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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tolazoline, a drug used in the treatment of hypertension, has been described as a typical H2 agonist. In this study possible immunomodulating properties of tolazoline were investigated. A single injection of tolazoline 1 day before immunization caused an effect on delayed hypersensitivity that depended on the antigen dose. The response to 10(5) and 10(6) sheep red blood cells (SRBC) was decreased, whereas the response to 10(9) SRBC was enhanced. Administration of tolazoline 4 days after immunization predominantly affected the humoral response. The IgM response was inhibited in favour of the IgG response. Low doses of tolazoline, given to animals simultaneously with the elicitation for delayed hypersensitivity, lead to a more severe inflammation. The possible involvement of suppressor cells and vessels in tolazoline action is discussed. The application of tolazoline in the immunotherapy of human cancer is suggested.
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PMID:Histamine 2 receptor-mediated immunomodulation in the mouse. I. Immunomodulation by the H2 agonist tolazoline. 45 85

Persiting pulmonary arterial hypertension, whether secondary to known lung disease or apparently idiopathic, may induce refractory hypoxaemia in the newborn. Tolazoline, pulmonary vasodilator of choice here, was used to treat this syndrome in 13 newborns. Therapeutic indications, precautions and possible side-effects are discussed.
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PMID:[Refractory hypoxemia in the newborn. Treatment with tolazoline]. 54 38

Xylazole (Xyl) is an analogue of xylazine (Xyn) synthesized by Lanzhou Institute of Chinese Traditional Veterinary Medicine. The effects of Xyl on heart rate and blood pressure were studied in 5 conscious dogs. Xyl 1 mg/kg iv was similar to Xyn in producing bradycardia and an initial transient hypertension followed by a lasting hypotension which was less significant than Xyn. Yohimbine (0.1 and 0.3 mg/kg), an alpha 2-adrenoreceptor blocking agent, antagonized bradycardia and hypotension induced by Xyl. Tolazoline (3.3 mg/kg), a nonselective alpha-adrenoreceptor blocking agent, reversed the bradycardia and hypotensive effect. Prazosin (1 mg/kg), an alpha 1-adrenoreceptor blocking agent, did not change Xyl-induced bradycardia and hypotension. Atropine (20 micrograms/kg) not only antagonized Xyl-induced bradycardia but also changed from bradycardia to tachycardia, and greatly potentiated Xyl-induced hypertension for more than 30 min. The results suggested that Xyl-induced cardiovascular effects are similar to Xyn that mediated by alpha 2-adrenoreceptor.
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PMID:[Effects of xylazole on heart rate and blood pressure in conscious dogs]. 257 38

The effects of jingsongling (JSL) and xylazine on heart rate (HR) and mean arterial pressure (MAP) were studied in five conscious male dogs. An i.v. injection of xylazine (1 mg/kg) caused a bradycardia, an initial hypertension, and a subsequent hypotension. An i.v. injection of JSL (1 mg/kg) caused a bradycardia and a 20-min hypertension without a subsequent hypotension. Atropine sulfate (45 micrograms/kg, i.v.) increased HR for 30 min without changing MAP, and antagonized JSL-induced bradycardia for at least 60 min. There was a subsequent rebound bradycardia. Atropine sulfate potentiated JSL-induced hypertension in both magnitude and duration. Yohimbine (0.1 mg/kg, i.v.), an alpha 2-adrenoceptor antagonist, increased HR and MAP for 110 and 70 min, respectively. Yohimbine not only failed to potentiate but even reversed the pressor effect of JSL in a dose-dependent manner. Yohimbine also caused a dose-dependent reversal of JSL-induced bradycardia. Tolazoline (5 mg/kg, i.v.), a nonselective alpha-adrenoceptor antagonist, increased MAP for 20 min without changing HR. Tolazoline also reversed JSL-induced hypertension and bradycardia. Prazosin (1 mg/kg), an alpha 1-adrenoceptor antagonist, decreased MAP and increased HR for at least 110 min. Prazosin reversed JSL-induced hypertension but failed to affect JSL-induced bradycardia. These results indicated that: (1) JSL-induced bradycardia and hypertension are mediated by alpha 2-adrenoceptors; (2) yohimbine and tolazoline may be useful in antagonizing these untoward reactions associated with JSL administration, whereas prazosin and atropine were not found to be beneficial in this regard.
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PMID:The effects of jingsongling, a xylazine analog, on mean arterial blood pressure and heart rate in dogs--influences of yohimbine, tolazoline, prazosin, and atropine. 281 Apr 77

