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D'Souza AW, Yoo JK, Bhai S, Sarma S, Anderson EH, Levine BD, Fu Q. Attenuated peripheral oxygen extraction and greater cardiac output in women with posttraumatic stress disorder during exercise. J Appl Physiol (1985) 2024; 136:141-150. [PMID: 38031720 PMCID: PMC11219012 DOI: 10.1152/japplphysiol.00161.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 11/20/2023] [Accepted: 11/20/2023] [Indexed: 12/01/2023] Open
Abstract
Posttraumatic stress disorder (PTSD) is associated with an increased risk of developing cardiovascular disease, especially in women. Evidence indicates that men with PTSD exhibit lower maximal oxygen uptake (V̇o2max) relative to controls; however, whether V̇o2max is blunted in women with PTSD remains unknown. Furthermore, it is unclear what determinants (i.e., central and/or peripheral) of V̇o2max are impacted by PTSD. Therefore, we evaluated the central (i.e., cardiac output; Q̇c) and peripheral (i.e., arteriovenous oxygen difference) determinants of V̇o2max in women with PTSD; hypothesizing that V̇o2max would be lower in women with PTSD compared with women without PTSD (controls), primarily due to smaller increases in stroke volume (SV), and therefore Q̇c. Oxygen uptake (V̇o2), heart rate (HR), Q̇c, SV, and arteriovenous oxygen difference were measured in women with PTSD (n = 14; mean [SD]: 43 [11] yr,) and controls (n = 17; 45 [11] yr) at rest, and during an incremental maximal treadmill exercise test, and the Q̇c/V̇o2 slope was calculated. V̇o2max was not different between women with and without PTSD (24.3 [5.6] vs. 26.4 [5.0] mL/kg/min; P = 0.265). However, women with PTSD had higher Q̇c [P = 0.002; primarily due to greater SV (P = 0.069), not HR (P = 0.285)], and lower arteriovenous oxygen difference (P = 0.002) throughout exercise compared with controls. Furthermore, the Q̇c/V̇o2 slope was steeper in women with PTSD relative to controls (6.6 [1.4] vs. 5.7 [1.0] AU; P = 0.033). Following maximal exercise, women with PTSD exhibited slower HR recovery than controls (P = 0.046). Thus, despite attenuated peripheral oxygen extraction, V̇o2max is not reduced in women with PTSD, likely due to larger increases in Q̇c.NEW & NOTEWORTHY The current study indicates that V̇o2max is not different between women with and without PTSD; however, women with PTSD exhibit blunted peripheral extraction of oxygen, thus requiring an increase in Q̇c to meet metabolic demand during exercise. Furthermore, following exercise, women with PTSD demonstrate impaired autonomic cardiovascular control relative to sedentary controls. We interpret these data to indicate that women with PTSD demonstrate aberrant cardiovascular responses during and immediately following fatiguing exercise.
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Affiliation(s)
- Andrew W D'Souza
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Jeung-Ki Yoo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Salman Bhai
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Elizabeth H Anderson
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
- Veterans Affairs North Texas Health Care System, Dallas, Texas, United States
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
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Hamaoka T, Blaha C, Luck JC, Leuenberger UA, Sinoway LI, Cui J. Acute effects of sublingual nitroglycerin on cardiovagal and sympathetic baroreflex sensitivity. Am J Physiol Regul Integr Comp Physiol 2021; 321:R525-R536. [PMID: 34378422 DOI: 10.1152/ajpregu.00304.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of nitroglycerin (glyceryl trinitrate, GTN) on baroreflex sensitivity (BRS) are incompletely understood. Moreover, there are no reports evaluating the acute responses in both the sympathetic BRS (SBRS) and the cardiovagal BRS (CBRS) to the administration of sublingual GTN. We hypothesized that sublingual GTN modulates both CBRS and SBRS. In 10 healthy subjects, beat-to-beat heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded before and for 10 min after sublingual administration of GTN 0.4 mg. SBRS was evaluated from the relationship between spontaneous variations in diastolic BP and MSNA. CBRS was assessed with the sequence technique. These variables were assessed during baseline, during min 3rd - 6th (Post A) and 7th -10th min (Post B) after GTN administration. Two min after GTN administration, MSNA increased significantly and remained significantly elevated during recording. Compared to baseline, CBRS decreased significantly (Post A: 12.9 ± 1.6 to 7.1 ± 1.0 ms/mmHg, P < 0.05), while SBRS increased significantly (Post A: 0.8 ± 0.2 to 1.5 ± 0.2 units・beat-1・mmHg-1, P < 0.05) with an upward shift of the operating point. There were no differences in these variables between Post A and B. A clinical dose of GTN increased MSNA rapidly through effects on both CBRS and SBRS. These effects should be kept in mind when nitrates are used to clinically treat chest pain and acute coronary syndromes and used as vasodilators in experimental settings.
