Naphazoline intoxication managed with minimally invasive cardiac output monitoring

Naphazoline, a nonspecific alpha-adrenoceptor stimulant, is a potent vasoconstrictor used in nasal sprays, eye drops, and over-the-counter antiseptics. Naphazoline intoxication increases afterload by constricting the peripheral arteries, which can lead to complications including multiple organ failure. Although phentolamine, a nonselective alpha-adrenoceptor antagonist, and nicardipine, a calcium channel blocker, are used for the treatment of naphazoline intoxication, no established administration protocols currently exist. We present the case of a 32-year-old male with depression who ingested 150 mL of an antiseptic containing 0.1% naphazoline (equivalent to 150 mg of naphazoline). Five hours after ingestion, the patient was admitted to hospital exhibiting signs of naphazoline intoxication, such as bradycardia (46 beats/min), blood pressure of 166/122 mmHg, and peripheral cyanosis. We used the FloTrac™/EV1000™ system (Edwards Lifesciences, Irvine, CA, USA), a minimally invasive cardiac output monitoring system, to monitor systemic vascular resistance. The systemic vascular resistance index (SVRI) was elevated (4457 dyne.s/cm5/m2; nomal range: 1970-2390 dyne.s/cm5/m2) upon admission and initial treatment with continuous intravenous infusion of phentolamine led to SVRI normalization within 2 h. With the goal of maintaining SVRI normalization, continuous infusion with nicardipine was then started. At 10 h after treatment initiation, the nicardipine dose peaked at 9 mg/h (1.9 μg/kg/min). Treatment was discontinued 8 h later, and the patient was discharged on the fourth day without sequelae. In conclusion, the use of a minimally invasive cardiac output monitoring system to track vascular resistance can effectively guide the dosing of phentolamine or nicardipine in the treatment of naphazoline intoxication.

EFFECTIVENESS OF PHENTOLAMINE MESYLATE IN REVERSAL OF LOCAL ANESTHESIA: SYSTEMATIC REVIEW AND META-ANALYSIS

BACKGROUND

The aim of the present paper is to summarize the effectiveness of Phentolamine mesylate on the reversal of local anesthesia (LA).

METHODOLOGY

Seven electronic databases were searched for randomized clinical trials in patients who received LA (population) and either received a Phentolamine injection (intervention) after LA compared to placebo or sham (control) to cause a return of normal sensation (outcome). Risk of bias assessment was performed using Cochrane risk of bias assessment tool 2.0. The hazard ratio (HR) was calculated as the event (time to return to the normal sensation) was a time-dependent event, as well as the weighted mean difference (WMD), was computed. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the certainty of the evidence.

RESULTS

Ten studies met our inclusion criteria and were included in this review. After pooling the results quantitatively, the value of the HR in the tongue was 0.56 (95% CI: 0.41-0.75, P<.001); in lower lip, the value was 0.56 (95% CI: 0.38-0.83, P = .004) and for upper lip, the value was 0.50 (95% CI: 0.31-0.80, P = .004). The WMD for the time to return for normal sensation was -47.71 min for the tongue (95% CI: -73.63 to -21.80 min, P<.001), -73.29 min for lower lip (95% CI: -88.41 to -58.16 min, P<.001) and -86.86 min for upper lip (95% CI: -101.16 to -72.57 min, P<.001). There is a high certainty of evidence that patients who have been administered local anesthesia may achieve faster recovery of normal sensation in tongue, and moderate certainty of evidence for return of normal sensation in lower lip and upper lip, if Phentolamine was administered after the local anesthesia. The adverse effects were reported in a few studies and were minor, not necessitating any medical intervention.

CONCLUSIONS

Phentolamine might be a useful adjunct in patients who desire an earlier return of normal sensation and function after local anesthesia. Future research should be directed to study the cost-effectiveness or dental patient-reported outcomes of Phentolamine after local anesthetic injections.

phentolamine on event related potentials and cognitive functions in patients undergoing septoplasty: a randomized controlled trial

BACKGROUND

Postoperative cognitive dysfunction is a noteworthy complication of deliberate hypotensive anesthesia. The aim of this work was to compare the effect of deliberate hypotensive anesthesia using nitroglycerine versus phentolamine on event-related potentials and cognitive function in patients undergoing septoplasty surgery.

METHODS

This prospective randomized controlled trial was conducted on 80 patients indicated for septoplasty under general anesthesia; 40 patients received intra-operative Nitroglycerine and 40 patients received intra-operative Phentolamine. Cognitive assessment (using Paired Associate Learning test (PALT) and Benton Visual Retention test (BVRT)) and P300 recording were done for all included patients pre-operatively and one week postoperatively.

RESULTS

The scores of PALT and Benton BVRT significantly declined one week following surgery in both Nitroglycerine and Phentolamine groups. There was no statistically significant difference between Nitroglycerine and Phentolamine groups in the postoperative decline in either PALT or BVRT (P-value = 0.342, 0.662 respectively). The values of P300 latency showed a significant delay one week following surgery in both Nitroglycerine and Phentolamine groups (P-value ≤ 0.001, 0.001), but in Nitroglycerine group, the delay is significantly higher than in Phentolamine group (P-value = 0.003). The values of P300 amplitude significantly decreased one week following surgery in both Nitroglycerine and Phentolamine groups (P-value ≤ 0.001, 0.001), but there was no statistically significant difference between Nitroglycerine and Phentolamine groups (P-value = 0.099).

