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At least 379 records · Page 21Linked to original sources
PubMed1999

Phentolamine improves clinical outcome after balloon valvoplasty in neonates with severe pulmonary stenosis.

Two neonates with severe pulmonary stenosis deteriorated immediately after successful balloon valvoplasty as a result of increased infundibular obstruction. They were treated with beta-adrenoceptor blockers and intravascular expansion with limited success. Phentolamine was then given, resulting in dramatic improvement. The children could be weaned from the ventilator within hours of starting this new therapeutic modality.

Adrenergic alpha-Antagonists↗
PubMed2000

Re-dosing of prostaglandin-E1 versus prostaglandin-E1 plus phentolamine in male erectile dysfunction: a dynamic color power Doppler study.

During penile pharmacotesting, anxiety may overcome complete smooth muscle relaxation and lead to false positive diagnosis of organic male erectile dysfunction (ED). We tested the efficacy and safety of re-dosing of PGE1 alone versus combination of PGE, and the alpha1,2-blocker phentolamine (PHE) to improve an incomplete pharmaco-induced erection during color-power-Doppler (CPD) sonography. 116 consecutive impotent patients were submitted to CPD and injected with 10 microg PGE, plus audiovisual sexual stimulation. Clinical evaluation of rigidity and CPD parameters were normal in 26 patients while in the remaining they were upgraded in 15% and 35% after redosing of 10 microg PGE1 alone and 10 microg PGE1 plus 1 mg PHE, respectively (P < 0.05); furthermore, in these latter patients CPD studies showed increased visualisation of distal ramifications of helicine arterioles. The final diagnosis was changed in those patients who responded to re-dosing with no differences in the occurrence of prolonged erections between the two treatments. We conclude that re-dosing of PGE1/PHE mixture is a safe and effective procedure to maximize erectile response during dynamic CPD sonography and has a better diagnostic sensitivity than re-dosing of PGE1 alone.

Adrenergic alpha-Antagonists↗
PubMed1998

Vasoactive intestinal polypeptide and phentolamine mesylate administered by autoinjector in the treatment of patients with erectile dysfunction resistant to other intracavernosal agents.

OBJECTIVE: To study the effect of vasoactive intestinal polypeptide (VIP) and phentolamine mesylate (PM) on patients in whom previous intracavernosal therapy had failed. PATIENTS AND METHOD: The study comprised 70 consecutive patients attending a clinic for erectile dysfunction, in whom previous therapy with intracavernosal prostaglandin-E1 (20 microg and papaverine (30 mg) combined with 1 mg PM had failed. They were given intracavernosal injections, initially with 25 microg VIP/1 mg PM (VIP1) and if unsuccessful, 25 microg VIP/2 mg PM (VIP2). Both VIP1 and VIP2 were administered using a pre-filled ready-to-use autoinjector fitted with a 29 G needle. The patients were diagnosed as having spinal cord lesion (eight), diabetes (21), ischaemic heart disease (12), hypertension (six), other diagnoses (nine), or idiopathic causes (14). RESULT: Forty-seven (67%) of patients achieved erections sufficient for sexual intercourse (33 on VIP1 and 14 on VIP2), initially under clinical supervision and subsequently during home use. Minor side-effects were transient facial flushing in 37 (53%), truncal flushing in six (9%), bruising in 14 (20%) and pain from the injection needle in eight (11%). No patients reported priapism or other serious adverse events. CONCLUSION: The combination of VIP and PM at the dose used was a safe and effective treatment in patients in whom other therapies had failed.

Adolescent↗
PubMed1999

Treating men with predominantly nonpsychogenic erectile dysfunction with intracavernosal vasoactive intestinal polypeptide and phentolamine mesylate in a novel auto-injector system: a multicentre double-blind placebo-controlled study.

