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Acetazolamide attenuates chemical-stimulated but not thermal-stimulated acute pain in mice. Acta Pharmacol Sin 2014; 35:41-7. [PMID: 24335844 DOI: 10.1038/aps.2013.149] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 09/18/2013] [Indexed: 11/08/2022] Open
Abstract
AIM Acetazolamide (AZA), a carbonic anhydrase (CA) inhibitor, has been found to alleviate inflammatory and neuropathic pain in rats. In the present study, we investigated the effects of AZA on thermal- and chemical-stimulated acute pain in mice and the possible mechanisms underlying the effects. METHODS Five acute pain models based on thermal and chemical stimuli were established to investigate the effects of AZA on different types of nociception in mice. The antinociceptive effects of methazolamide (another CA inhibitor) and diazepam (a positive allosteric modulator of GABAA receptor) were also examined. The drugs were administered either intraperitoneally (ip) or intrathecally. RESULTS AZA (50-200 mg/kg, ip) did not produce analgesia in two thermal-stimulated acute pain models, ie, mouse tail-flick and hot-plate tests. In contrast, AZA (50-200 mg/kg, ip) dose-dependently reduced paw licking time in both capsaicin and formalin tests in mice. A similar result was observed in a mouse acetic acid-induced writhing test. However, AZA (10 nmol/mouse, intrathecally) did not produce significant analgesia in the 3 chemical-stimulated acute pain models. In addition, methazolamide (50-200 mg/kg, ip) and diazepam (0.25-1.0 mg/kg, ip) did not produce significant analgesia in either thermal- or chemical-stimulated acute pain. CONCLUSION AZA produces analgesia in chemical-stimulated, but not thermal-stimulated acute pain in mice. The attenuation of chemical-stimulated acute pain by AZA may not be due to enhancement of GABAA receptor-mediated inhibition via inhibiting CA activity but rather a peripheral ion channel-related mechanism.
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Zahedi K, Barone S, Xu J, Soleimani M. Potentiation of the effect of thiazide derivatives by carbonic anhydrase inhibitors: molecular mechanisms and potential clinical implications. PLoS One 2013; 8:e79327. [PMID: 24260196 PMCID: PMC3832474 DOI: 10.1371/journal.pone.0079327] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/29/2013] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Carbonic anhydrase inhibitors (CAI) are mild diuretics, hence not widely used in fluid overloaded states. They are however the treatment of choice for certain non-kidney conditions. Thiazides, specific inhibitors of Na-Cl cotransport (NCC), are mild agents and the most widely used diuretics in the world for control of mild hypertension. HYPOTHESIS In addition to inhibiting the salt reabsorption in the proximal tubule, CAIs down-regulate pendrin, therefore leaving NCC as the major salt absorbing transporter in the distal nephron, and hence allowing for massive diuresis by the inhibitors of NCC in the setting of increased delivery of salt from the proximal tubule. EXPERIMENTAL PROTOCOLS AND RESULTS Daily treatment of rats with acetazolamide (ACTZ), a known CAI, for 10 days caused mild diuresis whereas daily treatment with hydrochlorothiazide (HCTZ) for 4 days caused hardly any diuresis. However, treatment of rats that were pretreated with ACTZ for 6 days with a combination of ACTZ plus HCTZ for 4 additional days increased the urine output by greater than 2 fold (p<0.001, n = 5) compared to ACTZ-treated animals. Sodium excretion increased by 80% in the ACTZ plus HCTZ group and animals developed significant volume depletion, metabolic alkalosis and pre-renal failure. Molecular studies demonstrated ∼75% reduction in pendrin expression by ACTZ. The increased urine output in ACTZ/HCTZ treated rats was associated with a significant reduction in urine osmolality and reduced membrane localization of AQP-2 (aquaporin2). CONCLUSIONS These results indicate that ACTZ down-regulates pendrin expression and leaves NCC as the major salt absorbing transporter in the distal nephron in the setting of increased delivery of salt from the proximal tubule. Despite being considered mild agents individually, we propose that the combination of ACTZ and HCTZ is a powerful diuretic regimen.
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Affiliation(s)
- Kamyar Zahedi
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Sharon Barone
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Jie Xu
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Manoocher Soleimani
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
- * E-mail:
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Jafarzadeh F, Field ML, Harrington DK, Kuduvalli M, Oo A, Kendall J, Desmond M, Mills K. Novel application of acetazolamide to reduce cerebrospinal fluid production in patients undergoing thoracoabdominal aortic surgery. Interact Cardiovasc Thorac Surg 2013; 18:21-6. [PMID: 24130087 DOI: 10.1093/icvts/ivt384] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Paraplegia is a rare but devastating complication, which may follow thoracoabdominal aortic surgery. Many adjuncts have been developed to reduce this risk including cerebrospinal fluid (CSF) drainage. Acetazolamide (carbonic anhydrase inhibitor) is a drug used to counteract mountain sickness and one of its effects is to reduce CSF production. Here, we report its first postoperative application in thoracoabdominal surgery with the aim of reducing cerebrospinal cord perfusion pressure and reducing risk of paraplegia. METHODS We retrospectively reviewed 6 patients who have been treated with this drug between 2011 and 2012 who were undergoing thoracoabdominal aortic surgery. Our indications were decided to include: (i) patients in whom a spinal drain could not be positioned; (ii) patients with blood-stained CSF; (iii) patients in whom the volume of CSF drained was outside guidelines; (iv) patients in whom CSF pressure was elevated; (v) patients with excessive vasopressor usage and (vi) patients with postoperative neurological dysfunction as measured by motor-evoked potentials or clinical examination. All were given 500 mg intravenous acetazolamide, not more than eight hourly, for a duration dependent on response. RESULTS In the 6 patients, 2 received a single dose of the drug and responded by an immediate drop in intracranial pressure (ICP) pressure. Of the 4 who received multiple doses of the drug, 1 had an immediate decline in ICP after each of the first six doses, while 3 had no discernable response. CONCLUSIONS This is the first report of the efficacy of acetazolamide in reducing CSF production and lowering ICP during thoracoabdominal aortic surgery. We believe that its use will be beneficial in the 6 patient groups described. Our experience suggests there are 'responders' and 'non-responders', the characteristics of whom are yet to be defined. Its efficacy in reducing not just CSF volume and ICP but also clinically relevant morbidity such as paraplegia, is the subject of a planned randomized controlled trial. This report serves to raise awareness of the possible efficacy of this drug when normal management strategies are limited or exhausted.