CONCLUSION

Phentolamine is preferred over nitroglycerin in deliberate hypotensive anesthesia because it has less harmful effect on cognitive function than nitroglycerin.

Association of periprocedural phentolamine infusion with favorable outcome in patients with chronic kidney disease and chronic coronary syndrome undergoing coronary catheterization: a prospective randomized controlled pilot study

BACKGROUND

Chronic kidney disease (CKD) is a major risk factor for contrast induced acute kidney injury (CI-AKI) in chronic coronary syndrome (CCS) patients undergoing coronary catheterization. We aimed to evaluate the efficacy of phentolamine in prevention of CI-AKI in CKD and CCS patients undergoing percutaneous coronary catheterization for diagnostic angiography ± stenting.

METHODS

Participants with CKD and CCS planned for percutaneous coronary catheterization were included, while participants with normal kidney functions were excluded. A consecutive sample of 107 participants (mean age 58.62 ± 8.96 years, 64.5% males) was selected, underwent diagnostic coronary angiography or percutaneous coronary intervention, and received either conventional CI-AKI prevention strategy (group 1) or periprocedural phentolamine and conventional CI-AKI prevention strategy (group 2).

RESULTS

The percentages of study participants who had CI-AKI were 82.9% for group 1 and 17.1% for group 2, respectively. The incidence rate of CI-AKI was significantly lower in group 2 versus group 1 (p <  0.001). The urine output (ml/kg) and the urine output (ml/hour) within 72 hours post procedure was significantly higher in group 2 versus group 1 (t(105) = - 0.69, p <  0.001, t(105) = - 52.46, p < 0.001, respectively), the peak change in serum creatinine and the percentage of change relative to the baseline serum creatinine at 72 hours post procedure was significantly lower in group 2 versus group 1 (t(102) = 0.2, p 0.018, t(102) = 23.54, p < 0.001, respectively), and the incidence rate of major adverse cardiac and cerebrovascular events within 90 days post procedure was significantly lower in group 2 versus group 1 (t(102) = 1.168, P < 0.001), respectively. There was a statistically significant association of periprocedural phentolamine infusion with prevention of CI-AKI (OR = 0.041, 95% CI 0.0149-0.1128, P < 0.0001).

CONCLUSION

Our study highlights the potential role of phentolamine for protection of the kidney in CKD patients planned for coronary catheterization.

TRIAL REGISTRATION

Pan African Clinical Trial Registry Number: PACTR202209493847741. Date of Trial Registration: 22/09/2022.

A randomized phase 2 clinical trial of phentolamine mesylate eye drops in patients with severe night vision disturbances

PURPOSE

Dim light vision disturbances (DLD) comprise a wide range of symptoms affecting the quality of vision at low illumination including glare, halos, and starbursts. This exploratory study investigated 1.0% phentolamine mesylate ophthalmic solution (PMOS) as a treatment to improve vision and image quality for patients with DLD.

METHODS

In this placebo-controlled, randomized, double-masked clinical trial, 24 adult patients with severe DLD were randomized in a 2:1 ratio to receive either one dose of PMOS or placebo. Subjects were eligible if they reported experiencing severe night vision difficulty that was not eliminated by distance spectacle correction and scored ≥0.3 log units below the normal range of contrast sensitivity assessed under mesopic conditions with glare at ≥2 spatial frequencies. Key efficacy outcomes were change from baseline in pupil diameter, contrast sensitivity, and visual acuity. Safety measures including intraocular pressure, conjunctival hyperemia, and systemic effects were also assessed.

RESULTS

Eight subjects were randomized to placebo (63% female; mean age 47 years) and 16 were randomized to PMOS (75% female; mean age 42 years). Mean (SD) pupil diameter of PMOS-treated subjects decreased significantly - 1.3 mm (0 to - 2.8 mm) with p < 0.0001. Mean contrast sensitivity with glare in PMOS-treated subjects improved significantly post-treatment at spatial frequencies 3, 6, 12, and 18 cycles per degree (p ≤ 0.03). PMOS also demonstrated improvements in the numbers of letters read for mesopic and photopic, high- and low-contrast visual acuity (LCVA). Importantly, a statistically greater proportion of PMOS-treated eyes registered mesopic LCVA 5 letter (69% vs. 31%, p = 0.029) and 10 letter (34% vs. 6%, p = 0.04) improvement, with a trend at 15 letters (19% vs. 0%, p = 0.16). PMOS was well tolerated with the only reported side effect being a mild increase in conjunctival hyperemia.

CONCLUSION

PMOS was well tolerated and effectively reduced pupil size with improvements in contrast sensitivity and visual acuity in adults with severe DLD. Future Phase 3 studies should be conducted to further evaluate its potential to treat DLD.

TRIAL REGISTRATION

The trial registration number is NCT04004507 (02/07/2019). Retrospectively registered.

