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4. Heat‐related changes in the velocity and kinetic energy of flowing blood influence the human heart's output during hyperthermia.

Author

Watanabe, Kazuhito, Koch Esteves, Nuno, Gibson, Oliver R., Akiyama, Koichi, Watanabe, Sumie, and González‐Alonso, José

Subjects
*FEVER, *BLOOD flow, *CARDIAC output, *PERIPHERAL circulation, *KINETIC energy
Abstract

Passive whole‐body hyperthermia increases limb blood flow and cardiac output (Q̇$\dot Q$), but the interplay between peripheral and central thermo‐haemodynamic mechanisms remains unclear. Here we tested the hypothesis that local hyperthermia‐induced alterations in peripheral blood flow and blood kinetic energy modulate flow to the heart and Q̇$\dot Q$. Body temperatures, regional (leg, arm, head) and systemic haemodynamics, and left ventricular (LV) volumes and functions were assessed in eight healthy males during: (1) 3 h control (normothermic condition); (2) 3 h of single‐leg heating; (3) 3 h of two‐leg heating; and (4) 2.5 h of whole‐body heating. Leg, forearm, and extracranial blood flow increased in close association with local rises in temperature while brain perfusion remained unchanged. Increases in blood velocity with small to no changes in the conduit artery diameter underpinned the augmented limb and extracranial perfusion. In all heating conditions, Q̇$\dot Q$ increased in association with proportional elevations in systemic vascular conductance, related to enhanced blood flow, blood velocity, vascular conductance and kinetic energy in the limbs and head (all R2 ≥ 0.803; P < 0.001), but not in the brain. LV systolic (end‐systolic elastance and twist) and diastolic functional profiles (untwisting rate), pulmonary ventilation and systemic aerobic metabolism were only altered in whole‐body heating. These findings substantiate the idea that local hyperthermia‐induced selective alterations in peripheral blood flow modulate the magnitude of flow to the heart and Q̇$\dot Q$ through changes in blood velocity and kinetic energy. Localised heat‐activated events in the peripheral circulation therefore affect the human heart's output. Key points: Local and whole‐body hyperthermia increases limb and systemic perfusion, but the underlying peripheral and central heat‐sensitive mechanisms are not fully established.Here we investigated the regional (leg, arm and head) and systemic haemodynamics (cardiac output: Q̇$\dot Q$) during passive single‐leg, two‐leg and whole‐body hyperthermia to determine the contribution of peripheral and central thermosensitive factors in the control of human circulation.Single‐leg, two‐leg, and whole‐body hyperthermia induced graded increases in leg blood flow and Q̇$\dot Q$. Brain blood flow, however, remained unchanged in all conditions. Ventilation, extracranial blood flow and cardiac systolic and diastolic functions only increased during whole‐body hyperthermia.The augmented Q̇$\dot Q$ with hyperthermia was tightly related to increased limb and head blood velocity, flow and kinetic energy.The findings indicate that local thermosensitive mechanisms modulate regional blood velocity, flow and kinetic energy, thereby controlling the magnitude of flow to the heart and thus the coupling of peripheral and central circulation during hyperthermia. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Dehydration reduces stroke volume and cardiac output during exercise because of impaired cardiac filling and venous return, not left ventricular function

Author

Watanabe, Kazuhito, Stohr, EricJ., Akiyama, Koichi, Watanabe, Sumie, Gonzalez-Alonso, Jose, Watanabe, Kazuhito, Stohr, EricJ., Akiyama, Koichi, Watanabe, Sumie, and Gonzalez-Alonso, Jose

Abstract

Dehydration accrued during intense prolonged whole-body exercise in the heat compromises peripheral blood flow and cardiac output ((Q) over dot). A markedly reduced stroke volume (SV) is a key feature of the dehydration-induced cardiovascular strain, but whether the lower output of the heart is mediated by peripheral or cardiac factors remains unknown. Therefore, we repeatedly quantified left ventricular (LV) volumes, LV mechanics (LV twist, a marker of systolic muscle function, and LV untwisting rate, an independent marker of LV muscle relaxation), left intra-ventricular pressure gradients, blood volume and peripheral blood flow during 2 hr of cycling in the heat with and without dehydration (DEH: 4.0 +/- 0.2% body mass loss and EUH: euhydration control, respectively) in eight participants (three females and five males). While brachial and carotid blood flow, blood volume, SV, LV end-diastolic volume (LVEDV), cardiac filling time, systemic vascular conductance and (Q) over dot were reduced in DEH compared to EUH after 2 hr, LV twist and untwisting rate tended to be higher (p = .09 and .06, respectively) and intra-ventricular pressure gradients were not different between the two conditions (p = .22). Furthermore, LVEDV in DEH correlated strongly with blood volume (r = .995, p < .01), head and forearms beat volume (r = .98, p < .05), and diastolic LV filling time (r = .98, p < .05). These findings suggest that the decline in SV underpinning the blunted (Q) over dot with exercise-induced dehydration is caused by compromised LV filling and venous return, but not intrinsic systolic or diastolic LV function.

