title: A near infrared spectroscopy study investigating oxygen utilisation in hydrocephalic rats.
abstract: Determination of hydrocephalus and its severity is important for optimal management of the condition. We have used near infrared spectroscopy (NIRS) to assess changes in concentrations of oxygenated (O2Hb), deoxygenated (HHb), total haemoglobin (tHb) and cytochrome c oxidase (Caa3) in normal and hydrocephalic Texas (HTx) rats in response to a 5 min head down tilt and a sodium pentobarbitone (NaPB) challenge. The former was used to test vascular responses and the latter to test metabolic responses. The haemoglobin oxygenation index (HbD) was derived which provides information regarding oxygen utilisation ([HbD]=[O2Hb]-[HHb]). With the tilt challenge, a significant (P=0.001) difference was observed in [HbD] between normal (n=24) and hydrocephalic (n=14) rats (-3.50 (-6.00 to 0.00) microM cm(-1 )and 7.50 (0.75 to 14.25) microM cm(-1), respectively). In another experiment we tested the response of ten rats to NaPB administration and observed a significant difference (P=0.008) in [Caa3] between normal (n=5) and hydrocephalic (n=5) rats (-6.60 (-7.55 to -5.50) microM cm(-1 )and -2.20 (-5.60 to -1.05) microM cm(-1), respectively). Coronal sections of these ten rat brains were analysed and significant (P<0.05) relationships were found between some of the NIRS parameters and cortical thickness or lateral ventricle area measurements. Our studies demonstrate that a significant difference in cerebral oxygenation and haemodynamics can be observed between normal and hydrocephalic HTx rats using NIRS.
authors.affiliation: School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M60 1QD, UK. zareen.bashir@postgrad.manchester.ac.uk
authors.forename: Zareen
authors.initials: Z
authors.lastname: Bashir
authors.forename: Jemma
authors.initials: J
authors.lastname: Miller
authors.forename: Jaleel Ahmad
authors.initials: JA
authors.lastname: Miyan
authors.forename: Maureen Susan
authors.initials: MS
authors.lastname: Thorniley
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000473:pathology; D004195:Disease Models, Animal; D018475:Head-Down Tilt; D006454:Hemoglobins / Q000378:metabolism; D006849:Hydrocephalus / Q000473:pathology / Q000503:physiopathology*; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D020547:Lateral Ventricles / Q000473:pathology; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D010424:Pentobarbital / Q000494:pharmacology; D051381:Rats; D011922:Rats, Mutant Strains; D012119:Respiration / Q000187:drug effects; D019265:Spectroscopy, Near-Infrared; D018709:Statistics, Nonparametric
chemical_list: D006454:Hemoglobins; D006993:Hypnotics and Sedatives; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010424:Pentobarbital