OBJECTIVE: To study the effect of intracorporeal injection (IC) of vasoactive intestinal polypeptide (VIP) and phentolamine mesylate (PM) on men with erectile dysfunction (ED) of nonpsychogenic aetiology. PATIENTS AND METHODS: The study comprised 236 men with primarily nonpsychogenic ED attending sexual dysfunction clinics at eight institutions. In an initial dose-assessment phase, the men were given IC injections of 25 micrograms VIP combined with PM 1.0 mg (VIP/P-1) or 2.0 mg (VIP/P-2) in a prefilled, single-use auto-injector. The main aetiologies of ED were arteriogenic (38), diabetes mellitus (DM) (39), neurogenic (35), mixed (90), and venous leakage (30). In a placebo-controlled phase, 171 patients were subsequently treated and self-administered up to 12 injections over a 6-month interval. RESULTS: In the dose-assessment phase there was an overall response rate of 82%, with responses by aetiology as follows: arteriogenic (82%), DM (85%), neurogenic (86%), mixed (80%), and venous leakage (77%). In a subgroup of 159 patients who withdrew from previous IC therapies for ED, 64% responded with an erection suitable for intercourse. Of the 171 patients treated in the placebo-controlled phase, 75% responded to VIP/P-1 and 12% to placebo (P<0.001); 66% responded to VIP/P-2 and 18% to placebo (P<0. 001), with a median duration of erection of 56 min. The principal adverse event was transient facial flushing accompanying 40% of 1711 injections. There was no pain after injection and one episode of priapism (0.06%); only seven patients withdrew because of adverse events. Over 88% and 92% of patients were satisfied with the drug and auto-injector, respectively. More than 85% of patients and 77% of partners reported an improved quality of life. CONCLUSION: The combination of VIP and PM at the dose used is a safe and effective means of treating male ED of primarily nonpsychogenic aetiology.

Adult↗
PubMed1983

Ergotamine-induced constriction of cranial arteriovenous anastomoses in dogs pretreated with phentolamine and pizotifen.

Previous investigations from our laboratory have shown that ergotamine causes a selective vasoconstriction in the carotid vascular bed of the dog and that the drug constricts arteriovenous anastomoses (AVAs) in cats and pigs. Since ergotamine can act via alpha-adrenergic or D-serotonergic receptors in certain vascular and non-vascular tissues, we have attempted to ascertain here if these receptors mediate the constriction of AVAs. Using radioactive microspheres of 15 microns diameter we found in the dog that about 40% of the carotid arterial blood is shunted to the venous side via AVAs. Ergotamine (2-20 micrograms X kg-1, i.v.) reduced total carotid blood flow to a larger extent in the AVA part than in the extracerebral part (muscles, ears, skin and fat). The cerebral component of carotid blood did not change. These results, confirming that ergotamine decreases arteriovenous shunting, show that the drug has a more selective action on the AVAs than on the arterioles. Pretreatment with phentolamine (0.5 mg X kg-1), pizotifen (0.5 mg X kg-1) or their combination did not effectively modify the responses to ergotamine. It is concluded that the vasoconstriction of cranial AVAs (and arterioles) by ergotamine does not appear to be primarily mediated by either alpha-adrenergic or D-serotonergic receptors. However, the role of atypical serotonin receptors has yet to be determined.

Animals↗
PubMed1991

Sexual, psychological, and marital impact of self-injection of papaverine and phentolamine: a long-term prospective study.

This prospective study assessed the long-term effects of self-injection of papaverine hydrochloride and phentolamine mesylate along several critical domains for 42 men and 26 partners. Over the course of one year, men were, on average, injecting themselves five times monthly, with 84% of these injections producing satisfactory erections. Treatment resulted in statistically significant improvements in quality of erection, sexual satisfaction, frequency of intercourse, and coital orgasm. The women also demonstrated significant improvement in sexual satisfaction, arousal, frequency of intercourse, and coital orgasm. Decreases in general psychiatric symptomatology were apparent for men but not for partners. The dropout rate was 57%. The common side effects of treatment were development of fibrotic nodules (26%), abnormal liver function values (30%), and bruising (19%). We conclude that self-injection should be considered among the accepted treatments for erectile dysfunction. It does appear to enhance the sexual lives of men and women when the treatment is efficacious and the couple is motivated to utilize it.

Adaptation, Psychological↗
PubMed1985

Paradoxical sleep deprivation and the immobility response in the rat: effects of desipramine and phentolamine.