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Affiliation(s)
- Fatemeh Jafarzadeh
- Institute of Cardiovascular Medicine and Science, Thoracic Aortic Aneurysm Service, Liverpool Heart and Chest Hospital, Liverpool, UK
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Koul PA, Khan UH, Hussain T, Koul AN, Malik S, Shah S, Bazaz SR, Rashid W, Jan RA. High altitude pulmonary edema among "Amarnath Yatris". Lung India 2013; 30:193-8. [PMID: 24049253 PMCID: PMC3775198 DOI: 10.4103/0970-2113.116254] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Annual pilgrimage (Yatra) to the cave shrine of Shri Amarnath Ji' is a holy ritual among the Hindu devotees of Lord Shiva. Located in the Himalayan Mountain Range (altitude 13,000 ft) in south Kashmir, the shrine is visited by thousands of devotees and altitude sickness is reportedly common. MATERIALS AND METHODS More than 600,000 pilgrims visited the cave shrine in 2011 and 2012 with 239 recorded deaths. Thirty one patients with suspected altitude sickness were referred from medical centers en-route the cave to Sher-i-Kashmir Institute of Medical Sciences, a tertiary-care center in capital Srinagar (5,000 ft). The clinical features and the response to treatment were recorded. RESULTS Thirty-one patients (all lowlanders, 19 male; age 18-60 years, median 41) had presented with acute onset breathlessness of 1-4 days (median 1.9 d) starting within 12-24 h of a rapid ascent; accompanied by cough (68%), headache (8%), dizziness and nausea (65%). Sixteen patients had associated encephalopathy. Clinical features on admission included tachypnea (n = 31), tachycardia (n = 23), bilateral chest rales (n = 29), cyanosis (n = 22) and grade 2-4 encephalopathy. Hypoxemia was demonstrable in 24 cases and bilateral infiltrates on radiologic imaging in 29. Ten patients had evidence of high-altitude cerebral edema. All patients were managed with oxygen, steroids, nifedipine, sildenafil and other supportive measures including invasive ventilation (n = 3). Three patients died due to multiorgan dysfunction. CONCLUSIONS Altitude sickness is common among Amaranath Yatris from the plains and appropriate educational strategies should be invoked for prevention and prompt treatment.
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Affiliation(s)
- Parvaiz A Koul
- Department of Internal and Pulmonary Medicine, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India
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Müller WEG, Schröder HC, Schlossmacher U, Grebenjuk VA, Ushijima H, Wang X. Induction of carbonic anhydrase in SaOS-2 cells, exposed to bicarbonate and consequences for calcium phosphate crystal formation. Biomaterials 2013; 34:8671-80. [PMID: 23953824 DOI: 10.1016/j.biomaterials.2013.07.096] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 07/29/2013] [Indexed: 10/26/2022]
Abstract
Ca-phosphate/hydroxyapatite crystals constitute the mineralic matrix of vertebrate bones, while Ca-carbonate dominates the inorganic matrix of otoliths. In addition, Ca-carbonate has been identified in lower percentage in apatite crystals. By using the human osteogenic SaOS-2 cells it could be shown that after exposure of the cells to Ca-bicarbonate in vitro, at concentrations between 1 and 10 mm, a significant increase of Ca-deposit formation results. The crystallite nodules formed on the surfaces of SaOS-2 cells become denser and larger in the presence of bicarbonate if simultaneously added together with the mineralization activation cocktail (β-glycerophosphate/ascorbic acid/dexamethasone). In parallel, with the increase of Ca-deposit formation, the expression of the carbonic anhydrase-II (CA-II) gene becomes upregulated. This effect, measured on transcriptional level is also substantiated by immunohistological studies. The stimulatory effect of bicarbonate on Ca-deposit formation is prevented if the carbonic anhydrase inhibitor acetazolamide is added to the cultures. Mapping the surface of the Ca-deposit producing SaOS-2 cells by scanning electron microscopy coupled with energy-dispersive X-ray analysis revealed an accumulation of the signals for the element carbon and, as expected, also for phosphorus. Finally, it is shown that ortho-phosphate and hydrolysis products of polyphosphate inhibit CA-II activity, suggesting a feedback regulatory system between the CA-driven Ca-carbonate deposition and a subsequent inactivation of this process by ortho-phosphate. Based on the presented data we suggest that Ca-carbonate deposits act as bioseeds for a downstream Ca-phosphate deposition process. We propose that activators for CA, especially for CA-II, might be beneficial for the treatment of bone deficiency diseases.
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Affiliation(s)
- Werner E G Müller
- ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz, Germany.
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Abstract
Altitude physiology began with Paul Bert in 1878. Chronic mountain sickness (CMS) was defined by Carlos Monge in the 1940s in the Peruvian Andes as consisting of excess polycythemia. Hurtado et al performed studies in the Peruvian Andes in the 1950s to 1960s which defined acclimatization in healthy altitude natives, including polycythemia, moderate pulmonary hypertension, and low systemic blood pressure (BP). Electrocardiographic changes of right ventricular hypertrophy (RVH) were noted. Acclimatization of newcomers to altitude involves hyperventilation stimulated by hypoxia and is usually benign. Acute mountain sickness (AMS) in travelers to altitude is characterized by hypoxia-induced anorexia, dyspnea, headache, insomnia, and nausea. The extremes of AMS are high-altitude cerebral edema and high-altitude pulmonary edema. The susceptible high-altitude resident can lose their tolerance to altitude and develop CMS, also referred to as Monge disease. The CMS includes extreme polycythemia, severe RVH, excess pulmonary hypertension, low systemic BP, arterial oxygen desaturation, and hypoventilation.
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Affiliation(s)
- Thomas F Whayne
- Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky, Lexington, KY, USA
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Plataki M, Sands SA, Malhotra A. Clinical consequences of altered chemoreflex control. Respir Physiol Neurobiol 2013; 189:354-63. [PMID: 23681082 DOI: 10.1016/j.resp.2013.04.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/19/2013] [Accepted: 04/25/2013] [Indexed: 01/28/2023]
Abstract
Control of ventilation dictates various breathing patterns. The respiratory control system consists of a central pattern generator and several feedback mechanisms that act to maintain ventilation at optimal levels. The concept of loop gain has been employed to describe its stability and variability. Synthesizing all interactions under a general model that could account for every behavior has been challenging. Recent insight into the importance of these feedback systems may unveil therapeutic strategies for common ventilatory disturbances. In this review we will address the major mechanisms that have been proposed as mediators of some of the breathing patterns in health and disease that have raised controversies and discussion on ventilatory control over the years.
