{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,28]],"date-time":"2025-09-28T04:12:47Z","timestamp":1759032767990},"reference-count":0,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[1973,9,1]],"date-time":"1973-09-01T00:00:00Z","timestamp":115689600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[1973,9]]},"abstract":"<jats:p>1. Mechanisms underlying the ability of ruminants to tolerate severe hypoglycaemia have been investigated. Anaesthetized sheep and rabbits were compared with respect to cerebral glucose transport and oxygen consumption as a function of glucose concentration in cerebral extracellular fluids.<\/jats:p><jats:p>2. Glucose in plasma was decreased by insulin or increased by \n<jats:sc>I.V.<\/jats:sc> infusion. Measurements were made of cerebral blood flow, arteriovenous concentration differences of glucose and oxygen and the concentration of glucose in c.s.f.<\/jats:p><jats:p>3. Equations for carrier\u2010mediated transport accurately described steady\u2010state glucose flux across the blood\u2014brain barrier as plasma concentration was varied from 0\u00b72 to 30 m\n<jats:sc>M<\/jats:sc>. In sheep, the affinity constant (<jats:italic>K<jats:sub>m<\/jats:sub><\/jats:italic>) was 6 m\n<jats:sc>M<\/jats:sc> and the maximum transport capacity (<jats:italic>\u1e6a<\/jats:italic><jats:sub>m<\/jats:sub>) was 260 \u03bcmole min<jats:sup>\u22121<\/jats:sup>. 100 g<jats:sup>1<\/jats:sup> brain. In rabbits, <jats:italic>K<jats:sub>m<\/jats:sub><\/jats:italic> = 5\u00b75 m\n<jats:sc>M<\/jats:sc> and <jats:italic>\u1e6a<\/jats:italic><jats:sub>m<\/jats:sub> = 280 \u03bcmole min<jats:sup>\u22121<\/jats:sup>. 100 g<jats:sup>1<\/jats:sup>. Transport of glucose across the blood\u2014brain barrier of rabbits is at least as efficient as that in sheep and in both species <jats:italic>\u1e6a<\/jats:italic><jats:sub>m<\/jats:sub> is 10\u201315 times greater than normal rates of glucose utilization.<\/jats:p><jats:p>4. During hypoglycaemia the concentration of glucose in c.s.f. is less in sheep than in rabbits (Fig. 5). Steady\u2010state utilization of glucose by sheep brain decreased to 50% of normal when steady\u2010state concentration of glucose in c.s.f. (interstitial fluid) falls to 0\u00b71 \u03bcmole ml.<jats:sup>\u22121<\/jats:sup>; in rabbits the corresponding concentration is 0\u00b77 \u03bcmole ml.<jats:sup>\u22121<\/jats:sup> (Fig. 6). We suggest that transport capacity of membranes separating cerebral interstitial fluid from the site of glucose phosphorylation is greater in sheep than in rabbits; this may be the principal adaptation which enables ruminants to withstand severe hypoglycaemia (Discussion II).<\/jats:p><jats:p>5. Approximately 30 min were required to reach a steady state of glucose transport following a sudden increment of glucose concentration in plasma (Fig. 1). 80\u2013100 min were required to reach a new steady\u2010state concentration of glucose in c.s.f.<\/jats:p><jats:p>6. The molar ratio of steady\u2010state cerebral glucose utilization to oxygen consumption (6<jats:italic>\u0120<\/jats:italic>:<jats:italic>\u022e<\/jats:italic><jats:sub>2<\/jats:sub>) is normally 0\u00b793 (\n<jats:sc>S.E.<\/jats:sc> \u00b1 0\u00b705) but is decreased to the range 0\u00b71\u20130\u00b75 during sustained hypoglycaemia in both sheep and rabbits (Figs. 2, 3). Continued low glucose: oxygen ratios could be explained by (<jats:italic>a<\/jats:italic>) utilization of non\u2010carbohydrate substrates derived from blood or (<jats:italic>b<\/jats:italic>) utilization of stored lipid in brain. Only 0\u00b71 g lipid\/100 g brain would suffice to account for the observed rate of non\u2010glucose oxidative metabolism during 3 hr of severe hypoglycaemia (Discussion IV).<\/jats:p>","DOI":"10.1113\/jphysiol.1973.sp010322","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T10:25:30Z","timestamp":1418984730000},"page":"529-551","source":"Crossref","is-referenced-by-count":98,"title":["Cerebral glucose transport and oxygen consumption in sheep and rabbits"],"prefix":"10.1113","volume":"233","author":[{"given":"J. R.","family":"Pappenheimer","sequence":"first","affiliation":[]},{"given":"B. P.","family":"Setchell","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[1973,9]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1973.sp010322","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1973.sp010322","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,8]],"date-time":"2023-11-08T20:40:19Z","timestamp":1699476019000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1973.sp010322"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1973,9]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1973,9]]}},"alternative-id":["10.1113\/jphysiol.1973.sp010322"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1973.sp010322","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1973,9]]}}}