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Russell McEvoy GM, Wells BN, Kiley ME, Kaur KK, Fraser GM. Dynamics of capillary blood flow responses to acute local changes in oxygen and carbon dioxide concentrations. Front Physiol 2022; 13:1052449. [PMID: 36561216 PMCID: PMC9764012 DOI: 10.3389/fphys.2022.1052449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/15/2022] [Indexed: 12/24/2022] Open
Abstract
Objectives: We aimed to quantify the magnitude and time transients of capillary blood flow responses to acute changes in local oxygen concentration ([O2]), and carbon dioxide concentration ([CO2]) in skeletal muscle. Additionally, we sought to quantify the combined response to both low [O2] and high [CO2] to mimic muscle microenvironment changes at the onset of exercise. Methods: 13 Sprague Dawley rats were anaesthetized, mechanically ventilated, and instrumented with indwelling catheters for systemic monitoring. The extensor digitorum longus muscle was blunt dissected, and reflected over a microfluidic gas exchange chamber in the stage of an inverted microscope. Four O2 challenges, four CO2 challenges, and a combined low O2 (7-2%) and high CO2 (5-10%) challenges were delivered to the surface with simultaneous visualization of capillary blood flow responses. Recordings were made for each challenge over a 1-min baseline period followed by a 2-min step change. The combined challenge employed a 1-min [O2] challenge followed by a 2-min change in [CO2]. Mean data for each sequence were fit using least-squared non-linear exponential models to determine the dynamics of each response. Results: 7-2% [O2] challenges decreased capillary RBC saturation within 2 s following the step change (46.53 ± 19.56% vs. 48.51 ± 19.02%, p < 0.0001, τ = 1.44 s), increased RBC velocity within 3 s (228.53 ± 190.39 μm/s vs. 235.74 ± 193.52 μm/s, p < 0.0003, τ = 35.54 s) with a 52% peak increase by the end of the challenge, hematocrit and supply rate show similar dynamics. 5-10% [CO2] challenges increased RBC velocity within 2 s following the step change (273.40 ± 218.06 μm/s vs. 276.75 ± 215.94 μm/s, p = 0.007, τ = 79.34s), with a 58% peak increase by the end of the challenge, supply rate and hematocrit show similar dynamics. Combined [O2] and [CO2] challenges resulted in additive responses to all microvascular hemodynamic measures with a 103% peak velocity increase by the end of the collection period. Data for mean responses and exponential fitting parameters are reported for all challenges. Conclusion: Microvascular level changes in muscle [O2] and [CO2] provoked capillary hemodynamic responses with differing time transients. Simulating exercise via combined [O2] and [CO2] challenges demonstrated the independent and additive nature of local blood flow responses to these agents.
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Yang SJ, Chen C, Zu CZ, Yang RM, Wang CC, Pu FF, Wang QT, Li XY, Zhao X, Cai DY. A rat model of vascular dementia for evaluating Chinese medicine prescriptions. Chin J Integr Med 2016:10.1007/s11655-015-2435-4. [PMID: 26956462 DOI: 10.1007/s11655-015-2435-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To develop a new model of vascular dementia for evaluating Chinese medicine prescriptions. METHODS Eighty-eight male Wistar rats were randomly divided into 4 groups. At d00, d42, d70, d98 (ni=20, 20, 24, 24) during fatty-feeding, rats in each group were further divided into 10 or 12 subgroups (ni=2), respectively. Lacunar stroke were replicated with the injection of thrombi which coagulated artificially from itself blood. The median lethal doses (LD50) were regressed from accumulative mortality in each geometric thrombus doses (k=0.75, 0.5, 0.85, 0.85), respectively. The degree of vascular dementia was evaluated as exploratory, learning and memorizing abilities. The median effective dose of thrombus for replicating rat model was regressed from dementia scores which were derived from the abilities. The linear correlation was regressed between the values of LD50 or effective dose (ED50) and the durations (days) of hypercholesterolemia. This model of vascular dementia was pathologically confirmed as the neural injuries from lacunar stroke in rats. RESULTS The hypercholesterolemia was indicated as elevated total cholesterol, triglyeerides low-density lipoprotein cholesterol, and decreased high-density lipoprotein cholesterol. The values of LD50 with its 95% confidence intervals (CI) were 1525.0 (1361.0-1709.0), 584.3 (490.1-696.6), 168.7 (163.7-173.8), or 62.4 (59.5-65.4) mg/mL, at d00, d42, d70, and d98, respectively. There is a linear regression between the values of LD50 and the durations of hypercholesterolemia (y=-15.33x+1390.0, r=0.963, P<0.05). The values of ED50 with its 95% CI were 528.8 (340.5-821.4), 217.0 (20.84-2259.0), 96.3 (23.4-402.6), or 47.0 (43.7-50.6) mg/mL from dementia score, at d00, d42, d70, and d98, respectively. There is a linear regression between the values of ED50 and the durations of hypercholesterolemia (y=-4.992x+484.2, r=0.965, P<0.05). The neural injuries were demonstrated as neural degeneration and necrosis. CONCLUSIONS For evaluating Chinese medicine, a model of vascular dementia in rats is set up with the lacunar stroke from self-thrombosis during hypercholesterolemia. This model from lacunar stroke is useful to investigate the pathogenesis and treatment of vascular dementia.