Reversal Agents in Sedation and Anesthesia Practice for Dentistry

Reversal agents are defined as any drug used to counteract the pharmacologic effects of another drug. Several pharmacologic antagonists serve as essential drugs in the contemporary practices of sedation providers and anesthesiologists. Reversal or "antidote" drugs, such as flumazenil and naloxone, are often used in unintentional overdose situations involving significant benzodiazepine- and/or opioid-induced respiratory depression. Within the context of skeletal muscle relaxation, neostigmine and sugammadex are routinely used to reverse the effects of nondepolarizing neuromuscular blocking agents. In addition, the alpha-adrenergic antagonist phentolamine is used in dentistry as a local anesthetic reversal agent, decreasing its duration of action by inducing vasodilation. This review article discusses the pharmacology, uses, practical implications, adverse effects, and precautions needed for flumazenil, naloxone, neostigmine, sugammadex, and phentolamine within the context of sedation and anesthesia practice for dentistry.

Efficacy of phentolamine combined with ambroxol aerosol inhalation in the treatment of pediatric severe pneumonia and its effect on serum IL-10 and CRP levels

BACKGROUND

The aim of the present study was to determine the therapeutic effect of phentolamine combined with Ambroxol aerosol inhalation on pediatric severe pneumonia and its effect on serum interleukin-10 (IL-10) and C-reactive protein (CRP) levels.

METHODS

Eighty-five children with severe pneumonia treated in our hospital from November 2019 to November 2020 were selected as the research participants, and were divided into the routine group (n=41) and treatment group (n=44) according to odd and even admission numbers, respectively. Children in the first group received routine treatment, namely symptomatic treatment such as cough relief (e.g., expectorant) and defervescence, while those in the second group received phentolamine combined with Ambroxol aerosol inhalation. Clinical indexes of both groups before and after treatment were analyzed to determine the therapeutic effect of different treatment methods and serum IL-10 and CRP level changes.

RESULTS

There was no significant difference in general clinical data between the 2 groups (P>0.05). The duration of cough, fever, abnormal lung sound and lung shadow, and hospitalization time in the treatment group was significantly shorter than those in the routine group (P<0.001). The total clinical effective rate in the treatment group was significantly higher than that in the routine group (P<0.05). Forced vital capacity and peak expiratory flow rate levels were higher in both groups after treatment (P<0.05), and these were higher in the treatment group compared with the routine group after treatment (P<0.05). Serum IL-10 and CRP levels at T1 (2 days after treatment), T2 (5 days after treatment), and T3 (7 days after treatment) in the treatment group were significantly lower than those in the routine group (P<0.001). The total incidence of adverse reactions in the treatment group was significantly lower than that in the routine group (P<0.05).

CONCLUSIONS

Phentolamine combined with Ambroxol aerosol inhalation can significantly improve the clinical symptoms of children with severe pneumonia, reduce the body's inflammatory response, and improve lung function safely.

Clinical efficacy of phentolamine in the treatment of feeding intolerance in premature infants with low birth weight

Objective:

To discuss the clinical efficacy of phentolamine in the treatment of feeding intolerance in premature infants with low birth weight.

Methods:

Seventy-one low-birth-weight infants with feeding intolerance were randomly divided into the phentolamine group and the erythromycin group (38 patients and 33 patients, respectively). The infants were given basic treatment, such as gastric lavage, temporary fasting, nutritional support and abdominal massage. The phentolamine group was intravenously pumped with phentolamine as the basis of basic treatment, while the erythromycin group was given erythromycin as the basis of basic treatment. The time for gastrointestinal symptoms to disappear, the time the basic standard was reached, the time parenteral nutrition was used, the total time enteral feeding was implemented, the length of stay, and the increase in physical indexes according to the corrected gestational age of 40 weeks of the two groups were compared.

Results:

There was no significant difference between the phentolamine group and the erythromycin group in vomiting disappearance time or the increase in physical indicators at the corrected gestational age of 40 weeks (P>0.05), while the abdominal distension disappearance time, the time of restoration to birth weight, the time to reach the basic standard, the total time of parenteral nutrition, the total time of enteral feeding, and the length of stay in the phentolamine group were shorter than those in the erythromycin group, with significant differences (P<0.05).

Conclusion:

Phentolamine has a significant effect on alleviating symptoms and shortening the treatment time while treating feeding intolerance in premature infants with low birth weight, without adverse events, so it is worthy of clinical promotion.

The vasopressor action of angiotensin II (ANG II) in ball pythons (Python regius)

Angiotensin II (ANG II) is part of the renin-angiotensin system (RAS) in vertebrates and exert vasoconstriction in all species studied. The present study examines the vasopressor effect of ANG II in the ball python (Python regius), and examines whether ANG II exert its effect through direct angiotensin receptors or through an activation of α-adrenergic receptors. The studies were conducted in snakes with chronic arterial catheters that had recovered from anesthesia. In addition to demonstrating a clear and pronounced dose-dependent rise in arterial blood pressure upon repeated injections of boluses with ANG II (0.001-1 μg/kg), we demonstrate that the pressor response persisted following α-adrenergic blockade using the α-adrenergic antagonist phentolamine (2.5 mg/kg). Unfortunately, it proved impossible to block the ANG receptors using losartan (1, 3 or even 10 mg/kg). The pressor response to ANG II was associated with a significant rise in heart rate at the higher dosages, pointing to a resetting of the barostatic mechanism for heart rate regulation. The responses were similar in fasting and digesting pythons despite the expected rise in baseline values for blood pressure and heart rate of the digesting snakes.