A series of experiments was conducted on the presumption that instrumental deprivation of paradoxical sleep (PS) has an effect comparable with that of antidepressant drug treatment in a behavioral paradigm, Porsolt's forced swim test. After long-term PS deprivation, we studied the duration of immobility, which can be markedly reduced by antidepressant drugs, using both the platform and the pendulum technique. In addition to a small common effect for PS deprivation, differences confirming the platform-pendulum controversy were also detected. Nonspecific platform effects are considered to explain these differences. In a second experiment it was shown that the small PS deprivation effect can be enlarged by desipramine treatment, suggesting similarities in the underlying mechanisms. In the third experiment, just before the end of the deprivation, phentolamine, a drug that blocks the rebound of PS, was administered. It reduced the effect of pendulum PS deprivation, suggesting that PS propensity is an important factor in the reduction of duration of immobility.

Animals↗
PubMed1985

The use of two alpha blocking agents, phenoxybenzamine and phentolamine, in ointment and injection form to improve skin flap survival in rats.

Two alpha blocking agents, phenoxybenzamine and phentolamine, were tested to see if their use improved skin flap survival in rats. The agents were used in two ways: in local injections and topical applications. The results showed an increased duration of flap viability with both modalities, but the topical application was the most effective.

Administration, Topical↗
PubMed2000

Donor treatment with phentolamine mesylate improves machine preservation dynamics and early renal allograft function.

BACKGROUND: It has been suggested that pharmacologic conditioning of the donor before organ procurement may protect the renal allograft from injuries associated with the cold ischemic period. We compared the administration of two vasoactive agents before organ procurement to: (1) determine their influence on machine perfusion characteristics and (2) determine their impact on delayed graft function (DGF) in transplanted renal allografts. METHODS: Between January 1997 and December 1998, 150 kidneys were procured from heart-beating donors and preserved in our laboratory by machine perfusion (MP) or cold storage (CS). The following vasoactive agents were randomly administered to the donor 5 min before aortic cross clamp: phentolamine mesylate (PM) or hydralazine (H). The control groups received no donor conditioning. Kidneys were grouped as follows: (1) MP+PM, (2) MP+H, (3) MP, (4) CS+PM, (5) CS+H, (6) CS. 10 mg PM/50 kg donor weight was administered to the PM groups and 20 mg H/50 kg donor weight was administered to the H groups. DGF was defined as the need for dialysis within the first 7 days after the transplant. RESULTS: MP+PM increased renal flow by 12% and decreased renal resistance by 18% compared with the MP+H group, and increased renal flow by 23% and decreased renal resistance by 30% compared with the MP group. Moreover, the MP+PM group was associated with improved early allograft function. CONCLUSIONS: Donor treatment with PM immediately before aortic cross-clamp is associated with improved machine perfusion dynamics (renal flow and renal resistance) and lower incidence of DGF compared with donor treatment with H or no treatment. Moreover, MP of renal allografts was associated with improved early function compared with CS grafts.

Adult↗
PubMed1975

The effect of propranolol and phentolamine on serum gastrin concentration in response to respiratory acidosis in normal man.

Serum gastrin concentration and basal acid secretion were studied in normal subjects under the influence of respiratory acidosis induced by CO2 rebreathing. During the intragastric instillation of 100 ml/h 0.5 M bicarbonate a significant increase of gastrinaemia from 133 to 158 pg/ml (p less than 0.01) occurred in ten subjects during respiratory acidosis (pCO2 62 torr, pH 7.25). Under the intragastric instillation of 100 ml/h 0.1 N HCl the rise of gastrin concentration in response to CO2 rebreathing (pCO2 68 torr, pH 7.20) was not significant. The relationship between the decrease of pH and the increase of the gastrin concentration was shifted in the direction of a greater systemic acidosis compared to the results performed in the presence of a neutral intragastric pH. 50 mug/kg propranolol intravenously produced a decrease of gastrin concentrations from 145 to 127 pg/ml (p less than 0.01) and a total suppression of hypergastrinaemia in response to CO2 rebreathing, suggesting activation of beta-cell receptors in respiratory acidosis. The infusion of phentolamine in a dose of 0.6 to 1.8 mg/min. resulted in a rise of gastrin concentration from 140 to 165 pg/ml (p less than 0.01) which was not further elevated during respiratory acidosis. The basal acid secretion showed a significant rise in response to CO2 rebreathing, which was abolished by the administration of propranolol.