The effect of amitraz on heart rate (HR) and mean aortic blood pressure (MAP) were studied in five conscious male dogs. An iv injection of amitraz (1 mg/kg) caused a decrease in HR, which was accompanied by sinus arrhythmia for at least 60 min. Administration of amitraz also caused an increase in MAP for 20 min. Atropine sulfate (0.045 mg/kg, iv) increased HR and prevented amitraz-induced bradycardia. In addition, atropine potentiated amitraz-induced hypertension for 45 min. Yohimbine, an alpha 2-adrenoreceptor antagonist, given iv at 0.1 mg/kg, prevented hypertension, bradycardia, and sinus arrhythmia induced by amitraz. Tolazoline, a nonselective alpha-adrenoreceptor antagonist, given iv at 5 mg/kg, reduced the bradycardia and sinus arrhythmia caused by amitraz administration but did not change amitraz-induced hypertension. Tolazoline alone also increased both HR and MAP. Prazosin, an alpha 1-adrenoreceptor antagonist, given iv at 1 mg/kg, did not affect the cardiovascular actions of amitraz. The results suggest that (1) alpha 2-adrenoreceptors mediate amitraz-induced bradycardia and hypertension, and (2) yohimbine, but not atropine, can be used to control the untoward reactions of amitraz.
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PMID:Effect of amitraz on heart rate and aortic blood pressure in conscious dogs: influence of atropine, prazosin, tolazoline, and yohimbine. 301 23

Fourteen wolves (Canis lupus L.) were singularly or repeatedly immobilized with 30 mg xylazine hydrochloride (HCl) and 400 mg ketamine HCl. Mean induction time was 5.3 +/- 4.6 min (mean +/- SD). Administration of 8.0 mg/kg tolazoline HCl as an antagonist significantly reduced immobilization times from 148.0 +/- 52.7 to 47.9 +/- 8.9 min (F = 63.69, df = 1,17, P less than 0.05). The average times from injection to ambulation for 2.0, 4.0, and 8.0 mg/kg tolazoline HCl were 35.2 +/- 31.8, 18.5 +/- 11.7, and 10.2 +/- 9.1 min. Tolazoline HCl increased heart rates significantly (P less than 0.001) from 75 +/- 14 to 120 +/- 23 beats/min, reversing a xylazine HCl-induced bradycardia. Respiratory rates also increased significantly (P less than 0.01) after tolazoline HCl injection from 19 +/- 7 to 28 +/- 8 breaths/min. Immobilization resulted in an initial hypertension which was normalized after tolazoline HCl administration. One female wolf had a single sinoatrial block within 1 min of receiving tolazoline HCl. Tolazoline HCl appears to be an effective antagonist for xylazine HCl-ketamine HCl immobilization of wolves.
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PMID:Xylazine hydrochloride-ketamine hydrochloride immobilization of wolves and its antagonism by tolazoline hydrochloride. 373 86

The cardiovascular actions of tolazoline are poorly understood. Therefore, we administered tolazoline (2 mg kg-1, IV) to anesthetized adult dogs and puppies. Tolazoline induced transient pulmonary and systemic pressor responses, transient systemic vasoconstriction and pulmonary vasodilation, and transient hypoxemia and acidosis in pentobarbital anesthetized dogs. None of these responses were evident during a second injection of tolazoline, indicating either the development of tachyphylaxis or a secondary antagonistic property of tolazoline. These responses to tolazoline were also prevented by alpha adrenergic blockade. Histamine H1 - and H2-receptor blockade sustained the transient pulmonary and systemic pressor and systemic vasoconstrictor responses to tolazoline. Thus, tolazoline appears to activate both alpha and histamine receptors in the pulmonary and systemic vascular beds of the anesthetized dog. In anesthetized puppies, tolazoline induced a slight pulmonary pressor response, marked bradycardia, and systemic hypertension. The present findings confirm the pharmacological complexity of tolazoline and suggest that anesthesia, age, and pulmonary vascular tone are important factors in determining the cardiovascular responses to tolazoline.
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PMID:Pulmonary and systemic vascular actions of tolazoline in anesthetized dogs. 629 95