Different Responses of Arterial Stiffness between the Aorta and the Iliofemoral Artery during the Administration of Phentolamine and Atenolol in Rabbits

Aim: The mechanism underlying the stiffness of the aorta and iliofemoral artery that is required to maintain blood pressure (BP) is unclear. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was defined by applying the cardio-ankle vascular index (CAVI). We compared changes in stiffness of the two arteries in response to reduced BP, due to the non-selective α adrenergic blocker phentolamine and the β ₁ adrenergic blocker atenolol, in rabbits.

Methods: Pressure waves at the origin (oA) and distal ends of the aorta (dA) and the distal end of the left femoral artery (fA) were recorded simultaneously using three pressure sensors in 25 anesthetized rabbits. Phentolamine (50 µg/kg/min) and atenolol (10 mg/kg/min) were infused for 2 min. The pulse wave velocity (PWV) in each artery was determined; aBeta, ifBeta, and whole Beta (aifBeta) were calculated by the following formula; Beta=2ρ/PP×ln(SBP/DBP)×PWV ² (ρ: blood density; SBP, SBP, and PP: systolic, diastolic, and pulse pressures, respectively).

Results: SBP and DBP at oA, dA, and fA decreased by the administration of phentolamine and atenolol, with and without decreased total peripheral vascular resistance. After phentramine infusion, cardiac output (CO), aBeta, and aifBeta increased, while ifBeta decreased. After infusion of atenolol, CO decreased, while aBeta, ifBeta, and aifBeta remained unchanged.

Conclusion: The contradictory reactions of aBeta and ifBeta to phentolamine suggest that the stiffness of the aorta and ilio-femoral artery is regulated separately during decreased BP induced by phentolamine, but not by atenolol.

[Efficacy and prognosis of phentolamine in the treatment of patients with myocardial injury due to sepsis]

Objective: To explore the effect of phenolamine on the outcome and prognosis of patients with myocardial injury due to sepsis. Methods: From January 2015 to December 2017, 62 septic patients with myocardial injury were randomly divided into study group (n=32) and control group (n=30). Two groups were given conventional treatment, while the study group was treated with phentolamine. The NT-pro brain natriuretic pepitide (NT-proBNP), cardiac troponin I (cTnI), lactate dehydrogenase (LDH), creatine kinase isoenzymes (CK-MB) and tumor necrosis factor (TNF)-α, high-sensitivity C-reactive protein (hs-CRP), interleukin (IL)-1β, IL-6 were detected at 0,12, 24, 48, 72 h and 7 d after hospitalization. And left ventricular ejection fraction (LVEF), e', E and A in each time period were observed. The 28 d survival rate and length of ICU stay were observed in both groups. The data were compared with single sample t test between the two groups. Results: After 12, 24, 48, 72 h and 7 d, NT-proBNP, cTnI, LDH, CK-MB, TNF-α, hs-CRP, IL-1β, IL-6 in the study group were all significantly lower than those in the control group (all P<0.05). The cardiac function indexes of LVEF, E/A and E/e' in the study group were all significantly improved when compared with those in the control group (all P<0.05). The length of ICU stay and 28-day mortality in the study group were significantly lower than those in the control group ((9.8±3.6) d vs (13.0±4.1) d, t=3.152, P=0.004; 21.9% vs 36.7%, χ(2)=5.078, P=0.021). Conclusion: Combined application of phentolamine can significantly improve the outcome of sepsis patients with myocardial injury and improve the survival rate.

The influence of adrenergic blockade in rats with apical periodontitis under chronic stress conditions

OBJECTIVE

To investigate the influence of chronic stress and adrenergic blockade in a rat model of apical periodontitis.

METHODS

Thirty-two Wistar rats were submitted to an animal model of periapical lesion and randomly divided into 4 groups (n = 8): no stress (NS); stress + saline solution (SS); stress + β-adrenergic blocker (Sβ); stress + α-adrenergic blocker (Sα). The SS, Sβ and Sα groups were submitted to an animal model of chronic stress for 28 days and received daily injections of saline solution, propranolol (β adrenergic blocker) and phentolamine (α adrenergic blocker), respectively. After 28 days the animals were euthanized and the following analyses were carried out: a) serum corticosterone levels through Radioimmunoassay; b) measurement of serum levels of IL-1B, IL-6, IL-10 and IL-17 by enzyme-linked immunosorbent assay (ELISA); c) volume of periapical bone resorption by micro-computed tomography; d) histomorphometric analysis by staining with hematoxylin and eosin; e) expression of β-AR, α-AR, receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) by immunohistochemistry; f) tartrate-resistant acid phosphatase (TRAP) staining; g) ex-vivo cytokine release followed by the stimulation with LPS in superfusion system, by ELISA.

RESULTS

SS group displayed significantly higher corticosterone levels than NS group (non-stressed). Higher IL-1β serum level was observed in the NS group (p < .05); compared to all stressed groups. Other cytokines were present in similar amounts in the serum of all groups. All groups presented similar periapical lesions. All groups presented moderate inflammatory infiltrate, without statistically significant differences between them. No differences were observed regarding β-AR, α-AR, Rank-L and OPG expression. The number of TRAP-positive cells was significantly decreased in the groups that received daily injections of adrenergic blockers. The IL-1β release followed LPS stimulation was significantly suppressed when the superfusion media contained propranolol (p < .05). Perfusion containing phentolamine induced a greater release of IL-10. TGF-β was significantly suppressed by phentolamine perfusion in the NS group (p < .05).