Acidosis, Respiratory↗
PubMed2006

Adrenaline-induced digital ischaemia reversed with phentolamine.

Adrenaline autoinjectors are widely prescribed for self-treatment of anaphylactic syndromes. Accidental misfire into digits can cause prolonged significant ischaemia with serious outcomes. Phentolamine is a readily available treatment, which is easily and safely given in the emergency setting.

Adrenergic alpha-Agonists↗
PubMed1977

Effect of phentolamine on perineal muscle EMG activity in paraplegia.

The effect of the alpha-adrenergic blocking agent, phentolamine, was studied on the perineal muscle EMG in 3 paraplegic patients. The drug reduced the EMG activity in these patients. This suggests that the normal suppression of external sphincter activity during micturition might be related to a reduction in the external sphincter activity supplied by the sympathetic system.

Electromyography↗
PubMed1986

Intracorporal injection of papaverine and phentolamine in the management of impotence.

Intracorporal injection of 0.5 ml papaverine (30 mg/ml) and phentolamine (2.5 mg/ml) was given to 144 patients presenting with various types of impotence. The high response rate (97%) precluded the use of this test to differentiate between types of impotence but provided patients with the choice of embarking on a self-injection programme. Of the 101 patients entering the programme 78 are continuing self-injection therapy with a mean follow-up of 6.5 months. The incidence of complications is low and patients are generally very satisfied with the treatment.

Adult↗
PubMed1987

Vascular responses to leukotriene B4, C4 and D4 following FPL 55712, indomethacin, saralasin, phentolamine and verapamil in the conscious rat.

The pressor and vascular permeability effects of leukotrienes B4 (LTB4), C4 and D4 were investigated in conscious unrestrained rats. Leukotrienes C4 and D4 (3.2-51 nmol kg-1 i.v.) caused an acute dose-dependent elevation of the mean arterial pressure, which was maximal after 2 min and returned to control levels within 14 min. Heart rate was significantly reduced by the higher doses of LTC4 and LTD4. LTB4 (up to a dose of 51 nmol kg-1) was essentially inactive. These effects of LTC4 and LTD4 were abolished by FPL 55712, a putative antagonist of sulphidopeptide leukotrienes and by verapamil, a calcium channel blocker. Indomethacin, phentolamine or saralasin pretreatment failed to modify the pressor response to LTC4 and LTD4. LTC4 and LTD4 furthermore caused an increase in haematocrit values, which was significantly attenuated by FPL 55712, indomethacin and verapamil. The present findings show that the pressor effect of LTC4 and LTD4 is not related to prostanoid release and can be reversed by calcium channel blockade; whereas the effect on vascular permeability seems to require the presence of both cyclo-oxygenase product(s) and calcium.

Animals↗
PubMed1975

The influence of phentolamine on the hyperglycaemic and lipolytic effects of ammonia in sheep.

Intravenous infusion over 30 min of ammonium chloride [10-1 g/kg b.w.] caused a significant increase of blood glucose and free fatty acids levels, and a similar effect was observed with adrenaline. Phentolamine [1 mg/kg b.w.] abolished the hyperglycaemic action of ammonium chloride but only slightly diminished the lipolytic effect. It is concluded that the ammonium ion influences carbohydrate metabolism chiefly by way of catecholamines and stimulation of alpha-adrenergic receptors, while tissue lipids are mobilized by ammonia by another route, possibley directly.

Ammonia↗
PubMed1985

Effect of phentolamine on the insulin, glucagon, and glucose responses to exercise in adrenal-denervated sheep.