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Affiliation(s)
- Maria Plataki
- Department of Internal Medicine, Bridgeport Hospital, Yale New Haven Health, Bridgeport, CT, USA
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Salvi P, Revera M, Faini A, Giuliano A, Gregorini F, Agostoni P, Becerra CGR, Bilo G, Lombardi C, O'Rourke MF, Mancia G, Parati G. Changes in subendocardial viability ratio with acute high-altitude exposure and protective role of acetazolamide. Hypertension 2013; 61:793-9. [PMID: 23438935 DOI: 10.1161/hypertensionaha.111.00707] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High-altitude tourism is increasingly frequent, involving also subjects with manifest or subclinical coronary artery disease. Little is known, however, on the effects of altitude exposure on factors affecting coronary perfusion. The aim of our study was to assess myocardial oxygen supply/demand ratio in healthy subjects during acute exposure at high altitude and to evaluate the effect of acetazolamide on this parameter. Forty-four subjects (21 men, age range: 24-59 years) were randomized to double-blind acetazolamide 250 mg bid or placebo. Subendocardial viability ratio and oxygen supply/demand ratio were estimated on carotid artery by means of a validated PulsePen tonometer, at sea level, before and after treatment, and after acute and more prolonged exposure to high altitude (4559 m). On arrival at high altitude, subendocardial viability ratio was reduced in both placebo (from 1.63±0.15 to 1.18±0.17; P<0.001) and acetazolamide (from 1.68±0.25 to 1.35±0.18; P<0.001) groups. Subendocardial viability ratio returned to sea level values (1.65±0.24) after 3 days at high altitude under acetazolamide but remained lower than at sea level under placebo (1.42±0.22; P<0.005 versus baseline). At high altitude, oxygen supply/demand ratio fell both under placebo (from 29.6±4.0 to 17.3±3.0; P<0.001) and acetazolamide (from 32.1±7.0 to 22.3±4.6; P<0.001), its values remaining always higher (P<0.001) on acetazolamide. Administration of acetazolamide may, thus, antagonize the reduction in subendocardial oxygen supply triggered by exposure to hypobaric hypoxia. Further studies involving also subjects with known or subclinical coronary artery disease are needed to confirm a protective action of acetazolamide on myocardial viability under high-altitude exposure.
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Affiliation(s)
- Paolo Salvi
- Department of Cardiology, San Luca Hospital, IRCCS Istituto Auxologico Italiano, Milan, Italy
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Malagola R, Arrico L, Giannotti R, Pattavina L. Acetazolamide-induced cilio-choroidal effusion after cataract surgery: unusual posterior involvement. Drug Des Devel Ther 2013; 7:33-6. [PMID: 23378740 PMCID: PMC3556858 DOI: 10.2147/dddt.s38324] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Idiosyncratic reactions to a large number of drugs have been reported to cause choroidal detachment and secondary angle-closure glaucoma (ACG). We report a case of bilateral acute ACG and peculiar choroidal effusion following administration of oral acetazolamide immediately after cataract surgery. Few cases of acute secondary ACG with choroidal effusion and anterior shift of the lens-iris diaphragm have been associated with acetazolamide compared with other sulfonamides. As far as we are aware, posterior involvement with retinal folds and papillary edema due to acetazolamide has not been described before.
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Affiliation(s)
- Romualdo Malagola
- Department of Ophthalmology, University of Rome La Sapienza, Rome, Italy
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Harrison MF, Anderson PJ, Miller AD, O'Malley KA, Richert ML, Johnson JB, Johnson BD. Physiological variables associated with the development of acute mountain sickness at the South Pole. BMJ Open 2013; 3:bmjopen-2013-003064. [PMID: 23869103 PMCID: PMC3717461 DOI: 10.1136/bmjopen-2013-003064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Exposure to altitudes >2500 m can result in acute mountain sickness (AMS), a mild and usually self-limiting condition. Research has attempted to identify factors associated with developing AMS without controlling important factors related to the ascent or collecting a comprehensive set of variables. OBJECTIVES The Antarctic Study of Altitude Physiology (ASAP) investigated variables associated with the development of AMS in adults experiencing rapid passive transport to altitude by airplane. DESIGN Our prospective observational trial collected data, including personal history, anthropometrics, vital signs, blood samples and pulmonary function, at sea level and at altitude. Statistical analysis utilised independent sample t tests to investigate between-group differences (p<0.05) and a forward, step-wise binary logisitic regression analysis was performed. PARTICIPANTS Of 248 eligible ASAP participants, those who did not use acetazolamide (N=98) were included in the present analysis. PRIMARY OUTCOME MEASURES The diagnosis of AMS using the Lake Louise Symptom Score. RESULTS Analysis of participants not using acetazolamide (n=90) found 30 participants developed AMS and 60 participants did not. Estimated plasma volume decreased significantly at altitude (p=0.025) in the AMS group as compared with the No AMS group while body weight did not change (p=0.125). Serum sodium (p=0.045) and low-density lipoprotein (LDL) (p=0.049) levels were higher in the No AMS group. A logistic regression analysis emphasised the contributions of LDL and eosinophil levels in the development of AMS. CONCLUSIONS These results suggest that the body water regulation and inflammation are key factors in AMS development when all other factors such as the level of physical exertion during ascent, the rate and magnitude of ascent and the use of acetazolamide are controlled.
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Affiliation(s)
- Michael F Harrison
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
- Department of Emergency Medicine, Henry Ford Hospital, Detroit, Michigan, USA
| | - Paul J Anderson
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Andrew D Miller
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Kathy A O'Malley
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Maile L Richert
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Jacob B Johnson
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Bruce D Johnson
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
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Gonzales JU, Scheuermann BW. Effect of acetazolamide on respiratory muscle fatigue in humans. Respir Physiol Neurobiol 2013; 185:386-92. [DOI: 10.1016/j.resp.2012.08.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 08/22/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
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113
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Yang MT, Chien WL, Lu DH, Liou HC, Fu WM. Acetazolamide impairs fear memory consolidation in rodents. Neuropharmacology 2012; 67:412-8. [PMID: 23231808 DOI: 10.1016/j.neuropharm.2012.11.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 11/09/2012] [Accepted: 11/11/2012] [Indexed: 10/27/2022]
Abstract
Acetazolamide (AZ) is an carbonic anhydrase inhibitor, which has been used in the treatment of seizures, mountain sickness and glaucoma. Memory impairment by AZ has been reported in patient interviews; however, the related mechanism is unclear. We applied two fear conditioning paradigms, shuttle avoidance and passive avoidance, in both rats and mice to investigate this clinical anecdote. Adult Wistar rats receiving AZ 1 h before the shuttle avoidance test showed decreased avoidance rates, especially at high dosage. Adult ICR mice receiving AZ both before and after acquisition trials showed the decreased step-through latencies during the passive avoidance test. This impairment of fear memory was corroborated with decreased LTP by AZ in the amygdala. AZ only inhibited fear conditioning-induced ERK phosphorylation and had no effect on Akt phosphorylation. In conclusion, our study confirmed the adverse cognitive effect of AZ in animal and electrophysiological studies. In clinical practice, clinicians should be aware of this side effect in patients taking AZ. In addition, this inhibition of fear memory by AZ could potentially be applied to patients with posttraumatic stress disorder.
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Affiliation(s)
- Ming-Tao Yang
- Department of Pediatrics, Far Eastern Memorial Hospital, No. 21, Section 2, Nanya South Road, Banciao District, New Taipei City 220, Taiwan.
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Parati G, Revera M, Giuliano A, Faini A, Bilo G, Gregorini F, Lisi E, Salerno S, Lombardi C, Ramos Becerra CG, Mancia G, Salvi P. Effects of acetazolamide on central blood pressure, peripheral blood pressure, and arterial distensibility at acute high altitude exposure. Eur Heart J 2012; 34:759-66. [DOI: 10.1093/eurheartj/ehs140] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Donnini I, Nannucci S, Valenti R, Pescini F, Bianchi S, Inzitari D, Pantoni L. Acetazolamide for the prophylaxis of migraine in CADASIL: a preliminary experience. J Headache Pain 2012; 13:299-302. [PMID: 22367627 PMCID: PMC3356473 DOI: 10.1007/s10194-012-0426-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/12/2012] [Indexed: 11/28/2022] Open
Abstract
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited microangiopathy caused by NOTCH3 mutations. It is characterized by migraine, with or without aura, ischemic events, psychiatric and cognitive disturbances. There is no approved treatment for migraine prophylaxis in CADASIL, but acetazolamide has been anecdotally reported to be effective. We retrospectively reviewed our database of patients with a genetic diagnosis of CADASIL to identify how many of them were treated with acetazolamide for the prophylaxis of migraine. The efficacy and the tolerability of this treatment were checked looking at the clinic reports. Acetazolamide was prescribed in seven patients; the mean duration of treatment was 6 months, and the daily dose ranged from 125 to 500 mg. Three patients had a total and sustained remission, while in two patients a reduction in attacks and an improvement of the headache intensity were recorded. In one of these, acetazolamide was deliberately taken only during the migraine attack and the beneficial effect started 1 h after administration. In two patients, the drug did not produce any beneficial effect. Mild side effects were recorded in two patients. Our preliminary experience expands previous reports and confirms the possible efficacy of acetazolamide in CADASIL migraine. Based on these data, a randomized controlled trial seems worthy to be carried out to test the efficacy and safety of this drug.
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Affiliation(s)
- Ida Donnini
- Department of Neurological and Psychiatric Sciences, University of Florence, Largo Brambilla 3, Florence, Italy
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Martí-Carvajal AJ, Simancas-Racines D, Hidalgo R. Interventions for treating high altitude illness. Hippokratia 2012. [DOI: 10.1002/14651858.cd009567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Arturo J Martí-Carvajal
- Universidad Tecnológica Equinoccial; Facultad de Ciencias de la Salud Eugenio Espejo; Quito Ecuador
| | - Daniel Simancas-Racines
- Universidad Tecnológica Equinoccial; Facultad de Ciencias de la Salud Eugenio Espejo; Quito Ecuador
| | - Ricardo Hidalgo
- Universidad Tecnológica Equinoccial; Facultad de Ciencias de la Salud Eugenio Espejo; Quito Ecuador
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The genetics of altitude tolerance: the evidence for inherited susceptibility to acute mountain sickness. J Occup Environ Med 2011; 53:159-68. [PMID: 21270658 DOI: 10.1097/jom.0b013e318206b112] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE Acute mountain sickness (AMS) has become a significant environmental health issue as improvements in transportation, "environmental tourism," and resource development lure more people to the highlands. Whether there is a genetic contribution to AMS susceptibility is a central question in high-altitude medicine. This article provides a systematic review of the evidence supporting such an innate predisposition. METHODS Scientific literature databases were screened using the terms "acute mountain sickness/AMS" and "altitude illness" combined with the terms "DNA," "gene," "genetic," or "polymorphism." RESULTS Sixteen genes from a variety of pathways have been tested for association with AMS and variants in eight showed positive associations suggesting that AMS is an environmentally mediated polygenic disorder. CONCLUSIONS The data suggest that genotype contributes to capacity to rapidly and efficiently acclimatize to altitude; nevertheless, the mechanisms by which this occurs have yet to be elucidated.
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Julian CG, Subudhi AW, Wilson MJ, Dimmen AC, Pecha T, Roach RC. Acute mountain sickness, inflammation, and permeability: new insights from a blood biomarker study. J Appl Physiol (1985) 2011; 111:392-9. [PMID: 21636566 DOI: 10.1152/japplphysiol.00391.2011] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pathophysiology of acute mountain sickness (AMS) is unknown. One hypothesis is that hypoxia induces biochemical changes that disrupt the blood-brain barrier (BBB) and, subsequently, lead to the development of cerebral edema and the defining symptoms of AMS. This study explores the relationship between AMS and biomarkers thought to protect against or contribute to BBB disruption. Twenty healthy volunteers participated in a series of hypobaric hypoxia trials distinguished by pretreatment with placebo, acetazolamide (250 mg), or dexamethasone (4 mg), administered using a randomized, double-blind, placebo-controlled, crossover design. Each trial included peripheral blood sampling and AMS assessment before (-15 and 0 h) and during (0.5, 4, and 9 h) a 10-h hypoxic exposure (barometric pressure = 425 mmHg). Anti-inflammatory and/or anti-permeability [interleukin (IL)-1 receptor agonist (IL-1RA), heat shock protein (HSP)-70, and adrenomedullin], proinflammatory (IL-6, IL-8, IL-2, IL-1β, and substance P), angiogenic, or chemotactic biomarkers (macrophage inflammatory protein-1β, VEGF, TNF-α, monocyte chemotactic protein-1, and matrix metalloproteinase-9) were assessed. AMS-resistant subjects had higher IL-1RA (4 and 9 h and overall), HSP-70 (0 h and overall), and adrenomedullin (overall) compared with AMS-susceptible subjects. Acetazolamide raised IL-1RA and HSP-70 compared with placebo in AMS-susceptible subjects. Dexamethasone also increased HSP-70 and adrenomedullin in AMS-susceptible subjects. Macrophage inflammatory protein-1β was higher in AMS-susceptible than AMS-resistant subjects after 4 h of hypoxia; dexamethasone minimized this difference. Other biomarkers were unrelated to AMS. Resistance to AMS was accompanied by a marked anti-inflammatory and/or anti-permeability response that may have prevented downstream pathophysiological events leading to AMS. Conversely, AMS susceptibility does not appear to be related to an exaggerated inflammatory response.
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Affiliation(s)
- Colleen Glyde Julian
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, 12469 East 17 Place, Bldg 400, Aurora, CO 80045-0508, USA
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Synthesis and evaluation of new carbonic anhydrase inhibitors. Bioorg Med Chem 2011; 19:3221-8. [PMID: 21524585 DOI: 10.1016/j.bmc.2011.03.061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/25/2011] [Accepted: 03/26/2011] [Indexed: 11/22/2022]
Abstract
A series of new sulfamide derivatives have been synthesized, their structures were confirmed by (1)H NMR and ESI-MS. Some target compounds were assessed by the tool of Dock6, and inhibition effects of all the new compounds on carbonic anhydrase II have been investigated. In addition, some compounds have been investigated for their antihypoxic effects in mice. Results indicated that nine target compounds exhibit as effectively as acetazolamide and 10 compounds have more potent inhibition effects on carbonic anhydrase II than acetazolamide. Three of them (I-8, I-18 and I'-3) can prolong markedly the survival time of mice in hypoxia, which are worth carrying out further studies.