Trauma due to motor vehicles accident and urban violence have made distal arterial reconstruction an increasingly important part of the surgeon's work. During the 20 month period from October 1980 to May 1982, 13 patients with below the knee and 2 patients with forearm trauma had nonviable extremities despite fastidious vascular and orthopedic reconstruction. A continuous intraarterial infusion of tolazoline into the femoral or brachial arteries restored vascular perfusion and viability in 13 of 15 patients (87 percent), with eventual limb salvage in 67 percent. Seven of 15 patients (47 percent) had transient systemic hypertension. There was no mortality. There exists in patients with these catastrophic injuries a local low-flow state due to a combination of distal arterial spasm and venous outflow obstruction. Tolazoline, a peripheral alpha-adrenergic blocking agent, increases blood flow, albeit nonnutritionally, and thus theoretically prevents thrombosis due to stasis in the repaired distal vessel. When limb loss seems inevitable, a trial of intraarterial tolazoline is justified.
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PMID:Devastating distal arterial trauma and continuous intraarterial infusion of tolazoline. 640 43

To counter the paucity of documention on thromboembolic disorders caused by oral contraceptives (OC), a case study is presented describing the incidence of occlusion of arteria centralis retinae in a 24-year old woman after prolonged use of an OC, Bisecurin. She had taken Bisecurin for 4.5 years and had gained 20 kg during that time, but stopped usage 1 month before admission. She was hospitalized with severe deterioration of vision in the left eye. An eye examination indicated an edematous condition of the retina and reddening of the macula. Acuity of vision value for the left eye was .01 vs. 1.0 for the right, which was confirmed by fluorescein fundus angiography. Moderately decreased antithrombin III (AT III) activity was also ascertained. Treatment consisted of immediate retrobulbar injection with Tolazolin followed by Rheomacrodex, Cavinton infusions, B1 and B12 injections, Oradexon subconjunctival injection as well as vitamin B complex, Cavinton, and Colfarit tablets and a fat-free diet. Significant improvement of the left eye condition appeared 4 weeks later. Periodic follow-ups showed the healing of the condition around the macula; however, the patient suffered permanent damage to the retina due to the arterial occlusion above and below the macula. The disturbed lipid values of metabolism were also returned to normal, as borne out by normal dextrose loading results 8 months later (glucose tolerance was abnormal during examination at admission). The estrogen and progesterone components of OCs have been shown to reduce AT III levels, shorten heparin-thrombin coagulation time, increase fibrinogen levels, decrease HDL cholesterol levels, and produce excess TXA2 (thromboxan) resulting in vasoconstriction and thrombocyte aggregation. The risk of thrombosis is 6 times higher in OC users than in nonusers, although other susceptibility factors (obesity, diabetes, hypertension) also contribute to thrombosis.
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PMID:[Arterial occlusion in the ocular fundus induced by oral contraceptives]. 651 54

Clonidine poisoning usually causes depressed sensorium, hypotension, and bradycardia. Some patients manifest respiratory depression and miosis simulating narcotic overdose. Supportive care with judicious administration of intravenous fluids, occasionally supplemented by a dopamine infusion, usually reestablished adequate blood pressure. Tolazoline, an alpha-blocker, may reverse clonidine's effects should other efforts fail. Atropine should be used if bradycardia is hemodynamically significant. With massive overdose, clonidine's partial alpha-agonist properties may predominate, resulting in marked hypertension requiring cautious therapy. The experience at Parkland Memorial Hospital with clonidine overdose in six patients demonstrates the myriad of clinical presentations possible.
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PMID:Clonidine overdose: report of six cases and review of the literature. 701 72


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