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Affiliation(s)
- Takuto Hamaoka
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Cheryl Blaha
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - J Carter Luck
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Urs A Leuenberger
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Lawrence I Sinoway
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Jian Cui
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
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Effect of thermal preconditioning on Hsp70 expression in the medulla oblongata and on hemodynamics during passive hyperthermia. Brain Res 2019; 1723:146404. [PMID: 31454515 DOI: 10.1016/j.brainres.2019.146404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 11/24/2022]
Abstract
A short-term episode of elevated core body temperature that induces Hsp70 expression (thermal preconditioning) may protect against heatstroke during subsequent hyperthermia. The protective effects of thermal preconditioning may involve several cellular and immunological mechanisms and improvements in baroreflex sensitivity. To substantiate the hypothesis that the protective effect of thermal preconditioning also occurs in conditions with intact thermoregulation, we examined the evolution of spontaneous cardiovagal baroreflex sensitivity and the protective effect of Hsp70 expression after thermal preconditioning in nonanesthetized Wistar-Kyoto rats with implanted telemetric transmitters. In the baroreflex centers of the medulla oblongata, thermal preconditioning induced Hsp70 in perineuronal and perivascular oligodendrocytes, microglia, and endothelial cells but not in neurons. The maximal Hsp70 expression was detected 4 h after preconditioning, but a significant number of Hsp70-positive cells was still present 72 h after preconditioning. Increased c-Fos expression in the neurons of baroreflex centers was detectable only 4 h after preconditioning. The mean values of cardiovagal baroreflex sensitivity did not show significant differences during the 72-hour follow-up period after thermal preconditioning. Similarly, cardiovascular variability measures of the autonomic nervous system activity were also not significantly affected by thermal preconditioning. During passive hyperthermia, thermal preconditioning had no statistically significant effect on thermoregulation and the onset of arterial pressure decline. Our data suggest that thermal preconditioning induces a glial type of Hsp70 expression in the baroreflex centers of the medulla oblongata. However, this response was not associated with cardiovagal baroreflex sensitization and protection against hemodynamic instability during passive hyperthermia.
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Turcani M, Ghadhanfar E. Biphasic changes in spontaneous cardiovagal baroreflex sensitivity during passive hyperthermia. Sci Rep 2019; 9:2586. [PMID: 30796280 PMCID: PMC6385277 DOI: 10.1038/s41598-019-39172-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/18/2019] [Indexed: 01/28/2023] Open
Abstract
Successful adaptation to passive hyperthermia requires continual adjustment of circulation, which is mediated mainly by the autonomic nervous system. The goal of this study was to explore the alterations in spontaneous cardiovagal baroreflex sensitivity (BRS) during exposure to a hot environment. To continuously follow changes in core body temperature (Tc), haemodynamics, and BRS, male Wistar-Kyoto rats were implanted with telemetric transmitters. BRS at an ambient temperature of 23 °C was not steady but oscillated with a maximum power in the range of 0.02–0.2 Hz. Exposure to hot air immediately shifted the distribution of BRS to higher values, although Tc remained unchanged (37.2 (0.3) °C), and the average BRS changed from 1.3 (0.3) to 3 (1.4) ms.mmHg−1, p < 0.0001. The degree of initial cardiovagal baroreflex sensitization explained 57% of the variability in the time to the onset of arterial pressure decline (p = 0.0114). With an increasing Tc (>38.8 (0.6) °C), BRS non-linearly declined, but haemodynamic parameters remained stable even above a Tc of 42 °C when the cardiovagal baroreflex was virtually non-operative. Abrupt full desensitization of the cardiovagal baroreflex with a muscarinic blocker did not induce arterial pressure decline. Our data indicate that a progressive decrease in BRS during passive hyperthermia does not induce haemodynamic instability. The positive association between initial cardiovagal baroreflex sensitization and the time to the onset of arterial pressure decline may reflect the potential protective role of parasympathetic activation during exposure to a hot environment.
