0. 05) lower than that in vehicle-infused rats (190+/-6 mm Hg), almost the peak value. The mesenteric artery isolated from FR190997-treated rats (day 14) had lower contractile sensitivity to norepinephrine than that from vehicle-treated rats. These results suggested that the continuous infusion of a nonpeptide B(2) agonist may prevent hypertension if performed in the critical phase.
Hypertension 2000 Jan
PMID:A nonpeptide mimic of bradykinin blunts the development of hypertension in young spontaneously hypertensive rats. 1064 38

Cardiopulmonary resuscitation (CPR) provides artificial circulation and ventilation during cardiopulmonary arrest. CPR is further categorised as basic life support (BLS), advanced cardiac life support (ACLS) and postresuscitation support. BLS consists of provision of a patent upper airway, ventilation and circulation of blood by closed chest cardiac compressions. ACLS includes use of specialised equipment to maintain the airway, early defibrillation and pharmacologic therapy. Successful outcome from an arrest depends on the total duration of an arrest and early defibrillation, as ventricular fibrillation is the most common cardiac rhythm found in adult cardiac arrest. Initial drug therapy during CPR aims at correction of arterial hypoxaemia and restoring coronary and cerebral perfusion. Oxygen and epinephrine constitute the mainstay of drug therapy during CPR. In patients with ventricular tachycardia, lidocaine is the drug of choice, followed by bretylium. Magnesium has proved to be useful in both refractory pulseless ventricular tachycardia and fibrillation. Atropine has not been demonstrated to improve outcome from arrest but can be administered in bradyasystolic cardiac arrest. The routine administration of bicarbonate and calcium is no longer recommended but situations exist where they can be used appropriately. Administration of drugs during CPR should preferably be via a central route, but epinephrine, lidocaine and atropine can be administered via the endotracheal tube if intravenous access has not been established. Postresuscitation care includes mechanical ventilation if necessary to optimise oxygenation and ventilation and steps to maintain vital organ and optimal brain protection, which includes avoidance of hypertension, hypotension and hyperglycaemia.
 ...
PMID:Current concepts in cardiopulmonary resuscitation in adults. 1064 88

Many toxins from scorpion venoms activate sodium channels, thereby enhancing neurotransmitter release. The aim of the present work was to determine if the in vivo and in vitro effects of Leiurus quinquestriatus venom (LQQ) could be ameliorated by lignocaine, a sodium channel blocker. In urethane anaesthetised rabbits, LQQ venom (0.5 mg kg(-1), i.v.) caused initial hypotension and bradycardia followed by hypertension, pulmonary oedema, electrocardiographic changes indicating conduction defects, ischaemia, infarction, and then hypotension and death. Lignocaine (1 mg kg(-1) i.v. bolus initially, followed by i.v. infusion of 50 microg kg(-1) min(-1)) significantly attenuated the majority of the venom-evoked effects and reduced mortality. Addition of LQQ venom (1, 3 and 10 microg ml(-1)) to chick biventer cervicis, guinea pig ileum, and rat vas deferens preparations, increased the height of electrically-induced twitches, elevated resting tension, and caused autorhythmic oscillations. Lignocaine (3 x 10(-4)-1.2 x 10(-3) M) greatly attenuated these venom-evoked actions in the three preparations. Antagonists of appropriate neurotransmitters were also tested to determine the contribution of released transmitters to LQQ effects. Atropine significantly decreased the venom-elicited effects on guinea pig ileum preparations, while prazosin and guanethidine significantly reduced the venom's actions on rat vas deferens. In chick biventer cervicis preparations, tubocurarine and hexamethonium significantly attenuated the venom-induced effects. This study supports the hypothesis that many effects of LQQ venom involve the release of neurotransmitters and may be ameliorated by treatment with lignocaine.
 ...
PMID:The effects of lignocaine on actions of the venom from the yellow scorpion "Leiurus quinquestriatus" in vivo and in vitro. 1085 17

The present study examined if changes in cardiac after-load would affect QT interval dispersion. QT dispersion (QTd) on the 12-lead electrocardiogram is believed to be a noninvasive measure of electrical inhomogeneity in the heart and has recently been identified as a sensitive predictor of sudden cardiac death. In experimental models, an increase in cardiac afterload has been shown to alter action potential durations through mechanoelectrical feedback. This may result in an altered dispersion of action potential repolarization in the ventricle. Until now, there has been little evidence for this occurring in man in vivo. In the present study, the effects of afterload on QTd were examined in 10 healthy male volunteers (mean age [SD] 25 years [4.5]) who received an intravenous infusion of phenylephrine (0.2 to 3.6 microg/kg/min) given in incremental doses, and placebo in a blinded, crossover fashion. Because phenylephrine is known to alter heart rate (HR) significantly (via a reflex vagal response), the study was performed with and without atropine. We found a significant positive correlation between acute changes in blood pressure (BP) and changes in all QTd indexes (deltaQTd/delta systolic BP and deltaQTcd/deltasystolic BP r values 0.67 and 0.60, respectively; p <0.001). This relation was independent of HR changes or reflex vagal activity. Atropine had no significant effect on QTd. These observations have important clinical implications and may partly account for why sudden deaths and arrhythmic complications occur so frequently in conditions associated with increased after-load, such as hypertension and heart failure.
 ...
PMID:Effect of phenylephrine with and without atropine on QT dispersion in healthy normotensive men. 1107 40

Dobutamine stress echocardiography (DSE) and exercise stress echocardiography (ESE) are widely used for diagnosis of coronary artery disease. Each of these methods has limitations: secondary effects of Dobutamine, poor imaging quality, difficulty in attaining the maximal heart rate. The authors evaluated a test associating pedalling exercise at a constant low load (30-60 watts) with Dobutamine infusion (10-20-30-40 j/Kg/min +/- Atropine) (DES + E) in 42 patients referred for suspected coronary artery disease. All patients underwent coronary angiography on Day 1. There was significant coronary disease (> 50% stenosis) in 19 of the 42 patients. Sensitivity, specificity, negative predictive value, positive predictive value and overall diagnosis value were respectively 84, 87, 84, 87 and 86%. In the first 20 patients, the DES + E was compared directly with DES: There was only one undesirable side effect (hypertension) with DES + E compared with 5 with DES alone. The target heart rate was attained with lower doses of Dobutamine with DES + E (32.35 vs 39.42 j/Kg/min, p = 0.05). DES + E therefore seems to be a promising technique which is better tolerated than DES alone with very satisfactory diagnostic performances. However, these results require further confirmation in larger numbers of patients.
 ...
PMID:[Evaluation of a new stress echocardiography technique combining exercise and dobutamine in the detection of coronary disease]. 1133 54

Nineteen patients with major depression were alternately given intravenous atropine or saline immediately prior to anesthesia for electroconvulsive therapy (ECT). Atropine increased the heart rate, reduced the number of dropped beats, and reduced the number of premature atrial beats. These features may be advantageous in patients with cardiac hypodynamic states presenting for ECT, that is, with bradycardia, bradyarrhythmia, or hypotension. However, as atropine also increased the cardiac work, we recommend that it not be given to patients with hypertension, tachycardia, or who are at risk for cardiac ischemia.
 ...
PMID:Atropine in Electroconvulsive Therapy. 1194 Sep 94


<< Previous 1 2 3 4 5 6 Next >>