caa a22 4500 469055049 CHVBK 20180323132841.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF00376447 doi (NATIONALLICENCE)springer-10.1007/BF00376447 Blood flow through the ophthalmic veins during exercise in humans [Elektronische Daten] [Masami Hirashita, Osamu Shido, Minoru Tanabe] Summary: The blood from the face flows into the intracranium through the ophthalmic veins when human subjects become hyperthermic. To investigate a possible mechanism underlying this change in direction of flow, five young men were subjected to either passive body warming or exercise on a cycle ergometer, in a climatic chamber whose air temperature and relative humidity were 28°C and 40%. Tympanic (T ty) and oesophageal temperatures, forehead sweat rate (m sw), skin blood flow. (Q sk) and blood flow through the ophthalmic vein (Q ov) were measured, and the mean skin (T sk) and mean body (T b) temperatures were computed. Passive body warming was induced by a box-shaped body warming unit enclosing all but the subject's head. Exercise was performed either at an intensity of 60% maximal oxygen consumption or with the intensity increasing in increments. During both tests, m sw and Q sk started to increase shortly after the imposition of the heat load. The Q ov began to change with the venous blood flowing from the face into the intracranium and a complete reversal in the direction of Q ov (from the face to the intracranium). came significantly later than the increases in Q sw and Q sk. The T ty at the time of flow reversal was the same in both tests. The T sk (and hence T b) at flow reversal was, however, significantly higher during passive body warming than during exercise. The mechanism for switching the direction of Q ov appeared to have been triggered by a high temperature in the brain, and not by thermal input from the periphery of the body. In a febrile subject who volunteered for this study, the direction of Q ov was consistently inwards even when sitting quietly. From these results, we suggest that there are elements within the brain that control the mechanisms for switching the direction of venous flow through the emissary veins to keep the brain cool during hyperthermia. Springer-Verlag, 1992 Passive body warming nationallicence Cycle exercise nationallicence Emissary veins nationallicence Flow reversal nationallicence Tympanic temperature nationallicence Oesophageal temperature nationallicence Hirashita Masami Kanazawa College of Economics, 920, Gosho-machi, Kanazawa, Japan aut Shido Osamu Department of Physiology, School of Medicine, Kanazawa University, 920, Takara-machi, Kanazawa, Japan aut Tanabe Minoru Department of Physiology, School of Medicine, Kanazawa University, 920, Takara-machi, Kanazawa, Japan aut European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 64/1(1992-01-01), 92-97 0301-5548 64:1<92 1992 64 421 https://doi.org/10.1007/BF00376447 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00376447 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hirashita Masami Kanazawa College of Economics, 920, Gosho-machi, Kanazawa, Japan aut NATIONALLICENCE 700 1- Shido Osamu Department of Physiology, School of Medicine, Kanazawa University, 920, Takara-machi, Kanazawa, Japan aut NATIONALLICENCE 700 1- Tanabe Minoru Department of Physiology, School of Medicine, Kanazawa University, 920, Takara-machi, Kanazawa, Japan aut NATIONALLICENCE 773 0- European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 64/1(1992-01-01), 92-97 0301-5548 64:1<92 1992 64 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer