1989 Fiscal Year Final Research Report Summary
Autonomic defense responses to extremely strong heat stress
| Project/Area Number |
61440027
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
環境生理学(含体力医学･栄養生理学)
|
|---|
| Research Institution | Kanazawa University |
|---|
Principal Investigator |
NAGASAKA Tetsuo Kanazawa University, School of Medicine, Professor, 医学部, 教授 (80023646)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HIRATA Kozo Kobe Women's College, Department of Home Economics, Associate Professor, 家政学部, 助教授 (70110624)
HIRAI Atsuo Kanazawa Women's Junior College, Associate Professor, 助教授 (00141367)
TANABE Minoru Kanazawa University, School of Medicine, Instructor, 医学部, 助手 (20217110)
SAKURADA Sotaro Kanazawa University, School of Medicine, Instructor, 医学部, 助手 (00215691)
SHIDO Osamu Kanazawa University, School of Medicine, Assistant Professor, 医学部, 講師 (40175386)
|
|---|
| Project Period (FY) |
1986 – 1989
|
| Keywords | Heat-induced Vasoconstriction / Arteriovenous Anastomoses / Skin Sympathetic Nerve Activity / Hyperthermia / Selective Brain Cooling / Emissary Veins |
|---|
| Research Abstract |
We studied thermoregulatory defense responses to extreme heat stress in human subjects. 1. Heat-induced skin vasoconstriction (HIVC). Finger vessels constricted and finger volume decreased when the hand was heated locally to temperature above body core temperature. This vasoconstriction was consistent when the subject was hyperthermic, and was not observed in the forearm skin where arteriovenous anastomoses (AVA) do not exist. HIVC was marked when the subject reported a sharp rise of local thermal sensation. During this period, skin sympathetic nerve activity to the hand increased. Partitional measurements of blood flow through superficial capillaries and deeply located AVA's confirmed that the vascular compartments responsible for HIVC were mainly AVA'S. From these results, we propose that HIVC is a response to retard heat transfer from hot contact objects to the body in already hyperthermic subjects. 2. Selective brain cooling enhanced by inward venous flowing through emissary veins. We confirmed that selective brain cooling via emissary veins such as angular oculi veins (AOV) was an important process enabling brain temperature (indicated by tympanic membrane temperature (T_<ty>)), to become lower than body core temperature in hyperthermic subjects. Mechanical obstruction of flow through AOV resulted an increase in the rise of T_<ty> during whole body warming. Mechanical obstruction of facial veins increased inward flowing of AOV-flow and suppressed the rate of rise in T_<ty>. These results strongly support the idea that emissary veins supply venous blood into the cavernous sinuses which act as a heat sink to cool the brain during hyperthermia in humans.
|
Research Products
(8 results)