Published
2023

18. Δ9-Tetrahydrocannabinol stimulation of estrogen receptor-positive MCF-7 breast cancer cell migration: Interfering interaction with the estrogenic milieu.

Author

Takeda, Shuso, Hirao-Suzuki, Masayo, Aramaki, Hironori, and Watanabe, Kazuhito

Abstract

Purpose: The effects of extended Δ9-tetrahydrocannabinol (Δ9-THC) exposure on estrogen receptor-positive human breast cancer MCF-7 cells have been investigated; however, the effects of Δ9-THC exposure for a shorter duration remain unclear. In this study, we sought to study whether Δ9-THC stimulates the migration of MCF-7 cells under both estrogenic and estrogen-deprived conditions over a short period (approximately 6 h). Methods: MCF-7 cells were treated with Δ9-THC under estrogenic or estrogen-deprived conditions, and cell migration was subsequently analyzed. Results: Δ9-THC-stimulated migration of MCF-7 cells 6 h after exposure was only observed in the estrogen-deprived condition. However, Δ9-THC-mediated migration was counteracted under estrogenic conditions without affecting cell proliferation and estrogen receptor expression during this period. Conclusions: Δ9-THC can stimulate MCF-7 cell migration under estrogen-deprived conditions; however, there is an interfering interaction between Δ9-THC and the estrogenic milieu that influences the migration of MCF-7 cells. [ABSTRACT FROM AUTHOR]

Published
2023
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40. Overview of Cannabis including Kampo Medicine and Therapy for Treatment of Dementia: A Review.

Author

Tibor, Wenger, Watanabe, Kazuhito, Sasaki, Yui, Kanazawa, Keiko, Shimizu, Koichi, Sirikantaramas, Supaart, Shoyama, Yoshinari, Taura, Futoshi, Morimoto, Satoshi, and Shoyama, Yukihiro

Subjects
JAPANESE herbal medicine, CANNABIS (Genus), CANNABIDIOL, PLANT fibers, CULTIVATED plants, CANNABINOIDS, ALZHEIMER'S patients
Abstract

Cannabis sativa L. is an annual herb oldest cultivated plants as a source of fiber since about 5000 B.C. On the other hand, the cannabis flower and seed are listed in Shennong's classic Materia Medica approximately 2000 years ago. The formulas prescribed with cannabis in Kampo medicine have been summarized. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are the major neurological and psychiatric cannabinoids, and develop to drugs. It becomes evident that the therapeutic CBD and/or THC are the important candidate of anti-dementia drugs having different mechanism for Alzheimer's patients. Two receptors and endocannabinoids are also discussed for underlying mechanism of action. In order to promote the breeding of cannabis plant containing higher concentration of target cannabinoid the biosynthetic enzymes were isolated, cloning and the tertiary structure of THCA synthase determined by x-ray analysis resulting in the possibility of molecular breeding for cannabinoids. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Ten years' experience in Niigata Prefecture Liver Disease Consultation Center

Author

Kamimura, Hiroteru, primary, Setsu, Toru, additional, Arao, Yoshihisa, additional, Hirokawa, Hikaru, additional, Sawaguri, Hiromi, additional, Watanabe, Fumiko, additional, Komoro, Yuko, additional, Sakamaki, Akira, additional, Tsuchiya, Atsunori, additional, Takamura, Masaaki, additional, Ikarashi, Masato, additional, Aoyagi, Yutaka, additional, Kikuta, Rei, additional, Watanabe, Kazuhito, additional, Nakayama, Hitoshi, additional, Tamura, Tsutomu, additional, and Terai, Shuji, additional

Published
2020
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