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Affiliation(s)
- Shi-Jun Yang
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Chen Chen
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Cheng-Zhe Zu
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Run-Mei Yang
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Cheng-Cheng Wang
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Fei-Fei Pu
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Qiu-Ting Wang
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Xiao-Ya Li
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Xin Zhao
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China
| | - Da-Yong Cai
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100193, China.
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Ishii K, Matsukawa K, Liang N, Endo K, Idesako M, Hamada H, Kataoka T, Ueno K, Watanabe T, Takahashi M. Differential contribution of ACh-muscarinic and β-adrenergic receptors to vasodilatation in noncontracting muscle during voluntary one-legged exercise. Physiol Rep 2014; 2:e12202. [PMID: 25413322 PMCID: PMC4255809 DOI: 10.14814/phy2.12202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/15/2014] [Accepted: 10/15/2014] [Indexed: 12/21/2022] Open
Abstract
We have demonstrated the centrally induced cholinergic vasodilatation in skeletal muscle at the early period of voluntary one-legged exercise and during motor imagery in humans. The purpose of this study was to examine whether central command may also cause β-adrenergic vasodilatation during the exercise and motor imagery. Relative changes in oxygenated hemoglobin concentration (Oxy-Hb) of bilateral vastus lateralis (VL) muscles, as index of tissue blood flow, and femoral blood flow to nonexercising limb were measured during one-legged cycling and mental imagery of the exercise for 1 min before and after propranolol (0.1 mg/kg iv). The Oxy-Hb of noncontracting muscle increased (P < 0.05) at the early period of exercise and the increase was sustained throughout exercise, whereas the Oxy-Hb of contracting muscle increased at the early period but thereafter decreased. We subtracted the Oxy-Hb response with propranolol from the control response in individual subjects to identify the propranolol-sensitive component of the Oxy-Hb response during exercise. In both noncontracting and contracting VL muscles, the increase in Oxy-Hb at the early period of one-legged exercise did not involve a significant propranolol-sensitive component. However, as the exercise proceeded, the propranolol-sensitive component of the Oxy-Hb response was developed during the later period of exercise. Propranolol also failed to affect the initial increases in femoral blood flow and vascular conductance of nonexercising leg but significantly attenuated (P < 0.05) their later increases during exercise. Subsequent atropine (10-15 μg/kg iv) abolished the initial increases in Oxy-Hb of both VL muscles. Mental imagery of the one-legged exercise caused the bilateral increases in Oxy-Hb, which were not altered by propranolol but abolished by subsequent atropine. It is likely that the rapid cholinergic and delayed β-adrenergic vasodilator mechanisms cooperate to increase muscle blood flow during exercise.
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Affiliation(s)
- Kei Ishii
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kanji Matsukawa
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Nan Liang
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kana Endo
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Mitsuhiro Idesako
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hironobu Hamada
- Department of Physical Analysis and Therapeutic Sciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tsuyoshi Kataoka
- Department of Health Care for Adults, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kazumi Ueno
- Department of Health Care for Adults, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tae Watanabe
- Department of Health Care for Adults, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Makoto Takahashi
- Department of Biomechanics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
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