Blood sampling from the retro-orbital plexus, the saphenous vein and the tail vein in rats: comparative effects on selected behavioural and blood variables

We compared the behaviours of rats, and measured various blood parameters, after three blood sampling techniques: orbital puncture while they were under diethyl-ether anaesthesia, blood collection by tail vein puncture under O2-N 2O-halothane anaesthesia and puncture of the saphenous vein without anaesthesia. Twelve rats were subjected to the three treatments according to a Latin square design. After each treatment, the behaviour of the rats was automatically monitored using the so-called LABORASTM method, which discriminates between grooming, locomotion and inactivity in rats. Based on excitation scores and urine production, it was found that induction of diethyl-ether anaesthesia combined with orbital puncture caused more distress than did the other two blood sampling techniques. The three techniques had no differential effects on the behaviours of grooming, locomotion and inactivity. Collecting 0.5 ml of blood by orbital puncture was ± 7 times faster than doing so by saphenous vein puncture and ± 15 times faster than collecting blood by tail vein puncture while the rats were under O2-N 2O-halothane anaesthesia. The levels of some haematological and plasma variables differed significantly between the three blood collection techniques. These observations may help to select the most appropriate technique of blood sampling with respect to anticipated discomfort in the animals.

Histological changes in the orbital region of rats after orbital puncture

To contribute to the assessment of the degree of discomfort in rats after orbital puncture, we have examined the histological changes in the intra-orbital tissues caused by this technique of blood sampling. Orbits were studied from rats euthanized either within 1 min, 4 days, 28 days or 56 days after puncture while under diethyl-ether anaesthesia. The techniques of 2 animal technicians were compared, one using a broken haematocrit capillary and the other using an intact Pasteur's pipette. Non-punctured orbits served as controls. Microscopic slides containing the eye in situ at 2 horizontal levels in the orbital region were examined for 37 parameters; the slides were scored blind and in random order. Orbital puncture caused haemorrhages in the puncture track and, depending on the technique used, also in the periosteum. Four days after puncture, inflammatory reactions were present in the puncture track. Depending on the technique of puncture, these reactions were also seen in the eye muscles and periosteum or in the Harderian gland. Within 4 weeks after puncture, the lesions had healed without detectable scars. The different histological effects of the 2 techniques of orbital puncture are discussed in the light of the characteristics of these techniques.

Protein synthesis in rat tissues during lactation. No effect of diethyl ether anaesthesia

Rates of protein synthesis were measured in mammary gland, liver, intestinal mucosa and muscle of lactating rats by using a flooding dose of [3H]phenylalanine that was injected into diethyl ether-anaesthetized dams via a lateral vein or into undisturbed dams via a jugular cannula. Ether anaesthesia did not alter rates of protein synthesis significantly in any tissue.

INSULIN AND GLUCOSE LEVELS IN ACUTE AND CHRONICALLY URAEMIC RATS

Departments of Physiology and Pathology, Faculty of Medicine, University of Khartoum, P.O. Box 102, Khartoum, Sudan (Received 31 October 1977) The important role of the kidney in the degradation and excretion of insulin has recently been reviewed (Rubenstein & Spitz, 1968; Rubenstein, Mako & Horwitz, 1975). The kidney functions with a wide margin of safety but the minimum functional renal mass required for the effective elimination of insulin is not known. The present report deals with the effects of total and five-sixths nephrectomy on the concentrations of insulin and glucose in the blood. The effects of uraemia itself, produced by bilateral ureteric ligation, have also been studied. Albino rats of the Wistar strain (mean weight 232 ± 5 (s.e.m.) g) were used. Except for ten female rats included in the acutely uraemic group, the remainder of the animals were male. The subsequent operations were performed under open diethyl ether anaesthesia