Hyperglycemia and increased hepatic glucose output are characteristic responses to exercise in sheep. They appear to be due in part to alpha-adrenergic stimulation. To delineate the contributions of sympathetic innervation and adrenal catecholamines to the hormonal and metabolic responses to exercise, adrenal-denervated sheep were exercised with and without alpha-blockade (phentolamine treatment). Alpha blockade exaggerated the hyperinsulinemia during exercise (increment of 61 +/- 8 vs. 34 +/- 7 microU/mL for the control). This was associated with a reduction in glucose appearance (increments of 63 +/- 8 vs. 236 +/- 23 mumol/min, respectively). The metabolic clearance rates were not altered by alpha-blockade. It appears that both the adrenal catecholamines and adrenergic innervation to the pancreas contribute to the prevention of a rise in insulin concentrations during exercise in sheep. While this may not be essential for glucose appearance to rise during exercise, it appears necessary for an optimal response.

Adrenal Glands↗
PubMed1985

Phentolamine-resistant neurogenic constriction occurs in small arteries at higher frequencies.

The effect of the alpha 1, alpha 2-antagonist phentolamine (PTA) on neuromuscular transmission and exogenous norepinephrine (NE) was assessed in arteries of diminishing diameter possessing a substantial adventitiomedial junction adrenergic innervation in the rabbit ear, i.e., central ear artery (CEA), unstretched lumen diameter (ULD) approximately equal to 300 microns; main side branch (MSB) off the CEA (ULD approximately equal to 150 microns); and terminal branch (TB) off the MSB (ULD approximately equal to 75 microns). With increasing PTA concentrations, contractile responses to transmural nerve stimulation (TNS) were decreased proportionately less in TB than in MSB and CEA. PTA (4 X 10(-6) M, a competitive antagonist concentration) blocked the tetrodotoxin-sensitive TNS-induced contractions of CEA segments at 2, 4, and 8 Hz. The response at 8 Hz was reduced at least 98% in MSB and 86% in TB. However, responses to 8 Hz were not abolished in MSB and TB until 2 X 10(-5) and 3 X 10(-5) M PTA, respectively. PTA (3 X 10(-5) M) possessed nonspecific depressant properties in addition to its alpha-antagonist properties. We conclude that the sympathetic nervous system influences tone through alpha-adrenoceptors in the CEA and in the MSB and TB at lower frequencies. Responses in the MSB and TB at higher frequencies of nerve stimulation are mediated predominately through alpha-receptors. If the possibility of a nonadrenergic transmitter is discounted, the possibilities that the small PTA-resistant component of the neurogenic response is due to a high concentration of NE acting on alpha-adrenoceptors and/or a high threshold site cannot be distinguished.

Animals↗
PubMed1983

Dopamine, dobutamine, and phentolamine effects on pulmonary vascular mechanics.

The pressure-flow (P-Q) relationship of the pulmonary vasculature, in an isolated canine lobe perfused under classical zone II conditions, can be characterized by a rectilinear segment at high flow, a curvilinear segment at low flow, and a pulmonary arterial pressure (Ppa) that exceeds alveolar pressure at zero flow. This demonstrates the presence of critical closure in the pulmonary vascular bed. Effects of drugs on pulmonary vascular resistance (PVR) must take the normal P-Q relationship into account. We examined the effect of dopamine (D) and dobutamine (DB), alone and in combination with phentolamine (P), on the slope of the rectilinear segment of the P-Q curve (equivalent to vascular conductance), the extrapolated Ppa intercept (Ppai), and the Ppa at zero flow (Ppaz). Low-dose D (0.4-0.8 mg) and DB (1.0-5.0 mg) did not significantly alter any parameter from control. Higher-dose D (1.2-6.8 mg) and DB (13-38 mg) decreased vascular conductance 32.3 +/- 12.1 (SE) to 50.45 +/- 5.6% (P less than 0.05), and P alone increased conductance 12.0 +/- 2.6% (P less than 0.01) from control with no significant effect on Ppai or Ppaz. The change in conductance with D and DB alone was abolished when either drug was given in combination with P. Ppaz and Ppai decreased significantly from control with DB in combination with P when no significant effect on vascular conductance was noted. The results suggest that lung vessels determining changes in flow resistance are pharmacologically distinct from those subserving critical closure in the pulmonary vascular bed.

Animals↗