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Subudhi AW, Dimmen AC, Julian CG, Wilson MJ, Panerai RB, Roach RC. Effects of acetazolamide and dexamethasone on cerebral hemodynamics in hypoxia. J Appl Physiol (1985) 2011; 110:1219-25. [PMID: 21393464 DOI: 10.1152/japplphysiol.01393.2010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous attempts to detect global cerebral hemodynamic differences between those who develop headache, nausea, and fatigue following rapid exposure to hypoxia [acute mountain sickness (AMS)] and those who remain healthy have been inconclusive. In this study, we investigated the effects of two drugs known to reduce symptoms of AMS to determine if a common cerebral hemodynamic mechanism could explain the prophylactic effect within individuals. With the use of randomized, placebo-controlled, double-blind, crossover design, 20 healthy volunteers were given oral acetazolamide (250 mg), dexamethasone (4 mg), or placebo every 8 h for 24 h prior to and during a 10-h exposure to a simulated altitude of 4,875 m in a hypobaric chamber, which included 2 h of exercise at 50% of altitude-specific VO(2max). Cerebral hemodynamic parameters derived from ultrasound assessments of dynamic cerebral autoregulation and vasomotor reactivity were recorded 15 h prior to and after 9 h of hypoxia. AMS symptoms were scored using the Lake Louise Questionnaire (LLQ). It was found that both drugs prevented AMS in those who became ill on placebo (~70% decrease in LLQ), yet a common cerebral hemodynamic mechanism was not identified. Compared with placebo, acetazolamide reduced middle cerebral artery blood flow velocity (11%) and improved dynamic cerebral autoregulation after 9 h of hypoxia, but these effects appeared independent of AMS. Dexamethasone had no measureable cerebral hemodynamic effects in hypoxia. In conclusion, global cerebral hemodynamic changes resulting from hypoxia may not explain the development of AMS.
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Affiliation(s)
- Andrew W Subudhi
- Altitude Research Center, University of Colorado Anschutz Medical Campus, Colorado, USA.
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Abstract
High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-acclimatized individuals after rapid ascent to high altitude. The most common syndrome is acute mountain sickness (AMS) which usually begins within a few hours of ascent and typically consists of headache variably accompanied by loss of appetite, nausea, vomiting, disturbed sleep, fatigue, and dizziness. With millions of travelers journeying to high altitudes every year and sleeping above 2,500 m, acute mountain sickness is a wide-spread clinical condition. Risk factors include home elevation, maximum altitude, sleeping altitude, rate of ascent, latitude, age, gender, physical condition, intensity of exercise, pre-acclimatization, genetic make-up, and pre-existing diseases. At higher altitudes, sleep disturbances may become more profound, mental performance is impaired, and weight loss may occur. If ascent is rapid, acetazolamide can reduce the risk of developing AMS, although a number of high-altitude travelers taking acetazolamide will still develop symptoms. Ibuprofen can be effective for headache. Symptoms can be rapidly relieved by descent, and descent is mandatory, if at all possible, for the management of the potentially fatal syndromes of high-altitude pulmonary and cerebral edema. The purpose of this review is to combine a discussion of specific risk factors, prevention, and treatment options with a summary of the basic physiologic responses to the hypoxia of altitude to provide a context for managing high-altitude illnesses and advising the non-acclimatized high-altitude traveler.
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Abstract
With increasing altitude, there is a fall in barometric pressure and a progressive fall in the partial pressure of oxygen. Acclimatization describes the physiologic changes that help maintain tissue oxygen delivery and human performance in the setting of hypobaric hypoxemia. These changes include a marked increase in alveolar ventilation, increased hemoglobin concentration and affinity, and increased tissue oxygen extraction. In some individuals, these physiologic changes may be inadequate, such that the sojourn to altitude and the attendant hypoxia are complicated by altitude-associated medical illness. The rate of ascent, the absolute change in altitude, and individual physiology are the primary determinants whether illness will develop or not. The most common clinical manifestations of altitude illness are acute mountain sickness, high altitude pulmonary edema, and high altitude cerebral edema.
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Gertsch JH, Lipman GS, Holck PS, Merritt A, Mulcahy A, Fisher RS, Basnyat B, Allison E, Hanzelka K, Hazan A, Meyers Z, Odegaard J, Pook B, Thompson M, Slomovic B, Wahlberg H, Wilshaw V, Weiss EA, Zafren K. Prospective, double-blind, randomized, placebo-controlled comparison of acetazolamide versus ibuprofen for prophylaxis against high altitude headache: the Headache Evaluation at Altitude Trial (HEAT). Wilderness Environ Med 2010; 21:236-43. [PMID: 20832701 DOI: 10.1016/j.wem.2010.06.009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 06/09/2010] [Accepted: 06/09/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE High altitude headache (HAH) is the most common neurological complaint at altitude and the defining component of acute mountain sickness (AMS). However, there is a paucity of literature concerning its prevention. Toward this end, we initiated a prospective, double-blind, randomized, placebo-controlled trial in the Nepal Himalaya designed to compare the effectiveness of ibuprofen and acetazolamide for the prevention of HAH. METHODS Three hundred forty-three healthy western trekkers were recruited at altitudes of 4280 m and 4358 m and assigned to receive ibuprofen 600 mg, acetazolamide 85 mg, or placebo 3 times daily before continued ascent to 4928 m. Outcome measures included headache incidence and severity, AMS incidence and severity on the Lake Louise AMS Questionnaire (LLQ), and visual analog scale (VAS). RESULTS Two hundred sixty-five of 343 subjects completed the trial. HAH incidence was similar when treated with acetazolamide (27.1%) or ibuprofen (27.5%; P = .95), and both agents were significantly more effective than placebo (45.3%; P = .01). AMS incidence was similar when treated with acetazolamide (18.8%) or ibuprofen (13.7%; P = .34), and both agents were significantly more effective than placebo (28.6%; P = .03). In fully compliant participants, moderate or severe headache incidence was similar when treated with acetazolamide (3.8%) or ibuprofen (4.7%; P = .79), and both agents were significantly more effective than placebo (13.5%; P = .03). CONCLUSIONS Ibuprofen and acetazolamide were similarly effective in preventing HAH. Ibuprofen was similar to acetazolamide in preventing symptoms of AMS, an interesting finding that implies a potentially new approach to prevention of cerebral forms of acute altitude illness.
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Affiliation(s)
- Jeffrey H Gertsch
- Department of Neurosciences, University of California-San Diego School of Medicine, San Diego, CA 92103-8465, USA.