CONCLUSIONS

Chronic stress can significantly change the inflammatory cytokines release. Rank-L/OPG system and periapical lesion volume were not affected following the current method applied. The administration of adrenergic blockers was not able to modulate the inflammatory response but presented effectivity in reducing the number of osteoclasts in the periapical region.

Vasorelaxant effect of osthole on isolated thoracic aortic rings in rats

OBJECTIVE

To investigate the effect of osthole on isolated thoracic aortic rings, and to determine the potential mechanism of action.

METHODS

Thoracic aortas were isolated from Wistar rats, and were suspended in tissue organ chambers for vascular tension measurement. The effect of cumulative osthole (10－?, 10－?, 10－?, 10－?, and 10－? mol/L) on endothelium-intact and endothelium-denuded thoracic aortic rings pre-contracted with phenylephrine (PE, 10－? mol/L) or KCl (6 × 10－? mol/L) was recorded. Histomorphological changes of thoracic aorta were analyzed by hematoxylin-eosin. The effects of different osthole concentrations on endothelium-intact aortic rings, which were pre-inhibited with the non-selective nitric oxide synthase inhibitor L-Arg(NO2)-OMe·HCl (3 × 10－4 mol/L), endothelium-derived nitric oxide synthase inhibitor Nω-nitro-L-arginine (3 × 10－4 mol/L), guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-α] quinoxaline-1-one (10－5 mol/L), cyclooxygenase inhibitor indometacin (10－5 mol/L), and the Ca2+-activated potassium channel inhibitor tetraethylammonium nitrate (10－5 mol/L), and then contracted with PE, were examined. Aortic rings incubated with osthole (10－5 mol/L), phentolamine (10－5 mol/L), or verapamil (10－5 mol/L) in Ca2+-free Krebs-Henseleit solution (KHS) were stimulated with PE or KCl.

RESULTS

There was a dose-dependent increase in vasorelaxation of isolated thoracic aortic rings (both with and without endothelium) with increasing osthole concentration. Hematoxylin-eosin staining showed that osthole significantly improved thoracic aorta ring morphology. Compared with the control group, there were also significant differences after incubation with L-Arg(NO2)-OMe·HCl, Nω-nitro-L-arginine, and 1H-[1,2,4] oxadiazolo [4,3-α] quinoxaline-1-one (P < 0.05 for all). The relaxation rate of the rings in the osthole group incubated with indometacin and tetraethylammonium nitrate were similar to controls. In Ca2+-free KHS, the PE-induced contraction was similar between the osthole (4.37% ± 0.41%) and control (4.21% ± 1.33%) groups. However, after cumulative CaCl2 (0.5, 1, 1.5, 2, 2.5, and 3 mmol/L), the Ca2+-induced contraction was significantly inhibited in the osthole and phentolamine groups compared with controls (P < 0.05). After cumulative CaCl2 was added to Ca2+-free KHS (high K+ concentration), the contraction rate was significantly higher than both of the control and the osthole groups (P < 0.05). The contraction rate in the osthole group was higher than the verapamil group (P < 0.05).

CONCLUSION

Osthole has a vasorelaxant effect on isolated rat thoracic aortic rings, via inhibition of both receptor-operated and voltage-dependent Ca2+ channels in arterial smooth muscle, leading to decreased Ca2+ influx, and via inhibition of nitric oxide release on arterial endothelial cells.

Prothrombotic response to norepinephrine infusion, mimicking norepinephrine stress-reactivity effects, is partly mediated by α-adrenergic mechanisms

BACKGROUND

Stress-induced prothrombotic changes are mediated by the sympathetic nervous system and critically involved in mental triggering of acute coronary syndromes, but the underlying psychobiology is not fully understood. We tested the hypothesis that a norepinephrine (NE) infusion to mimic effects of stress-induced NE release on blood coagulation elicits prothrombotic changes and examined to what extent these would be mediated by an alpha-adrenergic mechanism.

METHODS AND RESULTS

In a single-blind placebo-controlled within-subjects design, 24 middle-aged, non-smoking, non-obese and normotensive men participated in three experimental trials with an interval between one and two weeks. Each trial applied two sequential infusions of 1 and 15 min duration with varying substances [i.e., saline as placebo, the non-specific α-blocker phentolamine (2.5 mg/min), and NE (5 μg/min)]: trial 1=saline + saline; trial 2=saline + NE, and trial 3=phentolamine + NE. Plasma levels of clotting factor VIII activity (FVIII:C), fibrinogen, and D-dimer were assessed from blood samples collected immediately before and 1 min and 20 min after infusion procedures. Compared to saline + saline, saline + NE induced increases over time in FVIII:C, fibrinogen, and D-dimer levels. With phentolamine + NE, fibrinogen levels remained increased compared to saline + saline, but changes in FVIII:C and D-dimer levels were no more different. Coagulation changes did not differ between saline + NE and phentolamine + NE.

CONCLUSIONS

NE infusion activates blood coagulation. The resulting prothrombotic state could be one psychobiological mechanism underlying mental triggering of acute coronary syndromes. Blockade of α-adrenergic receptors partly attenuated NE effects on coagulation and could be implied to have preventive potential in susceptible individuals.