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Affiliation(s)
- Marian Turcani
- Department of Physiology, Faculty of Medicine, Kuwait University, P. O. Box 24923, Safat, 13110, Kuwait.
| | - Elham Ghadhanfar
- Department of Physiology, Faculty of Medicine, Kuwait University, P. O. Box 24923, Safat, 13110, Kuwait
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Wesseling KH, Karemaker JM, Castiglioni P, Toader E, Cividjian A, Settels JJ, Quintin L, Westerhof BE. Validity and variability of xBRS: instantaneous cardiac baroreflex sensitivity. Physiol Rep 2018; 5:5/22/e13509. [PMID: 29180481 PMCID: PMC5704083 DOI: 10.14814/phy2.13509] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 11/24/2022] Open
Abstract
Spontaneous oscillations of blood pressure (BP) and interbeat interval (IBI) may reveal important information on the underlying baroreflex control and regulation of BP We evaluated the method of continuously measured instantaneous baroreflex sensitivity by cross correlation (xBRS) validating its mean value against the gold standard of phenylephrine (Phe) and nitroprusside (SNP) bolus injections, and focusing on its spontaneous changes quantified as variability around the mean. For this purpose, we analyzed data from an earlier study of eight healthy males (aged 25-46 years) who had received Phe and SNP in conditions of baseline and autonomic blocking agents: atropine, propranolol, and clonidine. Average xBRS corresponds well to Phe/SNP-BRS, with xBRS levels ranging from 1.2 (atropine) to 102 msec/mmHg (subject asleep under clonidine). Time shifts from BP- to IBI-signal increased from ≤1 sec (maximum correlations within the current heartbeat) to 3-5 sec (under atropine). Plotted on a logarithmic vertical scale, xBRS values show 40% variability (defined as SD/mean) over the whole range in the various conditions, except twice when the subjects had fallen asleep and it dropped to 20%. The xBRS oscillates at frequencies of 0.1 Hz and lower, dominant between 0.02-0.05 Hz. Although xBRS is the result of IBI/BP-changes, no linear coherence was found in the cross-spectra of the xBRS-signal and IBI or BP We speculate that the level of variability in the xBRS-signal may act as a probe into the central nervous condition, as evidenced in the two subjects who fell asleep with high xBRS and only 20% of relative variation.
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Affiliation(s)
| | - John M Karemaker
- Department of Medical Biology (Section Systems Physiology), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Emil Toader
- Department of Physiology, University of Lyon, Lyon, France
| | | | - Jos J Settels
- Edwards Lifesciences BMEYE, Amsterdam, The Netherlands
| | - Luc Quintin
- Department of Physiology, University of Lyon, Lyon, France
| | - Berend E Westerhof
- Department of Medical Biology (Section Systems Physiology), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands
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Stankovski T, Cooke WH, Rudas L, Stefanovska A, Eckberg DL. Time-frequency methods and voluntary ramped-frequency breathing: a powerful combination for exploration of human neurophysiological mechanisms. J Appl Physiol (1985) 2013; 115:1806-21. [PMID: 24114700 DOI: 10.1152/japplphysiol.00802.2013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We experimentally altered the timing of respiratory motoneuron activity as a means to modulate and better understand otherwise hidden human central neural and hemodynamic oscillatory mechanisms. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, tidal carbon dioxide concentrations, and muscle sympathetic nerve activity in 13 healthy supine young men who gradually increased or decreased their breathing frequencies between 0.05 and 0.25 Hz over 9-min periods. We analyzed results with traditional time- and frequency-domain methods, and also with time-frequency methods (wavelet transform, wavelet phase coherence, and directional coupling). We determined statistical significance and identified frequency boundaries by comparing measurements with randomly generated surrogates. Our results support several major conclusions. First, respiration causally modulates both sympathetic (weakly) and vagal motoneuron (strongly) oscillations over a wide frequency range-one that extends well below the frequency of actual breaths. Second, breathing frequency broadly modulates vagal baroreflex gain, with peak gains registered in the low frequency range. Third, breathing frequency does not influence median levels of sympathetic or vagal activity over time. Fourth, phase relations between arterial pressure and sympathetic and vagal motoneurons are unaffected by breathing, and are therefore likely secondary to intrinsic responsiveness of these motoneurons to other synaptic inputs. Finally, breathing frequency does not affect phase coherence between diastolic pressure and muscle sympathetic oscillations, but it augments phase coherence between systolic pressure and R-R interval oscillations over a limited portion of the usual breathing frequency range. These results refine understanding of autonomic oscillatory processes and those physiological mechanisms known as the human respiratory gate.
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