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The hypoxia-induced facilitation of augmented breaths is suppressed by the common effect of carbonic anhydrase inhibition. Respir Physiol Neurobiol 2010; 171:201-11. [PMID: 20382275 DOI: 10.1016/j.resp.2010.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/01/2010] [Accepted: 04/02/2010] [Indexed: 11/20/2022]
Abstract
The typical respiratory response to hypoxia includes a dramatic facilitation of augmented breaths (ABs) or 'sighs' in the breathing rhythm. We recently found that when acetazolamide treatment is used to promote CO(2) retention and counteract alkalosis during exposure to hypoxia, then the hypoxia-induced facilitation of ABs is effectively prevented. These results indicate that hyperventilation-induced hypocapnia/alkalosis is an essential factor involved in the hypoxia-induced facilitation of augmented breaths. However, acetazolamide is also known to decrease the sensitivity of the arterial chemoreceptors. Therefore, the question remains as to whether acetazolamide prevents the facilitation of ABs during hypoxia by offsetting the effects of respiratory alkalosis, or alternatively by suppressing carotid body afferent activity. In the present study, we addressed this question by studying the effects of treatment with an alternative carbonic anhydrase inhibitor, methazolamide, which has been reported to leave carotid body responsiveness to hypoxia intact. Respiratory variables were monitored before, during and after 2 days of methazolamide treatment (10 mg kg(-1) IP, bid) in unsedated and unrestrained adult male rats. Pre-treatment, the number of ABs observed in a 5 min observation window was 1.2 + or - 0.8 and 17.4 + or - 3.8 in room air and hypoxia, respectively. During methazolamide treatment, the facilitation of ABs in hypoxia was rapidly and reversibly suppressed such that ABs we no longer significantly more frequent than they were in room air. The present results demonstrate that the hypoxia-induced facilitation of ABs can be suppressed via the general effects of carbonic anhydrase inhibition, which are common to both acetazolamide and methazolamide. We discuss these results as they pertain to the mechanisms regulating augmented breath production, and the possible association between hypocapnia/alkalosis and sleep disordered breathing.
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Davies AJ, Kalson NS, Stokes S, Earl MD, Whitehead AG, Frost H, Tyrell-Marsh I, Naylor J. Determinants of summiting success and acute mountain sickness on Mt Kilimanjaro (5895 m). Wilderness Environ Med 2010; 20:311-7. [PMID: 20030437 DOI: 10.1580/1080-6032-020.004.0311] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To determine the incidence of acute mountain sickness (AMS), the frequency of summiting success, and the factors that affect these in trekkers on Kilimanjaro, one of the world's most summitted high-altitude peaks. METHODS The study group comprised 312 trekkers attempting Mt Kilimanjaro summit by the Marango Route. Trekkers ascended over 4 or 5 days along a fixed ascent profile, stopping at 3 huts on ascent (2700 m, 3700 m, and 4700 m) before attempting the summit. Researchers were stationed at each hut for 16 days. Each night we measured heart rate, respiratory rate, blood pressure, oxygen saturation, and Lake Louise Score. We recorded the highest altitude that trekkers reached on the mountain. RESULTS Of 181 complete sets of data, 111 (61%) trekkers reached the summit, and 139 (77%) developed AMS. Physiological results were not related to summit success. The incidence of AMS and summiting success were similar in those on the 4- or 5-day route. Trekkers on the 5-day route who used acetazolamide were less likely to develop AMS and more likely to summit than were those not taking acetazolamide (P = <.05); this difference was not present with trekkers on the 4-day route. CONCLUSIONS The risk of developing AMS is high on Mt Kilimanjaro. Although taking an extra day to acclimatize with the use of acetazolamide did provide some protection against AMS, ideally trekkers need a more gradual route profile for climbing this mountain.
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Affiliation(s)
- Andrew J Davies
- Manchester Altitude Research Society, University of Manchester Medical School, Manchester, UK.
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Stokes S, Kalson NS, Earl M, Whitehead AG, Tyrrell-Marsh I, Frost H, Davies A. Age is no barrier to success at very high altitudes. Age Ageing 2010; 39:262-5. [PMID: 20068217 DOI: 10.1093/ageing/afp246] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Suzy Stokes
- Clinical Education Centre, University Hospital of North Staffordshire, Stoke-on-Trent ST4 6QG, UK.
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Kiwull-Schöne HF, Li Y, Kiwull PJ, Teppema LJ. Methazolamide does not impair respiratory work performance in anesthetized rabbits. Am J Physiol Regul Integr Comp Physiol 2009; 297:R648-54. [DOI: 10.1152/ajpregu.00134.2009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In human medicine, the carbonic anhydrase (CA) inhibitor acetazolamide is used to treat irregular breathing disorders. Previously, we demonstrated in the rabbit that this substance stabilized closed-loop gain properties of the respiratory control system, but concomitantly weakened respiratory muscles. Among others, the highly diffusible CA-inhibitor methazolamide differs from acetazolamide in that it fails to activate Ca2+-dependent potassium channels in skeletal muscles. Therefore, we aimed to find out, whether or not methazolamide may exert attenuating adverse effects on respiratory muscle performance as acetazolamide. In anesthetized spontaneously breathing rabbits ( n = 7), we measured simultaneously the CO2 responses of tidal phrenic nerve activity, tidal transpulmonary pressure changes, and tidal volume before and after intravenous application of methazolamide at two mean (± SE) cumulative doses of 3.5 ± 0.1 and 20.8 ± 0.4 mg/kg. Similar to acetazolamide, low- and high-dose methazolamide enhanced baseline ventilation by 52 ± 10% and 166 ± 30%, respectively ( P < 0.01) and lowered the base excess in a dose-dependent manner by up to 8.3 ± 0.9 mmol/l ( P < 0.001). The transmission of a CO2-induced rise in phrenic nerve activity into volume and/or pressure and, hence, respiratory work performance was 0.27 ± 0.05 ml·kg−1·kPa·unit−1 under control conditions, but remained unchanged upon low- or high-dose methazolamide, at 0.30 ± 0.06 and 0.28 ± 0.07 ml·kg−1·kPa·unit−1, respectively. We conclude that methazolamide does not cause respiratory muscle weakening at elevated levels of ventilatory drive. This substance (so far not used for medication of respiratory diseases) may thus exert stabilizing influences on breathing control without adverse effects on respiratory muscle function.