Perioperative anesthetic management of intestinal pseudo-obstruction as a complication of pheochromocytoma

BACKGROUND

Intestinal pseudo-obstruction, which is a rare complication of pheochromocytoma, can be caused by hypersecreted catecholamines.

CASE PRESENTATION

A 45-year-old woman was admitted for local recurrence of pheochromocytoma complicated by intestinal pseudo-obstruction. The intestinal pseudo-obstruction showed poor response to α-adrenergic receptor blocker and she was scheduled for surgical resection of pheochromocytoma. The surgery was uneventfully accomplished with general anesthesia combined with epidural anesthesia. The latter was performed with the aim of not only perioperative pain management but also of promoting intestinal peristalsis. The anticipated effect for intestinal peristalsis was not apparent in the early postoperative phase. The abdominal symptoms were gradually relieved over the course of about 1 month.

CONCLUSIONS

For intestinal pseudo-obstruction induced by pheochromocytoma, although inhibition of the sympathetic system by epidural infusion of local anesthetics may be promising, short-term usage of epidural local anesthetics infusion did not provide a quick recovery after pheochromocytoma removal surgery.

Amitraz and its metabolite modulate honey bee cardiac function and tolerance to viral infection

The health and survival of managed honey bee (Apis mellifera) colonies are affected by multiple factors, one of the most important being the interaction between viral pathogens and infestations of the ectoparasitic mite Varroa destructor. Currently, the only effective strategy available for mitigating the impact of viral infections is the chemical control of mite populations. Unfortunately, the use of in-hive acaricides comes at a price, as they can produce sublethal effects that are difficult to quantify, but may ultimately be as damaging as the mites they are used to treat. The goal of this study was to investigate the physiological and immunological effects of the formamidine acaricide amitraz and its primary metabolite in honey bees. Using flock house virus as a model for viral infection, this study found that exposure to a formamidine acaricide may have a negative impact on the ability of honey bees to tolerate viral infection. Furthermore, this work has demonstrated that amitraz and its metabolite significantly alter honey bee cardiac function, most likely through interaction with octopamine receptors. The results suggest a potential drawback to the in-hive use of amitraz and raise intriguing questions about the relationship between insect cardiac function and disease tolerance.

Arterial relaxation is coupled to inhibition of mitochondrial fission in arterial smooth muscle cells: comparison of vasorelaxant effects of verapamil and phentolamine

Mitochondria are morphologically dynamic organelles which undergo fission and fusion processes. Our previous study found that arterial constriction was always accompanied by increased mitochondrial fission in smooth muscle cells, whereas inhibition of mitochondrial fission in smooth muscle cells was associated with arterial relaxation. Here, we used the typical vasorelaxants, verapamil and phentolamine, to further confirm the coupling between arterial constriction and mitochondrial fission in rat aorta. Results showed that phentolamine but not verapamil induced vasorelaxation in phenylephrine (PE)-induced rat thoracic aorta constriction. Verapamil, but not phentolamine, induced vasorelaxation in high K⁺ (KPSS)-induced rat thoracic aorta constriction. Pre-treatment with phentolamine prevented PE- but not KPSS-induced aorta constriction and pre-treatment with verapamil prevented both PE- and KPSS-induced aorta constriction. Transmission electron microscopy (TEM) results showed that verapamil but not phentolamine inhibited KPSS-induced excessive mitochondrial fission in aortic smooth muscle cells, and verapamil prevented both PE- and KPSS-induced excessive mitochondrial fission in aortic smooth muscle cells. Verapamil inhibited KPSS-induced excessive mitochondrial fission in cultured vascular smooth muscle cells (A10). These results further demonstrate that arterial relaxation is coupled to inhibition of mitochondrial fission in arterial smooth muscle cells.

[Effects of phentolamine on haemodynamics of patients with severe sepsis]

Objective: To explore the effects of phentolamine on hemodynamic of patients with severe sepsis . Methods: From January 2015 to August 2016, using random number table, 59 patients with severe sepsis were divided into research group and the control group by conventional treatment in Department of Emergency, the Second People's Hospital of Nanning City. The patients of the research group were given phentolamine injection. The CI, ITBVI, EVLWI, SVRI of the patients were monitored by PICCO on 6, 12, 24, 48, 72 h before and after treatment. Measuring clearance of blood lactic acid, lactic acid, comparing two groups of blood lactic acid, lactic acid clearance change tendency, 28 d survival rate and time of the two groups in the ICU of patients was observed. Results: CI, SVRI, ITBVI of the research group was increased obviously, and EVLWI decreased obviously(P<0.05 or P<0.01)12, 24, 48, 72 h after treatment. The levels of blood lactic acid, lactic acid clearancef the research group improved better than that of the control group(P<0.05 or P<0.01) after treatment of 12, 24, 48, 72 h time points, especially lactate clearance increased significantly than the control group[(27.2±2.2) mmol/L vs(13.9±3.0) mmol/L, t=8.322, P=0.034]on 6 h. Time in ICU and 28 days rate of the research group was less than the control group[(9.8±3.6)d vs(13.0±4.1)d, P=0.004 ; (22.6% vs 35.7%, P=0.021)]. Conclusion: Phentolamine can significantly improve the early condition of hemodynamic and the survival rates of patients with severe sepsis.

