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Steele AR, Howe CA, Gibbons TD, Foster K, Williams AM, Caldwell HG, Brewster LM, Duffy J, Monteleone JA, Subedi P, Anholm JD, Stembridge M, Ainslie PN, Tremblay JC. Hemorheological, cardiorespiratory, and cerebrovascular effects of pentoxifylline following acclimatization to 3,800 m. Am J Physiol Heart Circ Physiol 2024; 326:H705-H714. [PMID: 38241007 DOI: 10.1152/ajpheart.00783.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 02/23/2024]
Abstract
Pentoxifylline is a nonselective phosphodiesterase inhibitor used for the treatment of peripheral artery disease. Pentoxifylline acts through cyclic adenosine monophosphate, thereby enhancing red blood cell deformability, causing vasodilation and decreasing inflammation, and potentially stimulating ventilation. We conducted a double-blind, placebo-controlled, crossover, counter-balanced study to test the hypothesis that pentoxifylline could lower blood viscosity, enhance cerebral blood flow, and decrease pulmonary artery pressure in lowlanders following 11-14 days at 3,800 m. Participants (6 males/10 females; age, 27 ± 4 yr old) received either a placebo or 400 mg of pentoxifylline orally the night before and again 2 h before testing. We assessed arterial blood gases, venous hemorheology (blood viscosity, red blood cell deformability, and aggregation), and inflammation (TNF-α) in room air (end-tidal oxygen partial pressure, ∼52 mmHg). Global cerebral blood flow (gCBF), ventilation, and pulmonary artery systolic pressure (PASP) were measured in room air and again after 8-10 min of isocapnic hypoxia (end-tidal oxygen partial pressure, 40 mmHg). Pentoxifylline did not alter arterial blood gases, TNF-α, or hemorheology compared with placebo. Pentoxifylline did not affect gCBF or ventilation during room air or isocapnic hypoxia compared with placebo. However, in females, PASP was reduced with pentoxifylline during room air (placebo, 19 ± 3; pentoxifylline, 16 ± 3 mmHg; P = 0.021) and isocapnic hypoxia (placebo, 22 ± 5; pentoxifylline, 20 ± 4 mmHg; P = 0.029), but not in males. Acute pentoxifylline administration in lowlanders at 3,800 m had no impact on arterial blood gases, hemorheology, inflammation, gCBF, or ventilation. Unexpectedly, however, pentoxifylline reduced PASP in female participants, indicating a potential effect of sex on the pulmonary vascular responses to pentoxifylline.NEW & NOTEWORTHY We conducted a double-blind, placebo-controlled study on the rheological, cardiorespiratory and cerebrovascular effects of acute pentoxifylline in healthy lowlanders after 11-14 days at 3,800 m. Although red blood cell deformability was reduced and blood viscosity increased compared with low altitude, acute pentoxifylline administration had no impact on arterial blood gases, hemorheology, inflammation, cerebral blood flow, or ventilation. Pentoxifylline decreased pulmonary artery systolic pressure in female, but not male, participants.
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Affiliation(s)
- Andrew R Steele
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States
| | - Katharine Foster
- Pulmonary and Critical Care, Veterans Affairs Loma Linda Healthcare System, Loma Linda, California, United States
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, United States
| | - Alexandra M Williams
- Department of Cellular & Physiological Sciences, Faculty of Medicine, University of British Columbia, Kelowna, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - L Madden Brewster
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Jennifer Duffy
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Justin A Monteleone
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Prajan Subedi
- Pulmonary and Critical Care, Veterans Affairs Loma Linda Healthcare System, Loma Linda, California, United States
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, United States
| | - James D Anholm
- Pulmonary and Critical Care, Veterans Affairs Loma Linda Healthcare System, Loma Linda, California, United States
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, United States
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Philip N Ainslie
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Joshua C Tremblay
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
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Suhocki PV, Doraiswamy PM. Cerebral venous biomarkers and veno-arterial gradients: untapped resources in Alzheimer's disease. Front Neurol 2024; 14:1295122. [PMID: 38239326 PMCID: PMC10794725 DOI: 10.3389/fneur.2023.1295122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 12/11/2023] [Indexed: 01/22/2024] Open
Abstract
Blood based biomarkers (BBB) derived from forearm veins for estimating brain changes is becoming ubiquitous in Alzheimer's Disease (AD) research and could soon become standard in routine clinical diagnosis. However, there are many peripheral sources of contamination through which concentrations of these metabolites can be raised or lowered after leaving the brain and entering the central venous pool. This raises the issue of potential false conclusions that could lead to erroneous diagnosis or research findings. We propose the use of simultaneous sampling of internal jugular venous and arterial blood to calculate veno-arterial gradient, which can reveal either a surplus or a deficit of metabolites exiting the brain. Methods for sampling internal jugular venous and arterial blood are described along with examples of the use of the veno-arterial gradient in non-AD brain research. Such methods in turn could help better establish the accuracy of forearm venous biomarkers.
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Affiliation(s)
- Paul V. Suhocki
- Duke University Hospital, Durham, NC, United States
- School of Medicine, Duke University, Durham, NC, United States
- Division of Interventional Radiology, Department of Radiology, Duke University Hospital, Durham, NC, United States
| | - P. Murali Doraiswamy
- School of Medicine, Duke University, Durham, NC, United States
- Duke Institute for Brain Sciences, School of Medicine, Duke University, Durham, NC, United States
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Duke University, Durham, NC, United States
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