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Bell HJ, Haouzi P. Acetazolamide suppresses the prevalence of augmented breaths during exposure to hypoxia. Am J Physiol Regul Integr Comp Physiol 2009; 297:R370-81. [DOI: 10.1152/ajpregu.00126.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Augmented breaths, or “sighs,” commonly destabilize respiratory rhythm, precipitating apneas and variability in the depth and rate of breathing, which may then exacerbate sleep-disordered breathing in vulnerable individuals. We previously demonstrated that hypocapnia is a unique condition associated with a high prevalence of augmented breaths during exposure to hypoxia; the prevalence of augmented breaths during hypoxia can be returned to normal simply by the addition of CO2to the inspired air. We hypothesized that counteracting the effect of respiratory alkalosis during hypocapnic hypoxia by blocking carbonic anhydrase would yield a similar effect. We, therefore, investigated the effect of acetazolamide on the prevalence of augmented breaths in the resting breathing cycle in five awake, adult male rats. We found a 475% increase in the prevalence of augmented breaths in animals exposed to hypocapnic hypoxia compared with room air. Acetazolamide treatment (100 mg/kg ip bid) for 3 days resulted in a rapid and potent suppression of the generation of augmented breaths during hypoxia. Within 90 min of the first dose of acetazolamide, the prevalence of augmented breaths in hypoxia fell to levels that were no greater than those observed in room air. On cessation of treatment, exposure to hypocapnic hypoxia once again caused a large increase in the prevalence of augmented breaths. These results reveal a novel means by which acetazolamide acts to stabilize breathing and may help explain the beneficial effects of the drug on breathing stability at altitude and in patients with central forms of sleep-disordered breathing.
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Miscio G, Milano E, Aguilar J, Savia G, Foffani G, Mauro A, Mordillo-Mateos L, Romero-Ganuza J, Oliviero A. Functional involvement of central nervous system at high altitude. Exp Brain Res 2009; 194:157-62. [PMID: 19221723 DOI: 10.1007/s00221-009-1729-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 01/27/2009] [Indexed: 11/24/2022]
Abstract
Acute mountain sickness is a common discomfort experienced by unacclimatized persons on ascent to high altitude. We tested the hypothesis that exposure to high altitude affects cortical excitability using transcranial magnetic stimulation. We specifically analyzed the motor cortex excitability in normal subjects at high altitude and in a control condition near sea level. Mean resting motor threshold (RMT) was significantly higher at high altitude than at sea level (69.3 +/- 10.4 versus 56.3 +/- 10.9%; P = 0.042). Mean short intracortical inhibition (SICI) was significantly lower at high altitude than at sea level (percentage of test motor-evoked potential = 79.3 +/- 19.8 versus 28.7 +/- 17.5%; P = 0.0004). Symptoms of acute mountain sickness correlated with resting motor threshold changes induced by high altitude (R 2 = 0.53, P = 0.037). SaO2 correlated with SICI changes induced by high altitude (R 2 = 0.45, P = 0.036). We suggest that high altitude deeply changes cortical excitability by affecting both inhibitory and excitatory circuits and that this is reflected in acute mountain sickness symptoms.
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Affiliation(s)
- Giacinta Miscio
- Department of Neurology and Neurorehabilitation, Istituto Auxologico Italiano (IRCCS), San Giuseppe Hospital, Piancavallo, Oggebbio (VB), Italy
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Ainslie PN, Duffin J. Integration of cerebrovascular CO2 reactivity and chemoreflex control of breathing: mechanisms of regulation, measurement, and interpretation. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1473-95. [PMID: 19211719 DOI: 10.1152/ajpregu.91008.2008] [Citation(s) in RCA: 398] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cerebral blood flow (CBF) and its distribution are highly sensitive to changes in the partial pressure of arterial CO(2) (Pa(CO(2))). This physiological response, termed cerebrovascular CO(2) reactivity, is a vital homeostatic function that helps regulate and maintain central pH and, therefore, affects the respiratory central chemoreceptor stimulus. CBF increases with hypercapnia to wash out CO(2) from brain tissue, thereby attenuating the rise in central Pco(2), whereas hypocapnia causes cerebral vasoconstriction, which reduces CBF and attenuates the fall of brain tissue Pco(2). Cerebrovascular reactivity and ventilatory response to Pa(CO(2)) are therefore tightly linked, so that the regulation of CBF has an important role in stabilizing breathing during fluctuating levels of chemical stimuli. Indeed, recent reports indicate that cerebrovascular responsiveness to CO(2), primarily via its effects at the level of the central chemoreceptors, is an important determinant of eupneic and hypercapnic ventilatory responsiveness in otherwise healthy humans during wakefulness, sleep, and exercise and at high altitude. In particular, reductions in cerebrovascular responsiveness to CO(2) that provoke an increase in the gain of the chemoreflex control of breathing may underpin breathing instability during central sleep apnea in patients with congestive heart failure and on ascent to high altitude. In this review, we summarize the major factors that regulate CBF to emphasize the integrated mechanisms, in addition to Pa(CO(2)), that control CBF. We discuss in detail the assessment and interpretation of cerebrovascular reactivity to CO(2). Next, we provide a detailed update on the integration of the role of cerebrovascular CO(2) reactivity and CBF in regulation of chemoreflex control of breathing in health and disease. Finally, we describe the use of a newly developed steady-state modeling approach to examine the effects of changes in CBF on the chemoreflex control of breathing and suggest avenues for future research.
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Affiliation(s)
- Philip N Ainslie
- Department of Physiology, University of Otago, Dunedin, New Zealand.