Octopamine cyclic release and its modulation of visual sensitivity in crayfish

The biogenic amine octopamine (OA) modulates invertebrate behavior by changing neuronal responses from sensory inputs to motor outputs. However, the OA modulation of visual sensitivity and its possible coupling to diurnal cycles remains unexplored. Here we studied the diurnal variations in the OA levels in the hemolymph of the crayfish Procambarus clarkii, its release from the structures in the eyestalk and its modulation of the retinal light sensitivity. The hemolymph concentration of OA and its amino acid precursor tyrosine was measured by high-resolution liquid chromatography; OA varied along the 24-hcycle. The peak value appeared about 2h before the light offset which preceded the peak locomotor activity. OA was found in every structure of the eyestalk but displayed higher levels in the retina-lamina ganglionaris. Moreover, OA was released from isolated eyestalks at a rate of 92nmol/eyestalk/min and a calcium-dependent release was evoked by incubation in a high potassium solution. OA injected into dark-adapted crayfish or applied to the isolated retina at concentrations of 1, 10 and 100μM produced a proportionally increasing reduction in the amplitude of the photoreceptor light responses. These OA concentrations did not affect the position of the visual accessory pigments. Our results suggest that OA release in the crayfish eyestalk is coupled to the 24-hcycle to regulate the diurnal reduction of the photoreceptor sensitivity and to favor the expression of exploratory locomotion during the dark phase of the circadian cycle.

Statistical power analysis of cardiovascular safety pharmacology studies in conscious rats

Cardiovascular (CV) toxicity and related attrition are a major challenge for novel therapeutic entities and identifying CV liability early is critical for effective derisking. CV safety pharmacology studies in rats are a valuable tool for early investigation of CV risk. Thorough understanding of data analysis techniques and statistical power of these studies is currently lacking and is imperative for enabling sound decision-making.

METHODS

Data from 24 crossover and 12 parallel design CV telemetry rat studies were used for statistical power calculations. Average values of telemetry parameters (heart rate, blood pressure, body temperature, and activity) were logged every 60s (from 1h predose to 24h post-dose) and reduced to 15min mean values. These data were subsequently binned into super intervals for statistical analysis. A repeated measure analysis of variance was used for statistical analysis of crossover studies and a repeated measure analysis of covariance was used for parallel studies. Statistical power analysis was performed to generate power curves and establish relationships between detectable CV (blood pressure and heart rate) changes and statistical power. Additionally, data from a crossover CV study with phentolamine at 4, 20 and 100mg/kg are reported as a representative example of data analysis methods.

RESULTS

Phentolamine produced a CV profile characteristic of alpha adrenergic receptor antagonism, evidenced by a dose-dependent decrease in blood pressure and reflex tachycardia. Detectable blood pressure changes at 80% statistical power for crossover studies (n=8) were 4-5mmHg. For parallel studies (n=8), detectable changes at 80% power were 6-7mmHg. Detectable heart rate changes for both study designs were 20-22bpm.

DISCUSSION

Based on our results, the conscious rat CV model is a sensitive tool to detect and mitigate CV risk in early safety studies. Furthermore, these results will enable informed selection of appropriate models and study design for early stage CV studies.

Norepinephrine infusion with and without alpha-adrenergic blockade by phentolamine increases salivary alpha amylase in healthy men

BACKGROUND

Mental stress reliably induces increases in salivary alpha amylase (sAA), a suggested surrogate marker for sympathetic nervous system (SNS) reactivity. While stress-induced sAA increases correlate with norepinephrine (NE) secretion, a potential mediating role of noradrenergic mechanisms remains unclear. In this study, we investigated for the first time in humans whether a NE-stress-reactivity mimicking NE-infusion with and without alpha-adrenergic blockade by phentolamine would induce changes in sAA.

METHODS

In a single-blind placebo-controlled within-subjects design, 21 healthy men (29-66 years) took part in three different experimental trials varying in terms of substance infusion with a 1-min first infusion followed by a 15-min second infusion: saline-infusion (trial-1), NE-infusion (5 μg/min) without alpha-adrenergic blockade (trial-2), and with phentolamine-induced non-selective blockade of alpha1- and alpha2-adrenergic receptors (trial-3). Saliva samples were collected immediately before, during, and several times after substance infusion in addition to blood pressure and heart rate readings.

RESULTS

Experimental trials significantly differed in sAA reactivity to substance-infusion (p=.001) with higher sAA reactivity following NE-infusion with (trial-3; p=.001) and without alpha-adrenergic-blockade (trial-2; p=.004) as compared to placebo-infusion (trial-1); sAA infusion reactivity did not differ between trial-2 and trial-3 (p=.29). Effective phentolamine application was verified by blood pressure and heart rate infusion reactivity. Salivary cortisol was not affected by NE, either with or without alpha-adrenergic-blockade.

CONCLUSIONS

We found that NE-infusion stimulates sAA secretion, regardless of co-administered non-selective alpha-adrenergic blockade by phentolamine, suggesting that the mechanism underlying stress-induced sAA increases may involve NE.

