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Four kinds of infusions were made for 1 h periods into the 3rd cerebral ventricle of hydrated, conscious goats: 1) Angiotensin in hypertonic NaCI, 2) angiotensin in slightly hypotonic NaCI, 3) angiotensin in isotonic d‐glucose, and 4) hypertonic NaCI. The influence of these infusions on carotid blood pressure and fluid balance was studied. The infusions of angiotensin in hypertonic NaCl had conspicuous hypertensive, dipsogenic, antidiuretic and natriuretic effects. More moderate responses of the same kinds were obtained during the infusions of hypertonic NaCl and of angiotensin in slightly hypotonic NaCI. In contrast, no or only weak effects were obtained by the infusions of angiotensin in isotonic d‐glucose. The results are taken as support for the idea that a Na+ sensitive system in the vicinity of the 3rd ventricle may be of importance in the central contml of fluid balance and arterial blood pressure. Such a system may be influenced by the Na+ concentration of the cerebrospinal fluid, and angiotensin may either sensitize it to Na+ or make it more exposed to Na+ ions.

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Summary From 3 months of age until calving, repeated blood samplings were performed on 192 dairy heifers of three different breeds, Swedish Red and White Breed (SRB), Swedish Friesian Breed (SLB), Swedish Jersey Breed (SJB), and also reciprocal crosses between SRB and SLB. The heifers were reared on two different levels of feeding and kept tethered indoors all year round. The purpose was to obtain estimates of variation with age and to study influences of breed and level of feeding on blood composition. Samples were analysed for glucose and leukocytes in blood, as well as glucose, urea, creatinine, calcium (Ca), inorganic phosphorus (Pin) and magnesium (Mg) in plasma. All constituents were significantly affected by age (P < 0.001). The most obvious changes were observed in the mean creatinine concentration, which increased from approximately 80 μmol./l. at 3 and 6 months of age to 129 μmol./l. at 2 years, and in the mean level of Pin, which decreased from 2.8 mmol./l. to 2.2 mmol./l. For all constituents, apart from glucose, Pin and Mg in plasma, a highly significant effect of the individual animal was revealed. Repeatabilities were relatively high for creatinine and leukocytes (0.53 and 0.46, respectively), whereas they varied between 0.26 (blood glucose) and 0.07 (plasma glucose) for the other constituents. Breed effects were significant for all constituents, but only for creatinine were the differences marked. Animals on a high level of feeding had significantly higher levels of Pin in plasma (P < 0.001) but no differences were found for the other constituents (P > 0.05). The concentration of the constituents varied significantly (P < 0.001) between years and between seasons within years, but no consistent patterns could be observed. Correlations between the blood constituents were low. Zusammenfassung Leukozyten, Glukose, Harnstoff, Kreatinin, Kalzium, anorganischer Phosphor und Magnesium im Blut von Milchrindern im Alter von drei Monaten bis zur Abkalbung Bei 192 Milchrindern wurden ab einem Alter von 3 Monaten bis zur Abkalbung wiederholt Blutproben entnommen. Die Tiere gehörten zu folgenden Rassen: Swedish Red and White Breed (SRB), Swedish Friesian Breed (SLB), Swedish Jersey Breed (SJB) sowie reziproke Kreuzungen zwischen SRB und SLB. Die Färsen wurden in 2 Gruppen mit unterschiedlicher Fütterungsintensität aufgezogen, bei ganzjähriger Stallhaltung. Ziel der Untersuchungen war die Schätzung der altersabhängigen Variabilität und des Einflusses der Fütterungsintensität und Rasse auf folgende Blutbestandteile: Glukose, Leukocyten, Harnstoff, Kreatinin, Kalzium (Ca), anorganischer Phosphor (Pin) und Magnesium (Mg). Alle Kriterien waren signifikant vom Alter abhängig (P < 0,001). Die auffälligsten Veränderungen betrafen die durchschnittlichen Kreatininkonzentrationen, welche anstiegen von etwa 80 μmol/l im Alter von 3 bis 6 Monaten auf 129 ü/mol/l im Alter von 2 Jahren, sowie die Mittelwerte des Pin, die von 2,8 mmol/l auf 2,2 mmol/l abnahmen. Mit Ausnahme von Glukose, Pin und Mg im Plasma bestand für alle Pa...