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Xu J, Peng Z, Li R, Dou T, Xu W, Gu G, Liu Y, Kang Z, Tao H, Zhang JH, Ostrowski RP, Lu J, Sun X. Normoxic induction of cerebral HIF-1α by acetazolamide in rats: Role of acidosis. Neurosci Lett 2009; 451:274-8. [DOI: 10.1016/j.neulet.2009.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 01/05/2009] [Accepted: 01/06/2009] [Indexed: 11/28/2022]
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van Patot MCT, Leadbetter G, Keyes LE, Maakestad KM, Olson S, Hackett PH. Prophylactic Low-Dose Acetazolamide Reduces the Incidence and Severity of Acute Mountain Sickness. High Alt Med Biol 2008; 9:289-93. [DOI: 10.1089/ham.2008.1029] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Martha C. Tissot van Patot
- Department of Anesthesiology, University of Colorado Denver, Aurora, Colorado
- Altitude Research Center, Division of Emergency Medicine, Department of Surgery, University of Colorado Denver, Aurora, Colorado
| | - Guy Leadbetter
- Department of Exercise Physiology, Mesa State College, Grand Junction, Colorado
| | - Linda E. Keyes
- Altitude Research Center, Division of Emergency Medicine, Department of Surgery, University of Colorado Denver, Aurora, Colorado
| | - Kirsten M. Maakestad
- Department of Family and Community Medicine, University of Missouri, Columbia, Missouri
| | - Sheryl Olson
- Institute for Altitude Medicine, Telluride, Colorado
| | - Peter H. Hackett
- Altitude Research Center, Division of Emergency Medicine, Department of Surgery, University of Colorado Denver, Aurora, Colorado
- Institute for Altitude Medicine, Telluride, Colorado
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Rivera-Ch M, Huicho L, Bouchet P, Richalet JP, León-Velarde F. Effect of acetazolamide on ventilatory response in subjects with chronic mountain sickness. Respir Physiol Neurobiol 2008; 162:184-9. [DOI: 10.1016/j.resp.2008.06.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 06/05/2008] [Accepted: 06/09/2008] [Indexed: 11/16/2022]
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Kayser B, Hulsebosch R, Bosch F. Low-dose acetylsalicylic acid analog and acetazolamide for prevention of acute mountain sickness. High Alt Med Biol 2008; 9:15-23. [PMID: 18331216 DOI: 10.1089/ham.2007.1037] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Analgesic drugs like acetylsalicylic acid, paracetamol, and ibuprofen are frequently used by subjects suffering from headache of acute mountain sickness (AMS). It is not clear if the effect is due to analgesia or prevention of AMS. We performed a randomized controlled clinical trial comparing a low dose of an acetylsalicylic acid analog, calcium carbasalate (380 mg /day), to placebo in a cohort of altitude-naïve subjects attempting a fast climb of Mt. Kilimanjaro (5896 m). A third noncontrolled open arm was proposed-the usual recommended preventive treatment of acetazolamide 500 mg/day. Of 93 potential participants, 44 chose prevention with acetazolamide, 18 refused participation, 15 received calcium carbasalate, and 16 received placebo. Mean age was 39 +/- 9 (SD) yr and 15% were female. AMS was quantified by the Lake Louise Symptom Score and physician assessment. Calcium carbasalate at 380 mg/day did not have any preventive effect on AMS and did not have any effect on the prevalence and intensity of headache. Event rate of AMS in the pooled carbasalate-placebo group was 84% and 55% in the acetazolamide group. The number needed to treat (NNT) at 500 mg/day of acetazolamide was 3. One subject on acetazolamide developed high altitude cerebral edema and was treated with dexamethasone, oxygen, and descent by evacuation. In conclusion, low-dose calcium carbasalate is not effective for prevention of AMS. In addition, these results corroborate the contention that in typical steep climbing profile settings, such as used by commercial enterprise on Mt. Kilimanjaro, acetazolamide 500 mg/day may not be sufficient to prevent AMS or to sufficiently reduce symptom intensity in almost half of subjects.
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Affiliation(s)
- Bengt Kayser
- Institute of Movement Sciences and Sports Medicine, Faculty of Medicine, University of Geneva, Switzerland.
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138
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Plant T, Aref-Adib G. Travelling to new heights: practical high altitude medicine. Br J Hosp Med (Lond) 2008; 69:348-52. [DOI: 10.12968/hmed.2008.69.6.29626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tracie Plant
- Birmingham University Medical School, Birmingham B15 2TT and
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139
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Sun XC, Li J, Cui M, Bonanno JA. Role of carbonic anhydrase IV in corneal endothelial HCO3- transport. Invest Ophthalmol Vis Sci 2008; 49:1048-55. [PMID: 18326729 DOI: 10.1167/iovs.07-1188] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Carbonic anhydrase activity has a central role in corneal endothelial function. The authors examined the role of carbonic anhydrase IV (CAIV) in facilitating CO(2) flux, HCO(3)(-) permeability, and HCO(3)(-) flux across the apical membrane. METHODS Primary cultures of bovine corneal endothelial cells were established on membrane-permeable filters. Apical CAIV was inhibited by benzolamide or siRNA knockdown of CAIV. Apical CO(2) fluxes and HCO(3)(-) permeability were determined by measuring pH(i) changes in response to altering the CO(2) or HCO(3)(-) gradient across the apical membrane. Basolateral to apical (B-to-A) HCO(3)(-) flux was determined by measuring the pH of a weakly buffered apical bath in the presence of basolateral bicarbonate-rich Ringer solution. In addition, the effects of benzolamide and CAIV knockdown on steady state DeltapH (apical-basolateral compartment pH) after 4-hour incubation in DMEM were measured. RESULTS CAIV expression was confirmed, and CAIV was localized exclusively to the apical membrane by confocal microscopy. Both 10 microM benzolamide and CAIV siRNA reduced apparent apical CO(2) flux by approximately 20%; however, they had no effect on HCO(3)(-) permeability or HCO(3)(-) flux. The steady state apical-basolateral pH gradient at 4 hours was reduced by 0.12 and 0.09 pH units in benzolamide- and siRNA-treated cells, respectively, inconsistent with a net cell-to-apical compartment CO(2) flux. CONCLUSIONS CAIV does not facilitate steady state cell-to-apical CO(2) flux, apical HCO(3)(-) permeability, or B-to-A HCO(3)(-) flux. Steady state pH changes, however, suggest that CAIV may have a role in buffering the apical surface.
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Affiliation(s)
- Xing Cai Sun
- Indiana University, School of Optometry, Bloomington, Indiana 47405, USA
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Wright AD, Brearey SP, Imray CHE. High hopes at high altitudes: pharmacotherapy for acute mountain sickness and high-altitude cerebral and pulmonary oedema. Expert Opin Pharmacother 2007; 9:119-27. [DOI: 10.1517/14656566.9.1.119] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Fagenholz PJ, Murray AF, Gutman JA, Findley JK, Harris NS. New-Onset Anxiety Disorders at High Altitude. Wilderness Environ Med 2007; 18:312-6. [DOI: 10.1580/07-weme-br-102r1.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Brugniaux JV, Hodges ANH, Hanly PJ, Poulin MJ. Cerebrovascular responses to altitude. Respir Physiol Neurobiol 2007; 158:212-23. [PMID: 17544954 DOI: 10.1016/j.resp.2007.04.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/17/2007] [Accepted: 04/19/2007] [Indexed: 10/23/2022]
Abstract
The regulation of cerebral blood flow (CBF) is a complex process that is altered significantly with altitude exposure. Acute exposure produces a marked increase in CBF, in proportion to the severity of the hypoxia and mitigated by hyperventilation-induced hypocapnia when CO(2) is uncontrolled. A number of mediators contribute to the hypoxia-induced cerebral vasodilation, including adenosine, potassium channels, substance P, prostaglandins, and NO. Upon acclimatization to altitude, CBF returns towards normal sea-level values in subsequent days and weeks, mediated by a progressive increase in PO2, first through hyperventilation followed by erythropoiesis. With long-term altitude exposure, a number of mechanisms play a role in regulating CBF, including acid-base balance, hematological modifications, and angiogenesis. Finally, several cerebrovascular disorders are associated with altitude exposure. Existing gaps in our knowledge of CBF and altitude, and areas of future investigation include effects of longer exposures, intermittent hypoxia, and gender differences in the CBF responses to altitude.
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Affiliation(s)
- Julien V Brugniaux
- Department of Physiology & Biophysics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Swenson ER, Teppema LJ. Prevention of acute mountain sickness by acetazolamide: as yet an unfinished story. J Appl Physiol (1985) 2007; 102:1305-7. [PMID: 17194729 DOI: 10.1152/japplphysiol.01407.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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