Dissection of mechanisms that account for imidazoline-induced lowering of blood glucose in mice

Multiple mechanisms have been suggested to be responsible for the insulinotropic and blood glucose lowering effects of imidazoline compounds. This study was to unravel which mechanism predominantly accounts for glucose lowering by the prototypical imidazolines idazoxan and phentolamine. To this end, an α2-adrenoceptor agonist (UK14,304) and a KATP channel opener (diazoxide) were used to inhibit insulin release from isolated perifused mouse islets and to induce hyperglycaemia in conscious mice. Potentials of idazoxan and phentolamine to counteract these effects were examined in a comparative manner. In perifused islets, idazoxan increased insulin release only in the presence of the α2-agonist, whereas phentolamine strongly counteracted both inhibitors of insulin release. In vivo, a lower dose of idazoxan was necessary to ameliorate hyperglycaemia induced by the α2-agonist than by the KATP channel opener, indicating α2A-antagonism as the predominant mechanism of action (decrease in incremental area under the glucose curve induced by 0.1mg/kg idazoxan: under diazoxide, -3±7%, vs. under UK14,304, -34±9%, P<0.02). In contrast, identical doses of phentolamine were required to counteract hyperglycaemia induced by the two inhibitors of insulin release, implicating involvement of another mechanism beside α2A-antagonism (2mg/kg phentolamine: diazoxide, -11±8%, vs. UK14,304, -15±9%, ns; 4mg/kg phentolamine: diazoxide, -48±6%, vs. UK14,304, -48±8%, ns). The results show that imidazolines can lower blood glucose via more than one mechanism of action, with the relative contributions of the mechanisms varying considerably between individual compounds. Dissection of the involved mechanisms could help to develop imidazoline drugs for the treatment of type 2 diabetes.

RETRACTED: Effect of phentolamine on myocardial extracellular matrix of cardiac remodeling in rats

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the journal Editorial Office. The authors have plagiarized part of a paper that had already appeared in Chinese Journal of Arteriosclerosis 2014, 4, 362–366. article id: 1007–3949 (2014) 22-04-0362-05. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Noradrenergic mechanism involved in the nociceptive modulation of hippocampal CA3 region of normal rats

Norepinephrine (NE) is an important neurotransmitter in the brain, and regulates antinociception. However, the mechanism of action of NE on pain-related neurons in the hippocampal CA3 region is not clear. This study examines the effects of NE, phentolamine on the electrical activities of pain-excited neurons (PENs) and pain-inhibited neurons (PINs) in the hippocampal CA3 region of rats. Trains of electric impulses applied to the right sciatic nerve were used as noxious stimulation. The electrical activities of PENs or PINs in the hippocampal CA3 region were recorded by using a glass microelectrode. Our results revealed that, in the hippocampal CA3 region, the intra-CA3 region microinjection of NE decreased the pain-evoked discharged frequency and prolonged the discharged latency of PEN, and increased the pain-evoked discharged frequency and shortened discharged inhibitory duration (ID) of PIN, exhibiting the specific analgesic effect of NE. While intra-CA3 region microinjection of phentolamine produced the opposite response. It implies that phentolamine can block the effect of endogenous NE to cause the enhanced response of PEN and PIN to noxious stimulation. On the basis of above findings we can deduce that NE, phentolamine and alpha-adrenoceptor are involved in the modulation of nociceptive information transmission in the hippocampal CA3 region.

Successful Management of Phaeochromocytoma using Preoperative Oral Labetalol and Intraoperative Magnesium Sulphate: Report of four cases

Phaeochromocytoma is a rare neuroendocrine catecholamine-secreting tumour. This type of tumour poses multidimensional anaesthetic challenges as it has an unpredictable clinical course during surgical resection. The alpha-blocking agent phenoxybenzamine remained the mainstay in preoperative preparation before the introduction of beta-blocking agents. We report four cases operated between 2009-2012 at Sultan Qaboos University Hospital, Muscat, Oman. The cases were prepared with oral labetalol, as the alpha-blocking drug phenoxybenzamine was not immediately available. Responses to simulated stress were tested in the theatre before surgery. Anaesthesia was induced under invasive arterial pressure monitoring and magnesium sulphate infusion. Rare intraoperative surges in blood pressure during tumour manipulation were treated with sodium nitroprusside infusions and phentolamine boluses. All of the patients had an uneventful postoperative recovery. Preoperative treatment with labetalol has rarely been reported and can be considered as a potential therapeutic option with optimal patient monitoring if phenoxybenzamine is unavailable.

How long does it take phentolamine to reverse adrenaline-induced vasoconstriction in the finger and hand? A prospective, randomized, blinded study: The Dalhousie project experimental phase

At the Dalhousie Plastic Surgery Alumni Reunion at the Atlantic Plastic Surgery meeting in Halifax, Nova Scotia, in September 2001, 22 subjects, including 18 certified hand surgeons, were injected with 1.8 mL of 2% lidocaine with 1:100,000 adrenaline in three places in one finger of each hand. One hour later, the same sites of one hand were injected with phentolamine (1 mg in 1 mL), and the other hand was injected with saline. Subjects were blinded as to which hand received the phentolamine. It took an average of 85 min for the adrenaline-injected fingers to return to normal colour after phentolamine injection. It took an average of 320 min for the adrenaline-injected fingers to return to normal colour after saline injection (no phentolamine). We also observed that lidocaine with adrenaline provided an average of 549 min of anesthesia in nonphentolamine-injected fingers. Phentolamine consistently and reliably reversed adrenaline-induced vasoconstriction in the finger.